Multi-pass hot-rolling technique was used to fabricate W80Cu20 alloy,and its properties were characterized in this paper.Results show that the W-Cu alloy sheets with a thickness of 0.5 mm and a relative density of99.8...Multi-pass hot-rolling technique was used to fabricate W80Cu20 alloy,and its properties were characterized in this paper.Results show that the W-Cu alloy sheets with a thickness of 0.5 mm and a relative density of99.87%can be successfully made using this new technique at 800℃.In hot-rolling process,Cu phases are closely surrounded by W particles under the rolling stress to form a network microstructure,thus making significant increase in electrical and thermal conductivity up to53.00%and 24.44%,respectively.Transverse and longitudinal hardness of the W–Cu sheets significantly increase due to the enhanced densification and deformation strength.Similar to that of the raw materials,three fracture types were observed in the hot-rolled materials,i.e.,ductile fracture of Cu binding phases,trans-granular fracture of W phases,and W–W interfacial fracture.展开更多
Numerical simulation on microstructural evolution during multipass hot rolling of aluminum alloys was performed by using DEFORM TM software and incorporating Zener Hollomon parameter Z . The distributions of equivalen...Numerical simulation on microstructural evolution during multipass hot rolling of aluminum alloys was performed by using DEFORM TM software and incorporating Zener Hollomon parameter Z . The distributions of equivalent stress, equivalent strain, equivalent strain rate and temperature, as well as the distribution of recrystallization fraction through the thickness of deformed specimen during multipass hot rolling of 5182 aluminum alloy, were all calculated. The results agree well with the metallographic examination of the deformed specimen on Gleeble 1500. [展开更多
Taking the seamless tube plant of Baoshan Iron & Steel Complex in China as the background,we analyze the characters of hot rolling seamless steel tube:multi varieties,low volume,complicated production process,flex...Taking the seamless tube plant of Baoshan Iron & Steel Complex in China as the background,we analyze the characters of hot rolling seamless steel tube:multi varieties,low volume,complicated production process,flexible production routes.Then integrated scheduling problem for hot rolling seamless steel tube production is studied,which covers two key points;order-grouping problem and solution method for flowshop/jobshop scheduling problem.On the basis of these two problems,integrated scheduling decision system is developed.The design idea,function flow sheet,data processing method,and functional module of visualized human-computer interactive scheduling system implemented in seamless steel tube plant of Shanghai Baoshan Iron & Steel Complex are described into detail.Compared with manual system,the performance of system shows the applicability and superiority in several criteria.展开更多
To establish the rolling plan of cold-rolling flattening set is very complicated,it is restrained by several constraints of rolling schedule.Operator's subjective and other human factors also affect the rationalit...To establish the rolling plan of cold-rolling flattening set is very complicated,it is restrained by several constraints of rolling schedule.Operator's subjective and other human factors also affect the rationality of plan arrangement seriously.Its result causes many abuses such as overusing transition strip,high-frequent roller switching,no-fully utilization of rollers,low arrangement rate of the plan.Therefore,we have initially developed a practical optimization model of rolling plan and schedule,which could be established and optimized by computer automatically,and a dynamic alignment module which have friendly UI according to the experience of operators.They have greatly enhanced the system usability.This system takes full advantage of relationship between the roller roughness and the rolling weight,reasonably arranges rolling based on different roughness demand,effectively enhances the use factor of roller and the smooth quality of steel string coil. A practical and effective scheduling optimization algorithm and rolling scheduling optimization applications system was developed based on the study of mixed hot rolling scheduling optimization model of carbon steel,stainless steel,stainless steel and carbon steel cross-rolling.The online application indicates that the model and algorithm is designed reasonable,practical and effective.This model system can significantly improve the scheduling efficiency and quality and it's also very positive in reducing heating energy consumption,enhancing the volume of units rolling plan,and optimizing the production of hot-rolled unit organization and planning and scheduling.展开更多
This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir welding.The results showed that ultimate tensile...This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir welding.The results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum,and the tensile specimens fractured at the matrix after exceeding 1 Pa.Non-equilibrium grain boundaries were formed at the hot-rolled interface,and a large amount of Mg_(2)Si particles were linearly precipitated along the interfacial grain boundaries(IGBs).During subsequent heat treatment,Mg_(2)Si particles dissolved back into the matrix,and Al_(2)O_(3) film remaining at the interface eventually evolved into MgO.In addition,the local IGBs underwent staged elimination during HRB,which facilitated the interface healing due to the fusion of grains at the interface.This process was achieved by the dissociation,emission,and annihilation of dislocations on the IGBs.展开更多
Higher requirements for the accuracy of relevant models are put throughout the transformation and upgrade of the iron and steel sector to intelligent production.It has been difficult to meet the needs of the field wit...Higher requirements for the accuracy of relevant models are put throughout the transformation and upgrade of the iron and steel sector to intelligent production.It has been difficult to meet the needs of the field with the usual prediction model of mechanical properties of hotrolled strip.Insufficient data and difficult parameter adjustment limit deep learning models based on multi-layer networks in practical applications;besides,the limited discrete process parameters used make it impossible to effectively depict the actual strip processing process.In order to solve these problems,this research proposed a new sampling approach for mechanical characteristics input data of hot-rolled strip based on the multi-grained cascade forest(gcForest)framework.According to the characteristics of complex process flow and abnormal sensitivity of process path and parameters to product quality in the hot-rolled strip production,a three-dimensional continuous time series process data sampling method based on time-temperature-deformation was designed.The basic information of strip steel(chemical composition and typical process parameters)is fused with the local process information collected by multi-grained scanning,so that the next link’s input has both local and global features.Furthermore,in the multi-grained scanning structure,a sub sampling scheme with a variable window was designed,so that input data with different dimensions can get output characteristics of the same dimension after passing through the multi-grained scanning structure,allowing the cascade forest structure to be trained normally.Finally,actual production data of three steel grades was used to conduct the experimental evaluation.The results revealed that the gcForest-based mechanical property prediction model outperforms the competition in terms of comprehensive performance,ease of parameter adjustment,and ability to sustain high prediction accuracy with fewer samples.展开更多
A new type of hot-rolled transformation induced plasticity (TRIP) steel with 2.3%AI was developed to replace conventional Si-bearing TRIP steel to improve surface quality of the steel sheet. The relationship between...A new type of hot-rolled transformation induced plasticity (TRIP) steel with 2.3%AI was developed to replace conventional Si-bearing TRIP steel to improve surface quality of the steel sheet. The relationship between retained austenite volume fraction and hot-rolling processing was researched by Gleeble-2000 thermo-dynamic test for the Al-bearing steel. The experimental result showed that aluminum played an important role on retaining austenite and the volume fraction increased from 4.4% to 7.5% as coiling temperature increased from 350℃ to 450℃, while coiling temperature had a stronger effect on retaining austenite than finishing rolling temoerature.展开更多
The microstructure characteristics with super fine ferrite grain size less than 5mm, appropriate retained austenite fraction around 5.0% and or removable abundant dislocations have been obtained by controlled rolling ...The microstructure characteristics with super fine ferrite grain size less than 5mm, appropriate retained austenite fraction around 5.0% and or removable abundant dislocations have been obtained by controlled rolling and cooling, which leads to well balance com- prehensive properties with high tensile strength of 510 and 615MPa, high elongation of 40% and 27%, low ratio of yield strength to tensile strength 0.83 and 0.80, as well as low ductile- brittle transition temperature less than -80 and -70℃ for advanced aluminum hot-rolled TRIP steel and silicon hot-rolled TRIP steel, respectively.展开更多
The types and growth of various oxide scales formed during the different phases of the production of hotrolled strip steel products are reviewed. Similarities and differences between the "tertiary scale" on the surf...The types and growth of various oxide scales formed during the different phases of the production of hotrolled strip steel products are reviewed. Similarities and differences between the "tertiary scale" on the surface of carbon steels at high temperatures and the oxide scale on pure iron are compared. The micro-structural features of the "final oxide scale" on the surface of strip steels at room temperature as well as the relationship between these features and the position of the steel coil (plate) and the subsequent processes of recoiling, temper rolling and trimming, etc. are summarized. The actual oxide scales retained on the commercial hot-rolled strip steels at room temperature have been proposed to define as " quartus scale" for the first time. The micro-structural development and phase transformation of the initial "tertiary scale" during and after cooling and coiling are described. The reasons for the "tertiary scale" on carbon steels differing from the oxide scale formed on pure iron, and the major influencing factors in the formation of various types of "quartus scales" are analyzed from both thermodynamic and dynamic viewpoints. The development mechanism of " quartus scales" is discussed and the potential effects of the " quartus scale" state (thickness, constitution, structure and defects), on the rusting and pickling properties of commercial hot-rolled strip steel, as well as on the mechanical properties of oxide scales are analyzed.展开更多
In order to simplify production process and to decrease production cost of thicker cold-rolled iF steel sheets for deep drawing applications, a new hot-rolled IF steel sheet is developed through hot-rolling in or regi...In order to simplify production process and to decrease production cost of thicker cold-rolled iF steel sheets for deep drawing applications, a new hot-rolled IF steel sheet is developed through hot-rolling in or region. In this paper, properties, microstructures and precipitate morphology of hot-rolled iF steel sheets are described..展开更多
Wear-resistant cladding plates consisting of a substrate(Q345 R) and a clad layer(BTW1) were bonded through hot rolling at the temperature of 1 200 ℃ and a rolling speed of 0.5 m/s. The microhardness of the cladd...Wear-resistant cladding plates consisting of a substrate(Q345 R) and a clad layer(BTW1) were bonded through hot rolling at the temperature of 1 200 ℃ and a rolling speed of 0.5 m/s. The microhardness of the cladding plate was also tested after being heat treated. The microstructure evolution on the interface of BTW1/Q345 R sheets under various reduction rates was investigated with a scanning electron microscope(SEM) and EBSD. It is found that the micro-cracks and oxide films on the interface disappear when the reduction is 80%, whereas the maximum uniform diffusion distance reaches 10 μm. As a result, a wide range of metallurgical bonding layers forms, which indicates an improved combination between the BTW1 and the Q345 R. Additionally, it is discovered that the unbroken oxide films on the interface are composed of Mn, Si or Cr at the reductions of 50% and 65%. The SEM fractography of tensile specimen demonstrates that the BTW1 has significant dimple characteristics and possesses lower-sized dimples with the increment in reduction, suggesting that the toughness and bonding strength of the cladding plates would be improved by the increase of reduction. The results reveal that a high rolling reduction causes the interfacial oxide film broken and further forms a higher-sized composite metallurgical bonding interface. The peak microhardness is achieved near the interface.展开更多
Hot-rolled wide strip for production of large diameter,heavy gauged(up to 19 mm) helical line pipe grade X80 was a priority development over the last three years.Microstructure,texture and mechanical properties of str...Hot-rolled wide strip for production of large diameter,heavy gauged(up to 19 mm) helical line pipe grade X80 was a priority development over the last three years.Microstructure,texture and mechanical properties of strips have been characterised.Also the welding conditions have been simulated.The favourable microstructure is achieved by the proper selection of an appropriate chemical composition of low carbon content and increased niobium micro alloying in combination with suitable strictly controlled hot-rolling parameters.The addition of niobium in combination with the adjustment of other alloying elements increases the recrystallisation stop temperature and thus makes it possible to apply a high temperature processing(HTP) concept.The homogeneous bainitic microstructure across the strip gauge is then formed during accelerated cooling on the run-out table of the hot-rolling mill.All results indicated excellent properties of these hot strips which make it suitable for spiral pipes of grade X80 for example 18.9mm×Φ1 220 mm at dimension.展开更多
As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufact...As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufacturing, transportation and/or storage of the plates. General corrosion often takes place on the surface of a plate in the exterior part of a package, and only reduces the thickness of the plate and slightly increases the roughness of the surface; however, localized corrosion on the surface of a plate inside the package is likely to result in the formation of pit-like defects on the substrate of the plate, which cannot be removed thoroughly by normal acid pickling or sand blasting, and affects the application of the plate. This research report analyzes the phenomena and characteristics of the rusting behavior of hot- rolled steel plates for automobile applications, and the influencing factors are summaried. The corresponding preventative measures are proposed.展开更多
In order to master mechanical property, surface quality and microstructure of constraint cooling (CC) coils undervarious water cooling parameters, more than 100 coils cooling experiments were done with real production...In order to master mechanical property, surface quality and microstructure of constraint cooling (CC) coils undervarious water cooling parameters, more than 100 coils cooling experiments were done with real production process,of which is designed a cooling experimental instrument in the end. The experiments show that high initial coolingtemperature, discontinuous cooling style, and long cooling time can improve mechanical property of cooling coilsand shorten cooling time. The CC coils experiments cover the different steel grades, so that CC process effects onhot-rolled coils may be predicted and controlled actively.展开更多
Influence of thermo-mechanical controlled processing(TMCP),including two-stage rolling with laminar cooling,air cooling and ultra-fast cooling,on the microstructure and mechanical properties of three kinds of Nb-micro...Influence of thermo-mechanical controlled processing(TMCP),including two-stage rolling with laminar cooling,air cooling and ultra-fast cooling,on the microstructure and mechanical properties of three kinds of Nb-microalloeyed steels was investigated by hot-rolling experiment.Effect of chemistry compositions and microstructure on mechanical properties and the relationship between the multiphase microstructure' s formation with TMCP were analyzed.The results showed that the mixed microstructure containing ferrite,bainite,martensite and a small amount of retained austenite can be obtained by thermo-mechanical controlled processing.Size, quantity and distribution of the constituents(ferrite grain,bainite packet and M-A islands) significantly affect the mechanical properties of three kinds of Nb-microalloyed steels.Under the condition of similar TMCP parameters, there is a gradually decreasing tendency in tensile strength from high silicon Nb steel,high silicon Nb-Ti steel to low silicon Nb-Ti steel,and an opposite tendency in total elongation and product of tensile strength and ductility. Total elongation and product of tensile strength and ductility reach the maximum values(41%and 25256 MPa% respectively) for low silicon Nb-Ti steel.展开更多
In this study, the welding technology of the hot-rolled extra-high-strength steel, BS960QC, has been comprehensively investigated. Analysis has been made on the weldability ,the different welding procedures ,the mecha...In this study, the welding technology of the hot-rolled extra-high-strength steel, BS960QC, has been comprehensively investigated. Analysis has been made on the weldability ,the different welding procedures ,the mechanical properties, and the fatigue properties, and a set of recommendation guidelines have been proposed for evaluating the welded joints of the extra-high-strength steel. The research and results indicate that the hot-rolled extra-high-strength steel, BS960QC,has good weldability and an excellent adaptability to welding procedures. Further,the excellent mechanical properties and fatigue properties of the welded joints ,which can be achieved by using optimized welding procedures, can completely meet the technical requirements of the construction machinery industry.展开更多
The patenting process of three hot-rolled steels with carbon mass contents of 0.70%-0. 90% was studied. The effect of the quenching temperature on the cementite lamellar distance in the steel was evaluated on the basi...The patenting process of three hot-rolled steels with carbon mass contents of 0.70%-0. 90% was studied. The effect of the quenching temperature on the cementite lamellar distance in the steel was evaluated on the basis of microstructural characterization and mechanical property tests. The patenting treatment of high-carbon hot- rolled strip and its application in springs were discussed.展开更多
Results presented in this study contribute to investigation of the microstructure and mechanical properties of the hot-rolled Fe16Mn0.6C steel plates.The steel plates have been produced by being hot-rolled at temperat...Results presented in this study contribute to investigation of the microstructure and mechanical properties of the hot-rolled Fe16Mn0.6C steel plates.The steel plates have been produced by being hot-rolled at temperatures ranging from 1100℃ to 850℃ in seven passes to 97.5% reduction in thickness and then cooled in a furnace of 650℃.Some plates have been annealed at temperatures ranging from 300℃ to 1100℃ for 5min to 60min,and then followed by water quenching.There are annealing twins in the hot-rolled Fe16Mn0.6C steel.Fe16Mn0.6C steel presents similar ductile behavior as X-IPTM steel,but much higher elongation than commercial martensitic steel (MP) 1000,dual phase (DP) 980,and transformation induced plasticity (TRIP) 980 steels.Fe16Mn0.6C steel experiences γε (-α) transformation in some local regions,but remains mostly austenite during the entire deformation process.Fe16Mn0.6C steel with special mechanical properties can be produced by using the appropriate anneal technology.Twinning induced plasticity(TWIP) effect only occurs in the Fe16Mn0.6C steel annealed at temperature higher than 900℃.展开更多
The critical transformation temperatures,A_(c1) and A_(c3),of a hot-rolled low-carbon titanium microalloyed steel were determined as a part of an examination of its phase-transformation behavior. Austenite decompositi...The critical transformation temperatures,A_(c1) and A_(c3),of a hot-rolled low-carbon titanium microalloyed steel were determined as a part of an examination of its phase-transformation behavior. Austenite decomposition during the continuous cooling of the titanium microalloyed steel was studied by heating it to 1 250 ℃,cooling it to 880 ℃,holding for 2 s,and then cooling it to room temperature at different cooling rates. The transformation kinetics( CCT curve) was characterized as well.展开更多
In this study, the matrix structure, state and composition of the mill scales of four typical domestically made 510L hot-rolled strips were observed and analyzed by means of optical microscopy (OM) ,scanning electro...In this study, the matrix structure, state and composition of the mill scales of four typical domestically made 510L hot-rolled strips were observed and analyzed by means of optical microscopy (OM) ,scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion behavior of the steels with and without mill scales were investigated by means of hot-humid corrosion tests under the condition of relative humidity ( RH ) of 95% at 50℃ and 70℃, respectively. The results show that the matrix structures, state, composition and thickness of mill scales vary in the strips. The rusting starting time of the specimens with scales is generally a bit longer than that of the specimens without scales, but their corrosion mass-gain is higher. For these two kinds of specimens ,their corrosion rate increases significantly with the increase of temperature. The rusting behavior of the 510L strips produced by various plants is different due to the variations of hot-rolling processes and designed chemical compositions. Various relevant aspects should be taken into account in the evaluation of the corrosion behavior of hot-rolled strips.展开更多
基金supported by the National Natural Science Foundation of China (No. 50834003)
文摘Multi-pass hot-rolling technique was used to fabricate W80Cu20 alloy,and its properties were characterized in this paper.Results show that the W-Cu alloy sheets with a thickness of 0.5 mm and a relative density of99.87%can be successfully made using this new technique at 800℃.In hot-rolling process,Cu phases are closely surrounded by W particles under the rolling stress to form a network microstructure,thus making significant increase in electrical and thermal conductivity up to53.00%and 24.44%,respectively.Transverse and longitudinal hardness of the W–Cu sheets significantly increase due to the enhanced densification and deformation strength.Similar to that of the raw materials,three fracture types were observed in the hot-rolled materials,i.e.,ductile fracture of Cu binding phases,trans-granular fracture of W phases,and W–W interfacial fracture.
文摘Numerical simulation on microstructural evolution during multipass hot rolling of aluminum alloys was performed by using DEFORM TM software and incorporating Zener Hollomon parameter Z . The distributions of equivalent stress, equivalent strain, equivalent strain rate and temperature, as well as the distribution of recrystallization fraction through the thickness of deformed specimen during multipass hot rolling of 5182 aluminum alloy, were all calculated. The results agree well with the metallographic examination of the deformed specimen on Gleeble 1500. [
文摘Taking the seamless tube plant of Baoshan Iron & Steel Complex in China as the background,we analyze the characters of hot rolling seamless steel tube:multi varieties,low volume,complicated production process,flexible production routes.Then integrated scheduling problem for hot rolling seamless steel tube production is studied,which covers two key points;order-grouping problem and solution method for flowshop/jobshop scheduling problem.On the basis of these two problems,integrated scheduling decision system is developed.The design idea,function flow sheet,data processing method,and functional module of visualized human-computer interactive scheduling system implemented in seamless steel tube plant of Shanghai Baoshan Iron & Steel Complex are described into detail.Compared with manual system,the performance of system shows the applicability and superiority in several criteria.
文摘To establish the rolling plan of cold-rolling flattening set is very complicated,it is restrained by several constraints of rolling schedule.Operator's subjective and other human factors also affect the rationality of plan arrangement seriously.Its result causes many abuses such as overusing transition strip,high-frequent roller switching,no-fully utilization of rollers,low arrangement rate of the plan.Therefore,we have initially developed a practical optimization model of rolling plan and schedule,which could be established and optimized by computer automatically,and a dynamic alignment module which have friendly UI according to the experience of operators.They have greatly enhanced the system usability.This system takes full advantage of relationship between the roller roughness and the rolling weight,reasonably arranges rolling based on different roughness demand,effectively enhances the use factor of roller and the smooth quality of steel string coil. A practical and effective scheduling optimization algorithm and rolling scheduling optimization applications system was developed based on the study of mixed hot rolling scheduling optimization model of carbon steel,stainless steel,stainless steel and carbon steel cross-rolling.The online application indicates that the model and algorithm is designed reasonable,practical and effective.This model system can significantly improve the scheduling efficiency and quality and it's also very positive in reducing heating energy consumption,enhancing the volume of units rolling plan,and optimizing the production of hot-rolled unit organization and planning and scheduling.
基金This work was financially supported by the National Key Research and Development Program of China(No.2018YFA0707300)the Key Research and Development Program projects of Shandong(No.2020CXGC010304).
文摘This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hotroll bonding(HRB)based on friction stir welding.The results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum,and the tensile specimens fractured at the matrix after exceeding 1 Pa.Non-equilibrium grain boundaries were formed at the hot-rolled interface,and a large amount of Mg_(2)Si particles were linearly precipitated along the interfacial grain boundaries(IGBs).During subsequent heat treatment,Mg_(2)Si particles dissolved back into the matrix,and Al_(2)O_(3) film remaining at the interface eventually evolved into MgO.In addition,the local IGBs underwent staged elimination during HRB,which facilitated the interface healing due to the fusion of grains at the interface.This process was achieved by the dissociation,emission,and annihilation of dislocations on the IGBs.
基金financially supported by the National Natural Science Foundation of China(No.52004029)the Fundamental Research Funds for the Central Universities,China(No.FRF-TT-20-06).
文摘Higher requirements for the accuracy of relevant models are put throughout the transformation and upgrade of the iron and steel sector to intelligent production.It has been difficult to meet the needs of the field with the usual prediction model of mechanical properties of hotrolled strip.Insufficient data and difficult parameter adjustment limit deep learning models based on multi-layer networks in practical applications;besides,the limited discrete process parameters used make it impossible to effectively depict the actual strip processing process.In order to solve these problems,this research proposed a new sampling approach for mechanical characteristics input data of hot-rolled strip based on the multi-grained cascade forest(gcForest)framework.According to the characteristics of complex process flow and abnormal sensitivity of process path and parameters to product quality in the hot-rolled strip production,a three-dimensional continuous time series process data sampling method based on time-temperature-deformation was designed.The basic information of strip steel(chemical composition and typical process parameters)is fused with the local process information collected by multi-grained scanning,so that the next link’s input has both local and global features.Furthermore,in the multi-grained scanning structure,a sub sampling scheme with a variable window was designed,so that input data with different dimensions can get output characteristics of the same dimension after passing through the multi-grained scanning structure,allowing the cascade forest structure to be trained normally.Finally,actual production data of three steel grades was used to conduct the experimental evaluation.The results revealed that the gcForest-based mechanical property prediction model outperforms the competition in terms of comprehensive performance,ease of parameter adjustment,and ability to sustain high prediction accuracy with fewer samples.
文摘A new type of hot-rolled transformation induced plasticity (TRIP) steel with 2.3%AI was developed to replace conventional Si-bearing TRIP steel to improve surface quality of the steel sheet. The relationship between retained austenite volume fraction and hot-rolling processing was researched by Gleeble-2000 thermo-dynamic test for the Al-bearing steel. The experimental result showed that aluminum played an important role on retaining austenite and the volume fraction increased from 4.4% to 7.5% as coiling temperature increased from 350℃ to 450℃, while coiling temperature had a stronger effect on retaining austenite than finishing rolling temoerature.
文摘The microstructure characteristics with super fine ferrite grain size less than 5mm, appropriate retained austenite fraction around 5.0% and or removable abundant dislocations have been obtained by controlled rolling and cooling, which leads to well balance com- prehensive properties with high tensile strength of 510 and 615MPa, high elongation of 40% and 27%, low ratio of yield strength to tensile strength 0.83 and 0.80, as well as low ductile- brittle transition temperature less than -80 and -70℃ for advanced aluminum hot-rolled TRIP steel and silicon hot-rolled TRIP steel, respectively.
文摘The types and growth of various oxide scales formed during the different phases of the production of hotrolled strip steel products are reviewed. Similarities and differences between the "tertiary scale" on the surface of carbon steels at high temperatures and the oxide scale on pure iron are compared. The micro-structural features of the "final oxide scale" on the surface of strip steels at room temperature as well as the relationship between these features and the position of the steel coil (plate) and the subsequent processes of recoiling, temper rolling and trimming, etc. are summarized. The actual oxide scales retained on the commercial hot-rolled strip steels at room temperature have been proposed to define as " quartus scale" for the first time. The micro-structural development and phase transformation of the initial "tertiary scale" during and after cooling and coiling are described. The reasons for the "tertiary scale" on carbon steels differing from the oxide scale formed on pure iron, and the major influencing factors in the formation of various types of "quartus scales" are analyzed from both thermodynamic and dynamic viewpoints. The development mechanism of " quartus scales" is discussed and the potential effects of the " quartus scale" state (thickness, constitution, structure and defects), on the rusting and pickling properties of commercial hot-rolled strip steel, as well as on the mechanical properties of oxide scales are analyzed.
基金The auLhors thank for the financial aid from Scienceamend of Shandong Province (No. Q98F05146)
文摘In order to simplify production process and to decrease production cost of thicker cold-rolled iF steel sheets for deep drawing applications, a new hot-rolled IF steel sheet is developed through hot-rolling in or region. In this paper, properties, microstructures and precipitate morphology of hot-rolled iF steel sheets are described..
基金the National Natural Science Foundation of China(No.U151013)the Key Research and Development Program of Shanxi Province(Nos.201603D111004 and 201603D121010)+1 种基金the Natural Science Foundation of Shanxi Province of Chinathe Provincial Special Fund for Coordinative Innovation Center of Taiyuan Heavy Machinery Equipmen(No.20171003)
文摘Wear-resistant cladding plates consisting of a substrate(Q345 R) and a clad layer(BTW1) were bonded through hot rolling at the temperature of 1 200 ℃ and a rolling speed of 0.5 m/s. The microhardness of the cladding plate was also tested after being heat treated. The microstructure evolution on the interface of BTW1/Q345 R sheets under various reduction rates was investigated with a scanning electron microscope(SEM) and EBSD. It is found that the micro-cracks and oxide films on the interface disappear when the reduction is 80%, whereas the maximum uniform diffusion distance reaches 10 μm. As a result, a wide range of metallurgical bonding layers forms, which indicates an improved combination between the BTW1 and the Q345 R. Additionally, it is discovered that the unbroken oxide films on the interface are composed of Mn, Si or Cr at the reductions of 50% and 65%. The SEM fractography of tensile specimen demonstrates that the BTW1 has significant dimple characteristics and possesses lower-sized dimples with the increment in reduction, suggesting that the toughness and bonding strength of the cladding plates would be improved by the increase of reduction. The results reveal that a high rolling reduction causes the interfacial oxide film broken and further forms a higher-sized composite metallurgical bonding interface. The peak microhardness is achieved near the interface.
文摘Hot-rolled wide strip for production of large diameter,heavy gauged(up to 19 mm) helical line pipe grade X80 was a priority development over the last three years.Microstructure,texture and mechanical properties of strips have been characterised.Also the welding conditions have been simulated.The favourable microstructure is achieved by the proper selection of an appropriate chemical composition of low carbon content and increased niobium micro alloying in combination with suitable strictly controlled hot-rolling parameters.The addition of niobium in combination with the adjustment of other alloying elements increases the recrystallisation stop temperature and thus makes it possible to apply a high temperature processing(HTP) concept.The homogeneous bainitic microstructure across the strip gauge is then formed during accelerated cooling on the run-out table of the hot-rolling mill.All results indicated excellent properties of these hot strips which make it suitable for spiral pipes of grade X80 for example 18.9mm×Φ1 220 mm at dimension.
文摘As one of the important categories of hot-rolled products, hot-rolled steel plates for automobile applications generally undergo uniform corrosion or localized corrosion according to different environments of manufacturing, transportation and/or storage of the plates. General corrosion often takes place on the surface of a plate in the exterior part of a package, and only reduces the thickness of the plate and slightly increases the roughness of the surface; however, localized corrosion on the surface of a plate inside the package is likely to result in the formation of pit-like defects on the substrate of the plate, which cannot be removed thoroughly by normal acid pickling or sand blasting, and affects the application of the plate. This research report analyzes the phenomena and characteristics of the rusting behavior of hot- rolled steel plates for automobile applications, and the influencing factors are summaried. The corresponding preventative measures are proposed.
文摘In order to master mechanical property, surface quality and microstructure of constraint cooling (CC) coils undervarious water cooling parameters, more than 100 coils cooling experiments were done with real production process,of which is designed a cooling experimental instrument in the end. The experiments show that high initial coolingtemperature, discontinuous cooling style, and long cooling time can improve mechanical property of cooling coilsand shorten cooling time. The CC coils experiments cover the different steel grades, so that CC process effects onhot-rolled coils may be predicted and controlled actively.
文摘Influence of thermo-mechanical controlled processing(TMCP),including two-stage rolling with laminar cooling,air cooling and ultra-fast cooling,on the microstructure and mechanical properties of three kinds of Nb-microalloeyed steels was investigated by hot-rolling experiment.Effect of chemistry compositions and microstructure on mechanical properties and the relationship between the multiphase microstructure' s formation with TMCP were analyzed.The results showed that the mixed microstructure containing ferrite,bainite,martensite and a small amount of retained austenite can be obtained by thermo-mechanical controlled processing.Size, quantity and distribution of the constituents(ferrite grain,bainite packet and M-A islands) significantly affect the mechanical properties of three kinds of Nb-microalloyed steels.Under the condition of similar TMCP parameters, there is a gradually decreasing tendency in tensile strength from high silicon Nb steel,high silicon Nb-Ti steel to low silicon Nb-Ti steel,and an opposite tendency in total elongation and product of tensile strength and ductility. Total elongation and product of tensile strength and ductility reach the maximum values(41%and 25256 MPa% respectively) for low silicon Nb-Ti steel.
文摘In this study, the welding technology of the hot-rolled extra-high-strength steel, BS960QC, has been comprehensively investigated. Analysis has been made on the weldability ,the different welding procedures ,the mechanical properties, and the fatigue properties, and a set of recommendation guidelines have been proposed for evaluating the welded joints of the extra-high-strength steel. The research and results indicate that the hot-rolled extra-high-strength steel, BS960QC,has good weldability and an excellent adaptability to welding procedures. Further,the excellent mechanical properties and fatigue properties of the welded joints ,which can be achieved by using optimized welding procedures, can completely meet the technical requirements of the construction machinery industry.
文摘The patenting process of three hot-rolled steels with carbon mass contents of 0.70%-0. 90% was studied. The effect of the quenching temperature on the cementite lamellar distance in the steel was evaluated on the basis of microstructural characterization and mechanical property tests. The patenting treatment of high-carbon hot- rolled strip and its application in springs were discussed.
基金supported by the Key Research Foundation of Baoshan Iron & Steel Co.,Ltd.(No.D06EBEA207)
文摘Results presented in this study contribute to investigation of the microstructure and mechanical properties of the hot-rolled Fe16Mn0.6C steel plates.The steel plates have been produced by being hot-rolled at temperatures ranging from 1100℃ to 850℃ in seven passes to 97.5% reduction in thickness and then cooled in a furnace of 650℃.Some plates have been annealed at temperatures ranging from 300℃ to 1100℃ for 5min to 60min,and then followed by water quenching.There are annealing twins in the hot-rolled Fe16Mn0.6C steel.Fe16Mn0.6C steel presents similar ductile behavior as X-IPTM steel,but much higher elongation than commercial martensitic steel (MP) 1000,dual phase (DP) 980,and transformation induced plasticity (TRIP) 980 steels.Fe16Mn0.6C steel experiences γε (-α) transformation in some local regions,but remains mostly austenite during the entire deformation process.Fe16Mn0.6C steel with special mechanical properties can be produced by using the appropriate anneal technology.Twinning induced plasticity(TWIP) effect only occurs in the Fe16Mn0.6C steel annealed at temperature higher than 900℃.
文摘The critical transformation temperatures,A_(c1) and A_(c3),of a hot-rolled low-carbon titanium microalloyed steel were determined as a part of an examination of its phase-transformation behavior. Austenite decomposition during the continuous cooling of the titanium microalloyed steel was studied by heating it to 1 250 ℃,cooling it to 880 ℃,holding for 2 s,and then cooling it to room temperature at different cooling rates. The transformation kinetics( CCT curve) was characterized as well.
文摘In this study, the matrix structure, state and composition of the mill scales of four typical domestically made 510L hot-rolled strips were observed and analyzed by means of optical microscopy (OM) ,scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion behavior of the steels with and without mill scales were investigated by means of hot-humid corrosion tests under the condition of relative humidity ( RH ) of 95% at 50℃ and 70℃, respectively. The results show that the matrix structures, state, composition and thickness of mill scales vary in the strips. The rusting starting time of the specimens with scales is generally a bit longer than that of the specimens without scales, but their corrosion mass-gain is higher. For these two kinds of specimens ,their corrosion rate increases significantly with the increase of temperature. The rusting behavior of the 510L strips produced by various plants is different due to the variations of hot-rolling processes and designed chemical compositions. Various relevant aspects should be taken into account in the evaluation of the corrosion behavior of hot-rolled strips.