奥氏体量及预应变量对0.1C-4.98Mn中锰钢力学性能的影响

采用610℃5h炉冷和800℃20 min水淬+625℃12 h空冷两种热处理工艺和0～20%拉伸预应变等试验方法,分析了 6.9%和13.6%两种奥氏体量及0～20%预应变量对中锰钢5 mm板力学性能变化的影响。利用XRD试验法测量奥氏体的体积分数,拉伸试验法测量力学性能。研究结果表明:在同一预应变量下,奥氏体体积分数为13.6%的试样与6.9%的试样相比,屈服强度低约30 MPa、抗拉强度高约40 MPa、屈强比小约0.1、总延伸率约大7个百分点、加工硬化效果更明显等。而在同一奥氏体量水平下,随预应变量增大,屈服强度、抗拉强度和屈强比都提高、总伸长率下降;且随真应变增大,加工硬化行为可分为四个阶段:减小(Ⅰ阶段)、增大(Ⅱ阶段)、几乎不变(Ⅲ阶段)、减小(Ⅳ阶段)。

Effect of Austenite Volume and Pre-Strain on Mechanical Properties of 0.1C-4.98Mn Medium Manganese Steel

The change influence of 6.9% and 13.6% two austenite contents and 0 ~ 20% pre-strain process on mechanical properties of medium manganese steel 5 mm plate is analyzed by the test method of 610℃ 5 h furnace cooling and 800℃ 20 min W. C. +625 ℃ 12 h A. C. two heat treatment and 0 ~20% pre-strain process. The amount of retained austenite in the steel is determined by X-ray diffraction analysis and its mechanical properties are measured by tensile test. Research results show that at the same pre-strain level,compared to the sample with 6.9% austenite volume fraction,the sample with 13.6% austenite volume fraction has lower yield strength by about 30 MPa,higher tensile strength about 40 MPa,lower yield strength ratio by about 0.1,higher total elongation by about 7 percentage point,and more obvious work hardening behavior. At the same austenite content,with the increasing of pre-strain,the yield strength,tensile strength and yield-strength ratio increase,the total elongation decreases. With the increasing of true strain,the work hardening behavior can be divided into four stages:decreasing (stage I) increasing (stage II) ,almost unchanged (stage III) and decreasing (stage IV).