Si、Mn元素对奥氏体不锈钢微观组织和拉伸性能的影响

为提高奥氏体不锈钢耐蚀性,合金中可同时加入Si、Mn元素,提高合金氧化膜形成能力,同时增加奥氏体基体稳定性,但Si、Mn的添加还能够对合金的冷变形组织和力学性能产生影响。本研究设计了不同硅、锰含量的奥氏体不锈钢,采用SEM、EPMA以及TEM等方法表征合金显微组织形貌,采用室温拉伸分析合金的力学性能。结果表明,Si质量分数由1.0%提高至2.0%,20%冷变形合金组织中变形孪晶体积分数由4.98%增加至8.33%,合金屈服强度由620 MPa提高至682 MPa,延伸率基本保持不变;Mn质量分数由1.5%提高至2.0%,变形孪晶体积分数由8.33%减少至7.22%,屈服强度由682 MPa降低至627 MPa,延伸率由16.0%增加至21.3%;添加Si元素,合金中孪晶数量增加,合金强度提高并保持塑性;添加Mn元素,合金中孪晶数量减少,强度降低塑性增强。

Effect of Si and Mn on Microstructure and Tensile Properties of Austenitic Stainless Steel

Si and Mn are usually added into austenitic stainless steels to improve their corrosion resistance by improving the oxide film forming ability and increasing the stability of austenite matrix. However, the additions of Si and Mn can significantly affect the microstructure and mechanical properties of the cold-worked material. In this study, austenitic stainless steels with different Si and Mn contents are designed. The microstructure of the alloys is characterized by SEM, EPMA, and TEM, and the mechanical properties are evaluated by tensile tests at room temperature. As Si increases from 1.0 wt.% to 2.0 wt.%, the volume fraction of deformation twins increases from 4.98% to 8.33%, the yield strength increases from 620MPa to 682 MPa, and the elongation basically remains constant; as Mn increases from 1.5 wt.% to 2.0 wt.%, the volume fraction of the deformation twins decreases from 8.33% to 7.22%, the yield strength decreases from 682MPa to 627 MPa, and the elongation increases from 16.0% to 21.3 %; Si addition increases the quantity of deformation twins in the alloy, improves the strength of the alloy and maintains plasticity; Mn addition reduces the number of the deformation twins in the alloy, reduces the strength of the alloy and enhances plasticity.