The influence of Ce on the solidification microstructures of M2 high speed steel was studied. The results show that Ce has the effect of alleviating the segregation of alloying elements such as W and Mo in high speed ...The influence of Ce on the solidification microstructures of M2 high speed steel was studied. The results show that Ce has the effect of alleviating the segregation of alloying elements such as W and Mo in high speed steel. With the addition of Ce, the amount of eutectic carbides is decreased and the flakes of the carbides are refined. Ce mainly segregates onto the interface between the eutectic carbide and austenite, and a part of Ce enters M 2C carbide. Ce can also enhance the breaking and spheroidizing of the net work eutectic carbides during high temperature heat treatment.展开更多
High speed steel has been widely used in various fields due to their excellent red hardness and good wear resistance.However,the influence of mischmetal(Ce-La)on the as-cast microstructures and mechanical properties o...High speed steel has been widely used in various fields due to their excellent red hardness and good wear resistance.However,the influence of mischmetal(Ce-La)on the as-cast microstructures and mechanical properties of high speed steel has rarely been reported.Thus,the microstructure and mechanical properties of M2 high speed steel with addition of mischmetal(Ce-La)were investigated.The morphology and distribution of the eutectic carbides of the steel were observed by using optical microscopy and scanning electron microscopy,and the impact toughness and bending strength were tested.The results show that adding mischmetal has an obvious effect on the microstructure and mechanical properties of M2 high speed steel.The coarse eutectic structure is refined,the weak connection of the carbide networks is broken and the flake carbides become short and fine.More networks of eutectic carbides dissolve into the matrix.When a suitable adding content of mischmetal is selected,for example,0.3mass%,the impact strength and bending strength can increase by 27% and 10.76% compared with that without mischmetal,respectively.展开更多
Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2（M2）melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrite...Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2（M2）melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites grow into the melt and then the fine equiaxed cellularstructure appears in upper melt region nearly surface.The substructure of cellular grains anddendrites was observed to consist of martensite and retained austenile,while the carbides asM<sub>6</sub>C<sub>■</sub> Cr<sub>7</sub>C<sub>3</sub> and MC distributed at their boundaries.It is believed that the highermicrohardness up to HV<sub>0.1</sub>=865—960 of the laser fused structure of the alloy is due to the oc-currence of martensite.展开更多
The carbides of high speed steels have a determinant influence on their properties, and the control of the carbides has been a hot topic in development of high speed steels. The decomposition of the coarse primary M2C...The carbides of high speed steels have a determinant influence on their properties, and the control of the carbides has been a hot topic in development of high speed steels. The decomposition of the coarse primary M2C carbide in the as-cast M2 high speed steels with Silicon addition and without Silicon addition was investigated by using optical microscope, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis. Both the M2 high speed steel and the M2-1Si steel were heated at 1000 and 1150 ℃, the soaking time were 15 min, 30 min, 1 h, 2 h and 4 h, respectively. The results showed that the decomposition of M2C carbides to M6C and MC carbides occurred during heating at 1000 ℃,the degree of the decomposition became obvious with the increase of heating time or addition of silicon. After the tested steels were heated at 1000 ℃ for 1 h, the primary M2C carbides in the M2-1Si steel had decomposed into M6C and MC completely, but the decomposition of the primary M2C carbides in the M2 steel was incomplete. Silicon addition was found to accelerate the decomposition of the coarse primary M2C carbides during heating and to inhibit the growth and coarseness of the decomposition products.展开更多
Semi-solid casting of M2 high speed steel ingots was investigated by inclined slope pre-crystallization method. Effects of casting temperature and slope length on the microstructure of M2 HSS ingots were investigated....Semi-solid casting of M2 high speed steel ingots was investigated by inclined slope pre-crystallization method. Effects of casting temperature and slope length on the microstructure of M2 HSS ingots were investigated. M2 cast ingots of non-dendritic primary austenite and fine eutectic ledeburite network carbide structure were obtained, with the casting temperature, slope length and angle of 1480 ℃, 500 mm and 60° respectively. Meanwhile, the microstructure of cast samples was quantitatively assessed by Image tool software. Results show that optimum mean equivalent diameter of primary austenite crystal grain is 50.8 μm, shape factor is 0.83, and mean thickness of network carbide is 5.21 μm.展开更多
M2高速钢是使用最广泛和最具代表性的工具钢。采用电子束选区熔化(selective electron beam melting,SEBM)增材制造技术成形M2高速钢能有效避免传统铸造组织粗大、碳化物偏析等问题,有望大幅改善高速钢力学、磨损等性能。通过使用不同...M2高速钢是使用最广泛和最具代表性的工具钢。采用电子束选区熔化(selective electron beam melting,SEBM)增材制造技术成形M2高速钢能有效避免传统铸造组织粗大、碳化物偏析等问题,有望大幅改善高速钢力学、磨损等性能。通过使用不同扫描参数与2种粉床预热温度在316L不锈钢基板上制备了M2高速钢块体试样,重点研究了扫描参数和粉床预热温度对成形M2高速钢致密度及晶粒尺寸、碳化物等显微组织的影响。在最优化参数下,成形M2高速钢致密度达99.7%,平均晶粒尺寸在3~6μm,碳化物细小且分布较为均匀。通过维氏硬度试验和摩擦磨损试验分析了SEBM成形M2高速钢的硬度与磨损性能。结果表明,在最优化参数下成形的M2高速钢维氏硬度可达1034.2HV_(0.2),远高于商用M2高速钢刀具(815HV_(0.2)~845HV_(0.2)),同时磨损率仅有(3.58±0.36)×10^(-5)mm^(3)·N^(-1)·m^(-1),较回火态锻造母材降低了13.7%。此外,SEBM成形M2高速钢的磨损机制主要为磨粒磨损和粘着磨损。展开更多
文摘The influence of Ce on the solidification microstructures of M2 high speed steel was studied. The results show that Ce has the effect of alleviating the segregation of alloying elements such as W and Mo in high speed steel. With the addition of Ce, the amount of eutectic carbides is decreased and the flakes of the carbides are refined. Ce mainly segregates onto the interface between the eutectic carbide and austenite, and a part of Ce enters M 2C carbide. Ce can also enhance the breaking and spheroidizing of the net work eutectic carbides during high temperature heat treatment.
基金Item Sponsored by Key Project of National Research Program of China(2011BAC10B04)National Natural Science Foundation of China(51201075)
文摘High speed steel has been widely used in various fields due to their excellent red hardness and good wear resistance.However,the influence of mischmetal(Ce-La)on the as-cast microstructures and mechanical properties of high speed steel has rarely been reported.Thus,the microstructure and mechanical properties of M2 high speed steel with addition of mischmetal(Ce-La)were investigated.The morphology and distribution of the eutectic carbides of the steel were observed by using optical microscopy and scanning electron microscopy,and the impact toughness and bending strength were tested.The results show that adding mischmetal has an obvious effect on the microstructure and mechanical properties of M2 high speed steel.The coarse eutectic structure is refined,the weak connection of the carbide networks is broken and the flake carbides become short and fine.More networks of eutectic carbides dissolve into the matrix.When a suitable adding content of mischmetal is selected,for example,0.3mass%,the impact strength and bending strength can increase by 27% and 10.76% compared with that without mischmetal,respectively.
文摘Microstructure of the deepest zone of high speed steel W6Mo5Cr4V2（M2）melt after laser fu-sion was found to be so fine as the ehill zone of a solidified ingot.When narrower chill zoneformed,the long columnar dendrites grow into the melt and then the fine equiaxed cellularstructure appears in upper melt region nearly surface.The substructure of cellular grains anddendrites was observed to consist of martensite and retained austenile,while the carbides asM<sub>6</sub>C<sub>■</sub> Cr<sub>7</sub>C<sub>3</sub> and MC distributed at their boundaries.It is believed that the highermicrohardness up to HV<sub>0.1</sub>=865—960 of the laser fused structure of the alloy is due to the oc-currence of martensite.
基金National Natural Science Foundation of China (50725413)National High-tech R&D Program of China ("863" Program) (2008AA031101)
文摘The carbides of high speed steels have a determinant influence on their properties, and the control of the carbides has been a hot topic in development of high speed steels. The decomposition of the coarse primary M2C carbide in the as-cast M2 high speed steels with Silicon addition and without Silicon addition was investigated by using optical microscope, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis. Both the M2 high speed steel and the M2-1Si steel were heated at 1000 and 1150 ℃, the soaking time were 15 min, 30 min, 1 h, 2 h and 4 h, respectively. The results showed that the decomposition of M2C carbides to M6C and MC carbides occurred during heating at 1000 ℃,the degree of the decomposition became obvious with the increase of heating time or addition of silicon. After the tested steels were heated at 1000 ℃ for 1 h, the primary M2C carbides in the M2-1Si steel had decomposed into M6C and MC completely, but the decomposition of the primary M2C carbides in the M2 steel was incomplete. Silicon addition was found to accelerate the decomposition of the coarse primary M2C carbides during heating and to inhibit the growth and coarseness of the decomposition products.
基金Funded by the Science Foundation of Beijing Jiaotong University (No.230-12)
文摘Semi-solid casting of M2 high speed steel ingots was investigated by inclined slope pre-crystallization method. Effects of casting temperature and slope length on the microstructure of M2 HSS ingots were investigated. M2 cast ingots of non-dendritic primary austenite and fine eutectic ledeburite network carbide structure were obtained, with the casting temperature, slope length and angle of 1480 ℃, 500 mm and 60° respectively. Meanwhile, the microstructure of cast samples was quantitatively assessed by Image tool software. Results show that optimum mean equivalent diameter of primary austenite crystal grain is 50.8 μm, shape factor is 0.83, and mean thickness of network carbide is 5.21 μm.
文摘M2高速钢是使用最广泛和最具代表性的工具钢。采用电子束选区熔化(selective electron beam melting,SEBM)增材制造技术成形M2高速钢能有效避免传统铸造组织粗大、碳化物偏析等问题,有望大幅改善高速钢力学、磨损等性能。通过使用不同扫描参数与2种粉床预热温度在316L不锈钢基板上制备了M2高速钢块体试样,重点研究了扫描参数和粉床预热温度对成形M2高速钢致密度及晶粒尺寸、碳化物等显微组织的影响。在最优化参数下,成形M2高速钢致密度达99.7%,平均晶粒尺寸在3~6μm,碳化物细小且分布较为均匀。通过维氏硬度试验和摩擦磨损试验分析了SEBM成形M2高速钢的硬度与磨损性能。结果表明,在最优化参数下成形的M2高速钢维氏硬度可达1034.2HV_(0.2),远高于商用M2高速钢刀具(815HV_(0.2)~845HV_(0.2)),同时磨损率仅有(3.58±0.36)×10^(-5)mm^(3)·N^(-1)·m^(-1),较回火态锻造母材降低了13.7%。此外,SEBM成形M2高速钢的磨损机制主要为磨粒磨损和粘着磨损。
