Currently, when magnesium alloy sheet is rolled, the method of controlling roll temperature is simple and inaccurate. Furthermore, roll temperature has a large influence on the quality of magnesium alloy sheet; theref...Currently, when magnesium alloy sheet is rolled, the method of controlling roll temperature is simple and inaccurate. Furthermore, roll temperature has a large influence on the quality of magnesium alloy sheet; therefore, a new model using circular fluid flow control roll temperature has been designed. A fluid heat transfer structure was designed, the heat transfer process model of the fluid heating roll was simplified, and the finite di erence method was used to cal?culate the heat transfer process. Fluent software was used to simulate the fluid?solid coupling heat transfer, and both the trend and regularity of the temperature field in the heat transfer process were identified. The results show that the heating e ciency was much higher than traditional heating methods(when the fluid heat of the roll and tempera?ture distribution of the roll surface was more uniform). Moreover, there was a bigger temperature di erence between the input and the output, and after using reverse flow the temperature di erence decreased. The axial and circum?ferential temperature distributions along the sheet were uniform. Both theoretical calculation results and numerical simulation results of the heat transfer between fluid and roll were compared. The error was 1.8%–12.3%, showing that the theoretical model can both forecast and regulate the temperature of the roll(for magnesium alloy sheets) in the rolling process.展开更多
A water model and a high-speed video camera were utilized in the 300-t RH equipment to study the effect of steel flow patterns in a vacuum chamber on fast decarburization and a superior flow-pattern map was obtained d...A water model and a high-speed video camera were utilized in the 300-t RH equipment to study the effect of steel flow patterns in a vacuum chamber on fast decarburization and a superior flow-pattern map was obtained during the practical RH process. There are three flow patterns with different bubbling characteristics and steel surface states in the vacuum chamber: boiling pattern(BP), transition pattern(TP), and wave pattern(WP). The effect of the liquid-steel level and the residence time of the steel in the chamber on flow patterns and decarburization reaction were investigated, respectively. The liquid-steel level significantly affected the flow-pattern transition from BP to WP, and the residence time and reaction area were crucial to evaluate the whole decarburization process rather than the circulation flow rate and mixing time. A superior flow-pattern map during the practical RH process showed that the steel flow pattern changed from BP to TP quickly, and then remained as TP until the end of decarburization.展开更多
In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then...In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then, the constitutive relation was established based on Arrhenius-type hyperbolic sine equation. The results demonstrated that the flow stress depended on the deformation temperature and strain rate. When the deformation temperature kept constant, the flow stress increased as the strain rate increased. When the strain rate remained constant, the flow stress decreased as the temperature increased. The flow stresses calculated by constitutive equations were in a good agreement with experimental results. The apparent activation energy for deformation in the above processing region was estimated to be 369 kJ tool-1. A processing map could be obtained by the superimposition of an instability map on a power dissipation map. Based on the analysis of processing map and the microstructures, the theological instability regimes of strain rate and temperature for hot deformation of wear-resistant steel BTWl had been identified.展开更多
Stainless steel (S S)/carbon steel (C S) clad plates were generated by means of the all-around weld of interface and vacuuming (AAWIV) followed by hot rolling, wherein AAWIV was utilized for controlling the inte...Stainless steel (S S)/carbon steel (C S) clad plates were generated by means of the all-around weld of interface and vacuuming (AAWIV) followed by hot rolling, wherein AAWIV was utilized for controlling the interface oxidation during hot rolling. The structure near the interface was analyzed by optical microscopy (OM), scanning electron mi- croscopy (SEM) and transmission electron microscopy (TEM). The mechanical properties of SS/CS clad plates were investigated by tensile and shear as well as bend tests. The SS/CS interface is relatively flat and no visible separation appears. Line scanning analysis shows that diffusion of Cr and Ni from SS to CS and C from CS to SS occurred during bonding. Higher dislocation densities are observed in both layers of parent plates adhering to the interface. The SS/ CS clad plates reveal higher yield, tensile and shear strengths. Both macroscopic delamination at the interface and fracture of base CS as well as intergranular fracture appearance of flyer plate are observed in the tensile test. The shear specimen fails in a ductile manner and the bend specimen tested shows no visible crack at the interface. Taking both interracial structure and mechanical properties into account, the SS/CS clad plates exhibit sound bonding by the process of AAWIV and hot rolling.展开更多
The inclined six-roll tube straightener is an important equipment for the finishing line.It can not only straighten the steel pipe,but also finish the ovality of the cross section.In the actual straightening process,t...The inclined six-roll tube straightener is an important equipment for the finishing line.It can not only straighten the steel pipe,but also finish the ovality of the cross section.In the actual straightening process,the cross section of the tube is prone to deform,that is,the round ness is not good.The flatteni ng displacement is an import a nt parameter to control cross-section forming of tube.According to the established mechanical model,the analytical calculation equations of the flattening force and the flattening displacement were derived using the energy method.Based on the finite element simulation data,the ratios of the finite element results of the什attening force to the analytical ones were fitted.The correlation coefficient after fitting is greater than 99%,and the fitting effect is excelleni.The flattening experiment was carried out on tubes of different materials and different specifications,and the setting method of the optimal flattening displacement during straightening process was obtained.In the actual straightening process,using this flattening displacement,the ovality of straightened steel tube is less than 0.3%.Therefore,the proposed method can provide a reference for the flattening displacement in the actual straightening process.展开更多
Cu is known to affect the edge cracking characteristics of austenitic stainless steel as it causes embrittlement.The hot rolling test of four kinds of austenitic stainless steel with different copper content(0,2.42,3....Cu is known to affect the edge cracking characteristics of austenitic stainless steel as it causes embrittlement.The hot rolling test of four kinds of austenitic stainless steel with different copper content(0,2.42,3.60 and 4.35 wt.%)was carried out to examine the effect of hot rolling cracks on steel containing different copper contents.The evolution of crack and microstructure was analyzed using the scanning electron microscope,energy-dispersive spectrometer,electron back scattered diffraction and transmission electron microscope.Experimental results showed an upward trend in edge cracking degree when Cu content was 4.35%,and the crack extended from the edge of the steel plate to the middle by about 14 mm.Besides,severe oxidation was observed inside the crack by fractography.With the increase in copper content at 1250℃,the content of{110}<112>brass and{112}<111>copper textures decreased.When the content of copper was 4.35%,the decrease was most significant,and{112}<111>copper texture content decreased to only 0.5%.Generally,the textures of 2.42%Cu and 3.60%Cu 304L steel changed little,while a large change in the texture of 4.35%Cu 304L steel was observed.To conclude,the increase in rolling temperature can prevent edge crack and its propagation effectively.展开更多
The influence of hot rolling on the microstructure and subsequent mechanical characteristics of explosive-welded ferritic stainless steel (FSS)/carbon steel (CS) laminate was investigated. The results indicate tha...The influence of hot rolling on the microstructure and subsequent mechanical characteristics of explosive-welded ferritic stainless steel (FSS)/carbon steel (CS) laminate was investigated. The results indicate that by hot rolling, decarburization layer disappears and a uniform structure is gained in CS side, but ferrite grains and carbides in constituent FSS form an uneven band microstructure which is denser at superficial zone than near the interface. The transmission electron microscopy results indicate that the layers adhering to the interface show typical deformed microstructure features, i.e., stream-like strips and elongated grains in FSS plates, carbide precipitates and bended cementite fragments in CS plates; and high-density dislocations in both plates, With hot rolling, various mechanical strengths and hardness are increased, while the elongation percentage is diminished. Examination of fractographs from tensile tests reveals predominately small dimples for explosive-welded specimens, whereas both big dimples and cleavage fracture for rolled specimens. Stereomicroscopic fractographs taken on shear samples indicate that the surfaces of explosive-welded specimens exhibit uniform deformation, but uneven deformation is displayed for that of rolled specimens. These results indicate that hot rolling is beneficial to improve the strength of explosive-welded FSS/CS laminate but not good for enhancing its plasticity.展开更多
基金National Natural Science Foundation of China(Grant No.U1510131)Key Research and Development Projects of Shanxi Province of China(Grant Nos.201603D121010,201603D111004)+3 种基金Science and Technology Project of Jin Cheng City of China(Grant No.20155010)Youth Program of National Natural Science Fund of China(Grant No.51604181)Project of Young Scholar of Shanxi ProvinceLeading Talent Project of Innovative Entrepreneurial Team of Jiangsu Province(Grant No.51501122)
文摘Currently, when magnesium alloy sheet is rolled, the method of controlling roll temperature is simple and inaccurate. Furthermore, roll temperature has a large influence on the quality of magnesium alloy sheet; therefore, a new model using circular fluid flow control roll temperature has been designed. A fluid heat transfer structure was designed, the heat transfer process model of the fluid heating roll was simplified, and the finite di erence method was used to cal?culate the heat transfer process. Fluent software was used to simulate the fluid?solid coupling heat transfer, and both the trend and regularity of the temperature field in the heat transfer process were identified. The results show that the heating e ciency was much higher than traditional heating methods(when the fluid heat of the roll and tempera?ture distribution of the roll surface was more uniform). Moreover, there was a bigger temperature di erence between the input and the output, and after using reverse flow the temperature di erence decreased. The axial and circum?ferential temperature distributions along the sheet were uniform. Both theoretical calculation results and numerical simulation results of the heat transfer between fluid and roll were compared. The error was 1.8%–12.3%, showing that the theoretical model can both forecast and regulate the temperature of the roll(for magnesium alloy sheets) in the rolling process.
基金financially supported by the National Natural Science Foundation of China (No.51704203)the PhD Early Development Program of Taiyuan University of Science and Technology (Nos. 20152008, 20152013, and 20152018)+2 种基金Shanxi Province Science Foundation for Youths (No. 201601D202027)Key Project of Research and Development Plan of Shanxi Province (Nos. 201603D111004 and 201603D121010)NSFC-Shanxi Coal Based Low Carbon Joint Fund (No. U1510131)
文摘A water model and a high-speed video camera were utilized in the 300-t RH equipment to study the effect of steel flow patterns in a vacuum chamber on fast decarburization and a superior flow-pattern map was obtained during the practical RH process. There are three flow patterns with different bubbling characteristics and steel surface states in the vacuum chamber: boiling pattern(BP), transition pattern(TP), and wave pattern(WP). The effect of the liquid-steel level and the residence time of the steel in the chamber on flow patterns and decarburization reaction were investigated, respectively. The liquid-steel level significantly affected the flow-pattern transition from BP to WP, and the residence time and reaction area were crucial to evaluate the whole decarburization process rather than the circulation flow rate and mixing time. A superior flow-pattern map during the practical RH process showed that the steel flow pattern changed from BP to TP quickly, and then remained as TP until the end of decarburization.
基金This work was supported by the National Natural Science Foundation of China (No. U1510131) and the Applied Basic Research Project of Shanxi Province (Nos. 201701D121078 and 201701D221143).
文摘In order to predict flow instability of wear-resistant steel BTW1, the hot compressions of wear-resistant steel BTW1 were firstly performed at the temperature of 900-1150 ℃ and at the strain rate of 0.05-15 s-1. Then, the constitutive relation was established based on Arrhenius-type hyperbolic sine equation. The results demonstrated that the flow stress depended on the deformation temperature and strain rate. When the deformation temperature kept constant, the flow stress increased as the strain rate increased. When the strain rate remained constant, the flow stress decreased as the temperature increased. The flow stresses calculated by constitutive equations were in a good agreement with experimental results. The apparent activation energy for deformation in the above processing region was estimated to be 369 kJ tool-1. A processing map could be obtained by the superimposition of an instability map on a power dissipation map. Based on the analysis of processing map and the microstructures, the theological instability regimes of strain rate and temperature for hot deformation of wear-resistant steel BTWl had been identified.
基金Item Sponsored by National Key Technology Research and Development Program in 12th Five-year Plan of China(2012CB722801)National Natural Science Foundation of China(51105264)Postdoctoral Science Foundation of China(2012M520677)
文摘Stainless steel (S S)/carbon steel (C S) clad plates were generated by means of the all-around weld of interface and vacuuming (AAWIV) followed by hot rolling, wherein AAWIV was utilized for controlling the interface oxidation during hot rolling. The structure near the interface was analyzed by optical microscopy (OM), scanning electron mi- croscopy (SEM) and transmission electron microscopy (TEM). The mechanical properties of SS/CS clad plates were investigated by tensile and shear as well as bend tests. The SS/CS interface is relatively flat and no visible separation appears. Line scanning analysis shows that diffusion of Cr and Ni from SS to CS and C from CS to SS occurred during bonding. Higher dislocation densities are observed in both layers of parent plates adhering to the interface. The SS/ CS clad plates reveal higher yield, tensile and shear strengths. Both macroscopic delamination at the interface and fracture of base CS as well as intergranular fracture appearance of flyer plate are observed in the tensile test. The shear specimen fails in a ductile manner and the bend specimen tested shows no visible crack at the interface. Taking both interracial structure and mechanical properties into account, the SS/CS clad plates exhibit sound bonding by the process of AAWIV and hot rolling.
基金National Key Research and Development Program of China(Grant No.2018YFB1308700)Applied Basic Research Programs of Shanxi Province(Grant Nos.201901D111244 and 201901D211311)Major Science and Technology Projects of Shanxi Province(Grant No.20181102016).
文摘The inclined six-roll tube straightener is an important equipment for the finishing line.It can not only straighten the steel pipe,but also finish the ovality of the cross section.In the actual straightening process,the cross section of the tube is prone to deform,that is,the round ness is not good.The flatteni ng displacement is an import a nt parameter to control cross-section forming of tube.According to the established mechanical model,the analytical calculation equations of the flattening force and the flattening displacement were derived using the energy method.Based on the finite element simulation data,the ratios of the finite element results of the什attening force to the analytical ones were fitted.The correlation coefficient after fitting is greater than 99%,and the fitting effect is excelleni.The flattening experiment was carried out on tubes of different materials and different specifications,and the setting method of the optimal flattening displacement during straightening process was obtained.In the actual straightening process,using this flattening displacement,the ovality of straightened steel tube is less than 0.3%.Therefore,the proposed method can provide a reference for the flattening displacement in the actual straightening process.
基金The project was supported by the National Key Research and Development Program of China(2016YFB0300205)Taiyuan University of Science and Technology Postdoctoral Research Startup Fund(20192024)+5 种基金Natural Science Foundation of Liaoning Province(No.2019-KF-25-05)the Shanxi Province Science Foundation for Youths(201801D221120)the Key Research and Development Program of Shanxi Province(201703D111003)the Taiyuan University of Science and Technology Scientific Research Initial Funding(20172014)Shanxi Outstanding Doctorate Award Funding Fund(20182061)the Coordinative Innovation Center of Taiyuan Heavy Machinery Equipment.Author information。
文摘Cu is known to affect the edge cracking characteristics of austenitic stainless steel as it causes embrittlement.The hot rolling test of four kinds of austenitic stainless steel with different copper content(0,2.42,3.60 and 4.35 wt.%)was carried out to examine the effect of hot rolling cracks on steel containing different copper contents.The evolution of crack and microstructure was analyzed using the scanning electron microscope,energy-dispersive spectrometer,electron back scattered diffraction and transmission electron microscope.Experimental results showed an upward trend in edge cracking degree when Cu content was 4.35%,and the crack extended from the edge of the steel plate to the middle by about 14 mm.Besides,severe oxidation was observed inside the crack by fractography.With the increase in copper content at 1250℃,the content of{110}<112>brass and{112}<111>copper textures decreased.When the content of copper was 4.35%,the decrease was most significant,and{112}<111>copper texture content decreased to only 0.5%.Generally,the textures of 2.42%Cu and 3.60%Cu 304L steel changed little,while a large change in the texture of 4.35%Cu 304L steel was observed.To conclude,the increase in rolling temperature can prevent edge crack and its propagation effectively.
基金This research was funded by the National Natural Science Foundation of China under Grant No. U 1510131, the Key Research and Development Program of Shanxi Province under Grant Nos. 201603D121010 and 201603D111004 and Shanxi Young Scholars Program.
文摘The influence of hot rolling on the microstructure and subsequent mechanical characteristics of explosive-welded ferritic stainless steel (FSS)/carbon steel (CS) laminate was investigated. The results indicate that by hot rolling, decarburization layer disappears and a uniform structure is gained in CS side, but ferrite grains and carbides in constituent FSS form an uneven band microstructure which is denser at superficial zone than near the interface. The transmission electron microscopy results indicate that the layers adhering to the interface show typical deformed microstructure features, i.e., stream-like strips and elongated grains in FSS plates, carbide precipitates and bended cementite fragments in CS plates; and high-density dislocations in both plates, With hot rolling, various mechanical strengths and hardness are increased, while the elongation percentage is diminished. Examination of fractographs from tensile tests reveals predominately small dimples for explosive-welded specimens, whereas both big dimples and cleavage fracture for rolled specimens. Stereomicroscopic fractographs taken on shear samples indicate that the surfaces of explosive-welded specimens exhibit uniform deformation, but uneven deformation is displayed for that of rolled specimens. These results indicate that hot rolling is beneficial to improve the strength of explosive-welded FSS/CS laminate but not good for enhancing its plasticity.