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将有磁试样与无磁试样进行合金成分对比,用金相显微镜、扫描电镜、透射电镜及X射线衍射仪对两种试样的显微组织、局部化学成分、物相组成等进行了分析,研究304奥氏体不锈钢冷拔过程中出现局部磁性的形成机理。结果表明,有磁试样化学成分中的Mn含量偏高而Ni含量偏低。冷拔过程中有磁试样的显微组织横向与纵向晶粒尺寸均小于无磁试样。有磁试样夹杂物中存在O、Al元素,且氧化物夹杂对局部磁性无影响。有磁试样的物相中α’-bcc马氏体的体积分数比无磁试样高7.98%。304奥氏体不锈钢的合金成分异常,造成奥氏体处于亚稳态;冷拔过程中晶格变形作用和位错增值引起马氏体相变,在材料中形成的应力集中使得马氏体转变量增大,当马氏体相含量超过临界值,出现局部磁性。
Magnetic samples and non-magnetic samples were alloy composition comparison, the use of metallographic microscope, scanning electron microscopy, transmission electron microscopy and X-ray diffraction on the two samples of the microstructure, the local chemical composition, phase composition were The formation mechanism of local magnetism in 304 austenitic stainless steel during cold drawing was analyzed and studied. The results show that the chemical composition of the magnetic sample has high Mn content and low Ni content. During cold drawing, the microstructures of magnetic samples in both transverse and longitudinal directions were smaller than that of non-magnetic samples. There are O, Al elements in the magnetic sample inclusions, and the oxide inclusions have no effect on the local magnetism. The volume fraction of α’-bcc martensite in the phase of the magnetic sample is 7.98% higher than that of the non-magnetic sample. 304 austenitic stainless steel alloy composition anomalies, resulting in austenite in the metastable state; cold drawing process lattice deformation and dislocation value caused by martensite phase transformation, the stress concentration in the material so that the martensite transformation When the content of martensite exceeds the critical value, local magnetism appears.