化学成分对亚稳态奥氏体不锈钢车体板材均匀变形及加工硬化行为的影响

基于化学成分对奥氏体不锈钢稳定性和层错能的影响,通过对2 mm厚的冷轧、退火态的304不锈钢板材试样及2种不同标准的301LN不锈钢板材试样在应变速率为3×10~(-4)/s的拉伸实验和应变诱导α′-马氏体转变量的分析测定,研究化学成分对奥氏体不锈钢应变诱导α′-马氏体相变及均匀塑性变形和加工硬化行为的影响,分析冷轧对稳定性和层错能不同的奥氏体不锈钢变形行为的影响.结果表明:随镍当量、层错能和稳定性的增加,拉伸过程中的应变诱导α′-马氏体转变开始的应变量增大,转变速度降低,转变量减小;两种化学成分不同、强度等级相同的301LN冷轧不锈钢板材试样的变形行为差异很大,冷轧预变形对其拉伸过程力学行为的影响也很大,304板材试样的亚稳态奥氏体不锈钢变形特征只在后期有所体现,但由于马氏体转变量少,流变应力相对较低.所得结论为制造不锈钢轻量车体选材和优化塑性成型工艺提供基础数据.

Influence of Chemical Compositions on Uniform Deformation and Work Hardening Behaviors of Metastable Austenite Stainless Steel Car Body Plates

On the basis of the dependence of stability and stacking fault energy on the chemical compositions of austenite stainless steel,the tensile tests of the 2 mm thick stainless steel 304 sheet sample and two different-standard 301LN stainless steel plate samples all cold-rolled and annealed were made at the strain rates of 3×10~(-4)/s. Volume fractions of strain induced α'-martensite were measured to investigate the effects of chemical compositions on α'-martensite transformation,uniform deformation and work hardening behaviors of austenite stainless steel. Effects of cold rolling on the deformation behaviors of austenite stainless steel with different stability and stacking fault energy were analyzed. The results show as follows: With the increasing of the nickel equivalent,stacking fault energy and stability,the strain increases in the beginning,and then the speed of change reduces,and the amount of change decreases in the tensile progress of strain-induced α'-martensite transformation.Deformation behaviors of the two cold-rolled 301LN samples with different chemical compositions and same strength grade differ a great deal,cold-rolled pre-strain has great impact on the tensile deformation behavior; deformation characteristics of the 304 metastable austenite stainless steel sample are reflected in the later stage of cold-rolling,the flow stress is relatively low due to less martensite transformed. The results provide the basic data for selection of materials and optimization of plastic forming technology in manufacturing light stainless steel car body vehicles.