• CN:11-2187/TH
  • ISSN:0577-6686

机械工程学报 ›› 2021, Vol. 57 ›› Issue (8): 175-183.doi: 10.3901/JME.2021.08.175

• 材料科学与工程 • 上一篇    下一篇

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304不锈钢板材冲压成形中应变诱发马氏体及其影响

杨钒, 梁君, 杨瑞霞   

  1. 绵阳师范学院机电工程学院 绵阳 621000
  • 收稿日期:2020-04-16 修回日期:2020-10-22 出版日期:2021-04-20 发布日期:2021-06-15
  • 作者简介:杨钒,男,1970年出生,博士,副教授。主要研究方向为不锈钢板材成形性能。E-mail:yfcad@163.com

Strain-induced Martensite and Its Influence in Stamping of 304 Stainless Steel Sheet

YANG Fan, LIANG Jun, YANG Ruixia   

  1. School of Mechanical & Electrical Engineering, Mianyang Teachers' College, Mianyang 621000
  • Received:2020-04-16 Revised:2020-10-22 Online:2021-04-20 Published:2021-06-15

摘要: X射线衍射分析、磁针分析和力学性能及硬度测试等的结果表明,冷轧(固溶处理)状态的304奥氏体不锈钢板材在冷成(变)形过程中产生了应变诱发马氏体(Martensite,M),扩孔、杯突成形时可达35% M,单向拉伸变形不足10% M。另一方面,发现须在一定程度的应变量驱动下冷轧304钢的亚稳态奥氏体(Austenite,A)才能较明显地转变为马氏体,拉伸试验时此门槛值约为20%;对304钢板料扩孔成形的有限元分析表明,在应变约为10%时即可生成22%的马氏体;那些较高硬度地点,即应变诱发马氏体量较多的部位,也正是扩孔应变量最大的区域。分析认为,二向拉应力状态的扩孔、杯突成形更有利于具有体积膨胀效应的A→M转变,能在主要变形区域(凸台、杯突处)诱发多量的马氏体,产生的综合硬化效应可达Δ35 HRB。304钢薄板成形中所诱发的马氏体是甚低碳(wC<0.05%)的体心立方强韧结构(α'-马氏体),具有增加n值、促进变形传播和应变均匀化等作用,有利于不锈钢板料伸长类成形性能的提升以及获得高的扩孔值λ、杯突值IE,也有利于提高304不锈钢冲压制件的结构强度。

关键词: 304奥氏体不锈钢, 应变诱发马氏体, 扩孔成形, 杯突成形, 拉伸变形, 有限元

Abstract: The results of XRD diffraction analysis, magnetic needle analysis, mechanical properties and hardness tests show that the 304 austenitic stainless steel sheet in the cold-rolled (solution treated) condition produces strain-induced martensite(M) during cold forming(deformation) processes, which can reach 35% M for holes expansion and cup protrusion forming, but uni-directional tensile deformation being less than 10% M. On the other hand, it is found that the meta-stable austenite(A) of cold-rolled 304 steel must be driven by a certain degree of strain to be more obviously transformed into martensite. This threshold is about 20% ε during the tension test. The finite element analysis of 304 steel sheet expansion holes forming shows that 22% martensite can be formed at strain of about 10%,those locations with higher hardness, that is, areas with a lot of strain-induced martensite, are also the areas where the expansion holes strain is the largest. The analysis shows that the bi-directional tensile stress state of expansion holes and cupping forming is more conducive to the A→M transformation with volume expansion effect, which can induce a large amount of martensites in the main deformation area (boss, cupping) and the comprehensive hardening effect up to Δ35HRB. The martensite induced in the forming of 304 steel sheet is a very low carbon(wC<0.05%) body-centered cubic tough structure(α'-martensite), which has the effects of increasing n value, promotes deformation propagation, strain homogenization and others, it is conducive to the improvement of the elongation-type forming properties of the stainless steel sheet, the attainment of a high λ value of the expansion holes and the IE value of the cupping,and the promotion of structural strength of 304 stainless steel sheet stamping parts.

Key words: 304 austenitic stainless steel, strain induced martensite, expansion holes forming, cupping forming, tensile deformation, FEM

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