The effects of thermomechanical treatment on the properties and microstructure of Cu-Cr-Zr alloy and Cu-Cr-Zr-Ag alloy were investigated. Ag addition improves the mechanical properties of the alloy through solid solut...The effects of thermomechanical treatment on the properties and microstructure of Cu-Cr-Zr alloy and Cu-Cr-Zr-Ag alloy were investigated. Ag addition improves the mechanical properties of the alloy through solid solution strengthening and brings a little effect on the electrical conductivity of the alloy. A new Cu-Cr-Zr-Ag alloy was developed, which has an excellent combination of the tensile strength, elongation, and electrical conductivity reaching 476.09 MPa, 15.43% and 88.68% IACS respectively when subjected to the optimum thermomechanical treatment, i.e., solution-treating at 920℃ for 1 h, cold drawing to 96% deformation, followed by aging at 400℃ for 3 h. TEM analysis revealed two kinds of finely dispersed precipitates of Cr and CuaZr. It is very important to use the mechanisms of solid solution strengthening, work hardening effect as well as precipitate pinning effect of dislocations to improve tensile strength of the alloy without adversely affecting its electrical conductivity.展开更多
The mechanical properties and microstructures of 6013 alloy after different thermomechanical treatments were investigated. The detailed dislocation configurations after deformation and morphologies of age hardening pr...The mechanical properties and microstructures of 6013 alloy after different thermomechanical treatments were investigated. The detailed dislocation configurations after deformation and morphologies of age hardening precipitates were examined through transmission electron microscopy (TEM). The experimental results show that the thermomechanical treatment can significantly enhance the strength of 6013 alloy, and has a similar influence trend on single and two-step aging behaviors. With the increasing deformation ratio, the peak-hardness (HVmax) increases, the time to HV shortens, and the density of tangled dislocation network increases. The aging precipitates become larger and inhomogeneous by applying thernomechanical treatment.展开更多
Due to their high specific strength and low density, magnesium alloys are widely used in many weight-saving applications. This research is aimed at investigating the microstructure and hardness of commercial AZ63 allo...Due to their high specific strength and low density, magnesium alloys are widely used in many weight-saving applications. This research is aimed at investigating the microstructure and hardness of commercial AZ63 alloy specimens subjected to two different thermomechanical treatments (TMTs). For the first TMT, after solution treated at the temperature of 380 ℃ for 20 h, AZ63 alloy specimens were 5% cold worked by rolling process followed by ageing at the temperatures of 150 ℃and 250 ℃ for 3, 9 and 25 h. In the second TMT, the specimens were solution treated at the temperature of 380 ℃ for 20 h, underwent 2% cold worked and quenched in water of 0 ℃. Half of the specimens were then 2% cold worked whilst the rest were rolled to 8% cold worked. All the specimens were then aged at the temperatures of 150 ℃ and 250 ℃ for 3, 9 and 25 h. Optical microscope was used to analyze the microstructures of the specimens. Hardness test was too conducted to measure the effect of the treatments on the specimens. Results show that two-step aging enhances the hardness of the specimens due to the distribution of fine β-phase (MglTA112) in the alloy matrix. The results also reveal that, the best hardness from the first TMT was produced by specimen that was pre-aged at 150 ℃ whereas, in the second TMT, aging at 250 ℃ exhibited the best hardness values.展开更多
The microstructure and mechanical properties of an as-cast Mg-4.0Sm-1.0Ca alloy were investigated during thermome-chanical treatments consisting of hot extrusion, rolling, and aging at 473 K. Mg41Sm5 phases containing...The microstructure and mechanical properties of an as-cast Mg-4.0Sm-1.0Ca alloy were investigated during thermome-chanical treatments consisting of hot extrusion, rolling, and aging at 473 K. Mg41Sm5 phases containing Ca and needle-like Mg2Ca phases formed in the Mg matrix, and the average grain size and elongation were 4.2μm and 27%, respectively, after hot extrusion, which implied an increase in ductility. In addition, after the rolling, the grain size was further refined, and the tensile strength in-creased to 293 MPa. A new precipitate Mg3Sm was found in the peak-aged Mg-4.0Sm-1.0Ca alloy and this alloy displayed the best mechanical properties, with a peak hardness of 83 HV and ultimate tensile strength of 313 MPa; these properties were attributed to grain refinement strengthening, solid solution strengthening, work hardening, and precipitation strengthening.展开更多
Various solid state phase transformations exist in metastable β-type Ti alloys,which can be employed to optimize the mechanical properties.In this paper,synchrotron X-ray diffraction(SXRD)experiments were carried out...Various solid state phase transformations exist in metastable β-type Ti alloys,which can be employed to optimize the mechanical properties.In this paper,synchrotron X-ray diffraction(SXRD)experiments were carried out to study the phase transformations of a Ti36Nb5Zr alloy subjected to different thermomechanical treatments.Furthermore,the correlation between the phase constitutions and the mechanical properties was discussed.The a" texture formed,and high-density defects were introduced after cold rolling of the solution treated specimen,leading to the decrease in Young’s modulus and the increase in strength.The cold-rolled specimens were then annealed at temperatures from 423 to 773 K for 30 min.Both the Young’s modulus and strength increased with annealing temperatures increasing up to 673 K,which resulted from the precipitation of the ω and/or α phases.With further increase in annealing temperatures to 773 K,the β→α precipitation replaced the β→ω_(iso) phase transformation,and the density of defects decreased,leading to the decrease in both the Young’s modulus and strength.These results provide theoretical basis for the design biomedical Ti alloys with both low Young’s modulus and high strength.展开更多
Modified CCT diagram of carbide-flee bainite-martensite (CFB/M) ultra-high strength steel was established by applying controlled cooling of small samples. In addition, the influence of thermomechanical treatment tem...Modified CCT diagram of carbide-flee bainite-martensite (CFB/M) ultra-high strength steel was established by applying controlled cooling of small samples. In addition, the influence of thermomechanical treatment tem- perature on the structure and properties was discussed. The experimental results showed that when deformed at 860℃ and below, ferrite transformation occurred due to strain. With the decrease of ausforming temperature, the quantity of ferrite increased and strength and toughness were deteriorated. Therefore, certain information was provided for optimizing technical parameter of ausforming process., firstly, the thermomechanical treatment temperature should not be lower than 860 ℃ in order to avoid ferrite formation induced by deformation; secondly, rapid cooling rate is also significant after deformation in order to avoid ferrite precipitation during subsequent cooling stage.展开更多
The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned ...The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned along the plastic deformation direction were obtained by six-pass drawing in the solution heat treatment state.The introducing of high-density dislocations in Al matrix by multiple drawing resulted in enhanced nucleation of precipitates and subsequent uniform growth during ageing.Consequently,ultra-strength GNP/2024Al composites,with yield and ultimate tensile strength 482 and571 MPa,respectively,were achieved.The high strength was attributed to homogeneous dispersion of undamaged GNPs,fine and dispersed precipitations and work-hardening effect.This work demonstrated that TMT could act as a feasible strategy for preparing high-performance GNP/Al composites.展开更多
Thermomechanical cyclic quenching and tempering(TMCT)can strengthen steels through a grain size reduction mechanism.The effect of TMCT on microstructure,mechanical,and electrochemical properties of AISI 1345 steel was...Thermomechanical cyclic quenching and tempering(TMCT)can strengthen steels through a grain size reduction mechanism.The effect of TMCT on microstructure,mechanical,and electrochemical properties of AISI 1345 steel was investigated.Steel samples heated to 1050℃,rolled,quenched to room temperature,and subjected to various cyclic quenching and tempering heat treatments were named TMCT-1,TMCT-2,and TMCT-3 samples,respectively.Microstructure analysis revealed that microstructures of all the treated samples contained packets and blocks of well-refined lath-shaped martensite and retained austenite phases with varying grain sizes(2.8–7.9μm).Among all the tested samples,TMCT-3 sample offered an optimum combination of properties by showing an improvement of 40%in tensile strength and reduced 34%elongation compared with the non-treated sample.Nanoindentation results were in good agreement with mechanical tests as the TMCT-3 sample exhibited a 51%improvement in indentation hardness with almost identical reduced elastic modulus compared with the non-treated sample.The electrochemical properties were analyzed in 0.1 M NaHCO_(3) solution by potentiodynamic polarization and electrochemical impedance spectroscopy.As a result of TMCT,the minimum corrosion rate was 0.272 mm/a,which was twenty times less than that of the nontreated sample.The impedance results showed the barrier film mechanism,which was confirmed by the polarization results as the current density decreased.展开更多
Controlling the precipitation through thermomechanical treatment is an important method to improve the corrosion resistance of Al–Cu–Mg alloys. In this study, the corrosion behaviors of Al–Cu–Mg alloys in the solu...Controlling the precipitation through thermomechanical treatment is an important method to improve the corrosion resistance of Al–Cu–Mg alloys. In this study, the corrosion behaviors of Al–Cu–Mg alloys in the solution-treated state and retrogressiontreated state under cold rolling deformation and then natural aging were investigated. In the solution-treated series alloys, the cold-rolled deformation improved the resistance to intergranular corrosion by suppressing the precipitation of the S-phase on the grain boundaries. The increased pitting potential and corrosion potential were related to the increased concentration of solute atoms within the grain interiors and the eliminated S-phase on grain boundaries. In the retrogression-treated series alloys, the 30% cold rolling deformation stimulated the growth of the S-phase and transformed the S-phase distribution from discontinuous to continuous on the grain boundaries, thereby changing the pitting corrosion to the network corrosion morphology. The precipitation of the S-phase with large dimension within the grain interiors contributed to the decreased pitting potential and corrosion potential.展开更多
The method controlling grain shape in TMT processing and the effect of grain shape on char- acteristic parameters in superplastic deformation were discussed.The accommodation velocity of grahl boundary sliding,which i...The method controlling grain shape in TMT processing and the effect of grain shape on char- acteristic parameters in superplastic deformation were discussed.The accommodation velocity of grahl boundary sliding,which is the dominant mechanism in superplastic deformation,and the contribution of each mechanism to the total strain,as influenced by grain shape,were ana- lyzed.Grain shape has been shown to be an essential structural factor for superplasticity.Then an analysis was made about the effect of grain shape on the region transition strain rate so that a new concept,critical aspect for superplasticity,was worked out.These predictions were compared with the measured results in an Al-Zn-Mg alloy.展开更多
The superplasticity of high strength superhard A1 alloy LC4 was improved to a great extent by modified thermomechanical treatment.Its maximum elongation may be up to 2100% un- der deformation at initial strain rate of...The superplasticity of high strength superhard A1 alloy LC4 was improved to a great extent by modified thermomechanical treatment.Its maximum elongation may be up to 2100% un- der deformation at initial strain rate of 8.33×10^(-4) S^(-1) at 510℃.Observations of the microstructure changes revealed that with the increase of the deformation,the grain grows and the alloy exhibits strain hardening.The excellent elongation of the alloy seems due to the in- crease of grain stability under deformation.展开更多
The dislocation ledges at the α2/7 intedece in a hot-dejormed Ti-45Al-10N alloywere analyzed by high-resolution tmnsmission electron microscopy. A new type ofdislocation ledge containing 1/3[111] Frank partial was fo...The dislocation ledges at the α2/7 intedece in a hot-dejormed Ti-45Al-10N alloywere analyzed by high-resolution tmnsmission electron microscopy. A new type ofdislocation ledge containing 1/3[111] Frank partial was found. The height of the ledgestDas always three [111]γplanes. The Burpers vectore of these diBlocation ledges weredetermined to be 1/2[110] and 1/2<101] corresponding to the 90 dey. and 30 deg.Shockley partials at noral ledges, i.e. 90 dep. ShockIey Partial dislocation +1/3[111]Frank partial dislocation; and 30 deg. Shockley partial dislocation + 1/3[111] Frankparfial dislocations. The jormation mechanism of this new tare of dislocation ledgewas discussed.展开更多
The paper deals with investigations concerning the structure and state of dispersive precipitations of the phases consolidating in the high-strength steel Weldox 1300 after its high temperature thermomechanical treatm...The paper deals with investigations concerning the structure and state of dispersive precipitations of the phases consolidating in the high-strength steel Weldox 1300 after its high temperature thermomechanical treatment.Making use of transmission technique of electron microscopy (TEM) mainly the microstructure and morphology of martensite was analysed,as well as the state of dispersive precipitations of carbides and nitrides resulting from microadditives of such alloys as Nb,V,Ti or B,introduced into the steel.Observations revealed both a fine lathed and twin structure of the matrix of martensite in the investigated steel.By means of the method of electron diffraction particles of secondary strengthening phases of the M(C,N) type of a nanocrystalline size could be identified,and also non-metallic oxide inclusions,affecting the mechanism of strengthening of the investigated steel.展开更多
The article describes principles of developing steels for maritime structures and main pipelines.The scientific approach lies in forming an ultra fine-grained and submicrocrystal structure through thermomechanical tre...The article describes principles of developing steels for maritime structures and main pipelines.The scientific approach lies in forming an ultra fine-grained and submicrocrystal structure through thermomechanical treatment of low-carbon low-alloyed steels,providing higher strength and resistance to brittle fracture.The article presents results of assessing the operability characteristics and introducing new steels.展开更多
基金financially supported by the National High-Tech Research and Development Program of China (No.2006AA03Z522)the National Natural Science Foundation of China (No.50704006)the Technology De-velopment Fund of CHALCO (No.CHINACO-2009-KJ-02)
文摘The effects of thermomechanical treatment on the properties and microstructure of Cu-Cr-Zr alloy and Cu-Cr-Zr-Ag alloy were investigated. Ag addition improves the mechanical properties of the alloy through solid solution strengthening and brings a little effect on the electrical conductivity of the alloy. A new Cu-Cr-Zr-Ag alloy was developed, which has an excellent combination of the tensile strength, elongation, and electrical conductivity reaching 476.09 MPa, 15.43% and 88.68% IACS respectively when subjected to the optimum thermomechanical treatment, i.e., solution-treating at 920℃ for 1 h, cold drawing to 96% deformation, followed by aging at 400℃ for 3 h. TEM analysis revealed two kinds of finely dispersed precipitates of Cr and CuaZr. It is very important to use the mechanisms of solid solution strengthening, work hardening effect as well as precipitate pinning effect of dislocations to improve tensile strength of the alloy without adversely affecting its electrical conductivity.
基金Funded by the National Key Technology R&D Program of China(No.2007BAE38B01)
文摘The mechanical properties and microstructures of 6013 alloy after different thermomechanical treatments were investigated. The detailed dislocation configurations after deformation and morphologies of age hardening precipitates were examined through transmission electron microscopy (TEM). The experimental results show that the thermomechanical treatment can significantly enhance the strength of 6013 alloy, and has a similar influence trend on single and two-step aging behaviors. With the increasing deformation ratio, the peak-hardness (HVmax) increases, the time to HV shortens, and the density of tangled dislocation network increases. The aging precipitates become larger and inhomogeneous by applying thernomechanical treatment.
文摘Due to their high specific strength and low density, magnesium alloys are widely used in many weight-saving applications. This research is aimed at investigating the microstructure and hardness of commercial AZ63 alloy specimens subjected to two different thermomechanical treatments (TMTs). For the first TMT, after solution treated at the temperature of 380 ℃ for 20 h, AZ63 alloy specimens were 5% cold worked by rolling process followed by ageing at the temperatures of 150 ℃and 250 ℃ for 3, 9 and 25 h. In the second TMT, the specimens were solution treated at the temperature of 380 ℃ for 20 h, underwent 2% cold worked and quenched in water of 0 ℃. Half of the specimens were then 2% cold worked whilst the rest were rolled to 8% cold worked. All the specimens were then aged at the temperatures of 150 ℃ and 250 ℃ for 3, 9 and 25 h. Optical microscope was used to analyze the microstructures of the specimens. Hardness test was too conducted to measure the effect of the treatments on the specimens. Results show that two-step aging enhances the hardness of the specimens due to the distribution of fine β-phase (MglTA112) in the alloy matrix. The results also reveal that, the best hardness from the first TMT was produced by specimen that was pre-aged at 150 ℃ whereas, in the second TMT, aging at 250 ℃ exhibited the best hardness values.
基金supported by the Nature Science Foundation of Shanxi Province(201401115-3,2015011038)
文摘The microstructure and mechanical properties of an as-cast Mg-4.0Sm-1.0Ca alloy were investigated during thermome-chanical treatments consisting of hot extrusion, rolling, and aging at 473 K. Mg41Sm5 phases containing Ca and needle-like Mg2Ca phases formed in the Mg matrix, and the average grain size and elongation were 4.2μm and 27%, respectively, after hot extrusion, which implied an increase in ductility. In addition, after the rolling, the grain size was further refined, and the tensile strength in-creased to 293 MPa. A new precipitate Mg3Sm was found in the peak-aged Mg-4.0Sm-1.0Ca alloy and this alloy displayed the best mechanical properties, with a peak hardness of 83 HV and ultimate tensile strength of 313 MPa; these properties were attributed to grain refinement strengthening, solid solution strengthening, work hardening, and precipitation strengthening.
基金This work was financially supported by the Fundamental Research Funds for the Central Universities(No.2017QNA04)Qing-Kun Meng thanks Prof.Yu-Chen Karen Chen-Wiegart at Stony Brook University and Dr.Jian-Ming Bai,Dr.Hui Zhong and Dr.Sanjit Ghose at National Synchrotron Light Source II for their assistance in the synchrotron experiments.This research used 28-ID-2(XPD)beamline of the National Synchrotron Light Source II,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No.DE-SC0012704.
文摘Various solid state phase transformations exist in metastable β-type Ti alloys,which can be employed to optimize the mechanical properties.In this paper,synchrotron X-ray diffraction(SXRD)experiments were carried out to study the phase transformations of a Ti36Nb5Zr alloy subjected to different thermomechanical treatments.Furthermore,the correlation between the phase constitutions and the mechanical properties was discussed.The a" texture formed,and high-density defects were introduced after cold rolling of the solution treated specimen,leading to the decrease in Young’s modulus and the increase in strength.The cold-rolled specimens were then annealed at temperatures from 423 to 773 K for 30 min.Both the Young’s modulus and strength increased with annealing temperatures increasing up to 673 K,which resulted from the precipitation of the ω and/or α phases.With further increase in annealing temperatures to 773 K,the β→α precipitation replaced the β→ω_(iso) phase transformation,and the density of defects decreased,leading to the decrease in both the Young’s modulus and strength.These results provide theoretical basis for the design biomedical Ti alloys with both low Young’s modulus and high strength.
基金Item Sponsored by National Key Fundamental Research and Development Programme of China(2004CB619105)
文摘Modified CCT diagram of carbide-flee bainite-martensite (CFB/M) ultra-high strength steel was established by applying controlled cooling of small samples. In addition, the influence of thermomechanical treatment tem- perature on the structure and properties was discussed. The experimental results showed that when deformed at 860℃ and below, ferrite transformation occurred due to strain. With the decrease of ausforming temperature, the quantity of ferrite increased and strength and toughness were deteriorated. Therefore, certain information was provided for optimizing technical parameter of ausforming process., firstly, the thermomechanical treatment temperature should not be lower than 860 ℃ in order to avoid ferrite formation induced by deformation; secondly, rapid cooling rate is also significant after deformation in order to avoid ferrite precipitation during subsequent cooling stage.
基金the financial supports from National Key R&D program of China(Grant Number2017YFB0703103)Guangdong Province Key Area R&D Program(Grant Number 2019B010942001)Heilongjiang Touyan Team。
文摘The 5.0 vol.%GNP/2024Al composites were prepared by accumulated shear deformation combined with heat treatment,i.e.the thermomechanical treatment(TMT).The results showed that homogeneous distributed GNPs that aligned along the plastic deformation direction were obtained by six-pass drawing in the solution heat treatment state.The introducing of high-density dislocations in Al matrix by multiple drawing resulted in enhanced nucleation of precipitates and subsequent uniform growth during ageing.Consequently,ultra-strength GNP/2024Al composites,with yield and ultimate tensile strength 482 and571 MPa,respectively,were achieved.The high strength was attributed to homogeneous dispersion of undamaged GNPs,fine and dispersed precipitations and work-hardening effect.This work demonstrated that TMT could act as a feasible strategy for preparing high-performance GNP/Al composites.
文摘Thermomechanical cyclic quenching and tempering(TMCT)can strengthen steels through a grain size reduction mechanism.The effect of TMCT on microstructure,mechanical,and electrochemical properties of AISI 1345 steel was investigated.Steel samples heated to 1050℃,rolled,quenched to room temperature,and subjected to various cyclic quenching and tempering heat treatments were named TMCT-1,TMCT-2,and TMCT-3 samples,respectively.Microstructure analysis revealed that microstructures of all the treated samples contained packets and blocks of well-refined lath-shaped martensite and retained austenite phases with varying grain sizes(2.8–7.9μm).Among all the tested samples,TMCT-3 sample offered an optimum combination of properties by showing an improvement of 40%in tensile strength and reduced 34%elongation compared with the non-treated sample.Nanoindentation results were in good agreement with mechanical tests as the TMCT-3 sample exhibited a 51%improvement in indentation hardness with almost identical reduced elastic modulus compared with the non-treated sample.The electrochemical properties were analyzed in 0.1 M NaHCO_(3) solution by potentiodynamic polarization and electrochemical impedance spectroscopy.As a result of TMCT,the minimum corrosion rate was 0.272 mm/a,which was twenty times less than that of the nontreated sample.The impedance results showed the barrier film mechanism,which was confirmed by the polarization results as the current density decreased.
基金supported by the Science and Technology Innovation Major Project of Ningbo(No.2019B10101)the National Natural Science Foundation of China(Nos.U21B2082,U1860206,51601011,51874023)+1 种基金the Fundamental Research Funds for the Central Universities(No.FRF-TP-20-04B)the Recruitment Program of Global Experts,and the State Grid Scientifi c and Technological Research Program of China(No.5211DS17001X)。
文摘Controlling the precipitation through thermomechanical treatment is an important method to improve the corrosion resistance of Al–Cu–Mg alloys. In this study, the corrosion behaviors of Al–Cu–Mg alloys in the solution-treated state and retrogressiontreated state under cold rolling deformation and then natural aging were investigated. In the solution-treated series alloys, the cold-rolled deformation improved the resistance to intergranular corrosion by suppressing the precipitation of the S-phase on the grain boundaries. The increased pitting potential and corrosion potential were related to the increased concentration of solute atoms within the grain interiors and the eliminated S-phase on grain boundaries. In the retrogression-treated series alloys, the 30% cold rolling deformation stimulated the growth of the S-phase and transformed the S-phase distribution from discontinuous to continuous on the grain boundaries, thereby changing the pitting corrosion to the network corrosion morphology. The precipitation of the S-phase with large dimension within the grain interiors contributed to the decreased pitting potential and corrosion potential.
基金This work was supported by the stae“863 plan”,under Grant No.2002AA331112by the Major Science and Technology Project of Henan Province,China,under Grant No.0122021300.
文摘The method controlling grain shape in TMT processing and the effect of grain shape on char- acteristic parameters in superplastic deformation were discussed.The accommodation velocity of grahl boundary sliding,which is the dominant mechanism in superplastic deformation,and the contribution of each mechanism to the total strain,as influenced by grain shape,were ana- lyzed.Grain shape has been shown to be an essential structural factor for superplasticity.Then an analysis was made about the effect of grain shape on the region transition strain rate so that a new concept,critical aspect for superplasticity,was worked out.These predictions were compared with the measured results in an Al-Zn-Mg alloy.
文摘The superplasticity of high strength superhard A1 alloy LC4 was improved to a great extent by modified thermomechanical treatment.Its maximum elongation may be up to 2100% un- der deformation at initial strain rate of 8.33×10^(-4) S^(-1) at 510℃.Observations of the microstructure changes revealed that with the increase of the deformation,the grain grows and the alloy exhibits strain hardening.The excellent elongation of the alloy seems due to the in- crease of grain stability under deformation.
文摘The dislocation ledges at the α2/7 intedece in a hot-dejormed Ti-45Al-10N alloywere analyzed by high-resolution tmnsmission electron microscopy. A new type ofdislocation ledge containing 1/3[111] Frank partial was found. The height of the ledgestDas always three [111]γplanes. The Burpers vectore of these diBlocation ledges weredetermined to be 1/2[110] and 1/2<101] corresponding to the 90 dey. and 30 deg.Shockley partials at noral ledges, i.e. 90 dep. ShockIey Partial dislocation +1/3[111]Frank partial dislocation; and 30 deg. Shockley partial dislocation + 1/3[111] Frankparfial dislocations. The jormation mechanism of this new tare of dislocation ledgewas discussed.
文摘The paper deals with investigations concerning the structure and state of dispersive precipitations of the phases consolidating in the high-strength steel Weldox 1300 after its high temperature thermomechanical treatment.Making use of transmission technique of electron microscopy (TEM) mainly the microstructure and morphology of martensite was analysed,as well as the state of dispersive precipitations of carbides and nitrides resulting from microadditives of such alloys as Nb,V,Ti or B,introduced into the steel.Observations revealed both a fine lathed and twin structure of the matrix of martensite in the investigated steel.By means of the method of electron diffraction particles of secondary strengthening phases of the M(C,N) type of a nanocrystalline size could be identified,and also non-metallic oxide inclusions,affecting the mechanism of strengthening of the investigated steel.
文摘The article describes principles of developing steels for maritime structures and main pipelines.The scientific approach lies in forming an ultra fine-grained and submicrocrystal structure through thermomechanical treatment of low-carbon low-alloyed steels,providing higher strength and resistance to brittle fracture.The article presents results of assessing the operability characteristics and introducing new steels.