The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experiment...The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experimental parameters for thermal simulation were optimized, and the thermal simulating experiments were carded out on a Gleeblel500 thermal simulator. The process parameters for the manufacture were optimized after analysis of the data, and the productive experiments were performed after the water box in front of the no-twist blocks was reconstructed, to control the temperature of the loop layer. The results from the productive experiments showed that the cooling rate of 10-15℃/s was reasonable before phase transformation, about 5℃/s during phase transformation, and 600-620℃ was the suitable starting temperature for phase transformation. The ultimate strength of the Ф11.0 mm wire was increased to 1150-1170 MPa with an increase of 20-30 MPa, the percentage reduction of section was to 34%-36% with an increase of 1%-3% by testing the finished products after reconstruction.展开更多
It was shown by the study of TEM that the fine lamellar pearlite becomes a ductile phase dur- ing cold drawing.There exist many ledges to emit dislocations at Fe_3C/Fe interface.It is one of the reasons that high dens...It was shown by the study of TEM that the fine lamellar pearlite becomes a ductile phase dur- ing cold drawing.There exist many ledges to emit dislocations at Fe_3C/Fe interface.It is one of the reasons that high density of dislocations emerges at the Fe_3C/Fe interface. Furthermore,there are some evidences to support that dislocation cuts through Fe_3C.There- fore,it is necessary to consider the contribution of cementite being sheared strengthening.展开更多
Low carbon steel wires were prepared by two processes,serial drawing(SD)and reverse-direction drawing(RD).Effects of the two processes on microstructure and mechanical properties in steel wires were investigated by fi...Low carbon steel wires were prepared by two processes,serial drawing(SD)and reverse-direction drawing(RD).Effects of the two processes on microstructure and mechanical properties in steel wires were investigated by field emissio scanning electron microscopy,electron backscatter diffraction(EBSD),X-ray diffraction and transmission electron microscopy(TEM).Residual compressive stress and more low-angle grain boundaries were introduced into the steel wire by the RD.As a result,the RD wires exhibited a greater tensile strength when drawing strain s<1.18.The SD encouraged grain refinement and texture formation in the wire.The SD wires exhibited a smaller average width of the elongated ferrite grain and a higher intensity of(110)fiber texture at all drawing strains.Therefore,the SD wires showed a bit greater tensile strength and 20%greater torsion performance than the RD wires at c=2.51.TEM and EBSD analysis indicated that dislocation tangle was formed easily in RD wires,and it transformed into twist boundary.This twist boundary impeded the grain refinement in the RD wires,and there were still non-fibrous grains in the RD wires even after heavy drawing.展开更多
The flux cored wires with different rare earth oxide additions for hardfacing the workpieces of medium-high carbon steel were developed. The microstrucmre of the hardfacing layer was observed using the optical microsc...The flux cored wires with different rare earth oxide additions for hardfacing the workpieces of medium-high carbon steel were developed. The microstrucmre of the hardfacing layer was observed using the optical microscopy. The average dimension of primary austenite grains in hardfacing layer was measured by image analyzer. The primary austenite grain growth activation energy and index were calculated according to Sellars＇s mode and Beck formula, respectively. Moreover, the effect of rare earth oxide on the growth dynamics of primary aus- tenite grain was analyzed, and then discussed with the misfit theory. The experimental results showed that, by adding rare earth oxide, the av- erage dimension of primary austenite grains in hardfacing layer of medium-high carbon steel decreased, and it was the smallest when the ad- dition of rare earth oxide was 5.17 wt.%. Meanwhile, at this rare earth oxide addition, the primary austenite grain growth activating energy in hardfacing layer was the largest, while its index was the smallest. The calculated results indicated that the primary austenite grain could be refined because LaAlO3 as heterogeneous nuclei of γ-Fe was the most effective.展开更多
文摘The existing problems in the manufacture of SWRH82B high carbon steel wire were discussed by sampling and testing the microstructure and properties of the steel from the workshop. To solve the problems, the experimental parameters for thermal simulation were optimized, and the thermal simulating experiments were carded out on a Gleeblel500 thermal simulator. The process parameters for the manufacture were optimized after analysis of the data, and the productive experiments were performed after the water box in front of the no-twist blocks was reconstructed, to control the temperature of the loop layer. The results from the productive experiments showed that the cooling rate of 10-15℃/s was reasonable before phase transformation, about 5℃/s during phase transformation, and 600-620℃ was the suitable starting temperature for phase transformation. The ultimate strength of the Ф11.0 mm wire was increased to 1150-1170 MPa with an increase of 20-30 MPa, the percentage reduction of section was to 34%-36% with an increase of 1%-3% by testing the finished products after reconstruction.
文摘It was shown by the study of TEM that the fine lamellar pearlite becomes a ductile phase dur- ing cold drawing.There exist many ledges to emit dislocations at Fe_3C/Fe interface.It is one of the reasons that high density of dislocations emerges at the Fe_3C/Fe interface. Furthermore,there are some evidences to support that dislocation cuts through Fe_3C.There- fore,it is necessary to consider the contribution of cementite being sheared strengthening.
基金This work is supported by the National Natural Science Foundation of China(Grant No.51371050)Special Talent Program of Jiangsu Province(2015-XCL-004)+2 种基金the Industry・University Strategic Research Fund of Jiangsu Province(BY2016076-08)The study is also partly supported by the Science and Technology Advancement Program of Jiangsu Province(Grant No.BA2017112)L.C.Zhou appreciates the support provided by Fundamental Research Funds for the Central Universities and the Scientific Research Foundation of the Graduate School of Southeast University(YBJJ1674).
文摘Low carbon steel wires were prepared by two processes,serial drawing(SD)and reverse-direction drawing(RD).Effects of the two processes on microstructure and mechanical properties in steel wires were investigated by field emissio scanning electron microscopy,electron backscatter diffraction(EBSD),X-ray diffraction and transmission electron microscopy(TEM).Residual compressive stress and more low-angle grain boundaries were introduced into the steel wire by the RD.As a result,the RD wires exhibited a greater tensile strength when drawing strain s<1.18.The SD encouraged grain refinement and texture formation in the wire.The SD wires exhibited a smaller average width of the elongated ferrite grain and a higher intensity of(110)fiber texture at all drawing strains.Therefore,the SD wires showed a bit greater tensile strength and 20%greater torsion performance than the RD wires at c=2.51.TEM and EBSD analysis indicated that dislocation tangle was formed easily in RD wires,and it transformed into twist boundary.This twist boundary impeded the grain refinement in the RD wires,and there were still non-fibrous grains in the RD wires even after heavy drawing.
基金Program supported by National Nature Science Foundation of China(51271163)Key Project of Science and Technology of Hebei Province(09215106D)
文摘The flux cored wires with different rare earth oxide additions for hardfacing the workpieces of medium-high carbon steel were developed. The microstrucmre of the hardfacing layer was observed using the optical microscopy. The average dimension of primary austenite grains in hardfacing layer was measured by image analyzer. The primary austenite grain growth activation energy and index were calculated according to Sellars＇s mode and Beck formula, respectively. Moreover, the effect of rare earth oxide on the growth dynamics of primary aus- tenite grain was analyzed, and then discussed with the misfit theory. The experimental results showed that, by adding rare earth oxide, the av- erage dimension of primary austenite grains in hardfacing layer of medium-high carbon steel decreased, and it was the smallest when the ad- dition of rare earth oxide was 5.17 wt.%. Meanwhile, at this rare earth oxide addition, the primary austenite grain growth activating energy in hardfacing layer was the largest, while its index was the smallest. The calculated results indicated that the primary austenite grain could be refined because LaAlO3 as heterogeneous nuclei of γ-Fe was the most effective.
