预拉伸应变强化对S30403奥氏体不锈钢形变马氏体相转变的影响

Effection of Strain-Stretching on Strain Induced Martensite Transformation of S30403 Austenitic Stainless Steel

分别在-196℃和室温下以5×10-4/s(慢速拉伸)、2×10-2/s(快速拉伸)两种应变速率对6.5 mm厚的固溶态S30403轧板进行预拉伸应变强化。用XRD,SEM和TEM研究形变马氏体转变机制及转变量,并研究应变强化后试样的显微硬度。室温下,在变形初期,快速拉伸试样的α'-马氏体相变速度快,含量多于室温下慢速拉伸试样的值,但变形量大于等于15%时,由于变形温升作用,α'-马氏体相变量小于慢速拉伸;-196℃下,快速拉伸试样,变形初期α'-马氏体相含量少,但随着变形量增大,α'-马氏体量迅速增加,在变形量大于6%时,超过室温下快速拉伸变形试样产生的量;ε-马氏体量受预拉伸工艺影响较小,基本保持在7%以下;预拉伸后试样的显微硬度值随预拉伸工艺变化趋势和α'-马氏体的变化规律一致。

Strain - stretching of solution treated S30403 stainless steel sheet samples with 6.5 mm in thickness were performed at - 196 ℃ and room temperature with the strain rates of 5 × 10-4/s （ slow strain rate） ,2 ×10-2/s （fast strain rate）. The mechanism and volume fraction of strain induced martens- ite were investigated by using TEM, SEM and XRD. The microhardness of strain - stretched samples were also investigated. At room temperature, the rate of or＇ -martensite transformation with fast strain rate is faster in the beginning of the specimen deformation, while the amount of or＇ - martensite phase is less than that of elongated samples with slow strain rate when elongation greater than 15% due to the deforma- tion temperature rise effect. With fast strain rate ,the rate of a＇ -martensite transformation is slower in the beginning of the specimen deformation at -196 ℃, while or＇ - martensite phase increased rapidly, the amount was more than that of samples elongating at room temperature when elongation greater than 6%.The ε - martensite is less affected by strain - stretching less;Trends of microhardness value of the elongated sam consistent with the variation of or＇ - martensite. process and pies changed substantially maintained at 7% or with strain- stretching process is