Cr对低碳Si-Mn系TRIP钢组织与力学性能的影响

Effect of Cr on Microstructure and Mechanical Properties of Low Carbon Si-Mn TRIP Steel

主要研究了Cr对低碳Si-Mn系TRIP钢组织与力学性能的影响。首先利用Formastor-F型膨胀仪测定了含Cr和不含Cr两种低碳钢的连续冷却转变(CCT)曲线,分析指出了Cr对连续退火工艺的潜在影响;然后采用Gleeble-3800热/力模拟试验机对两种钢的薄板试样进行了连续退火模拟实验,并通过拉伸试验测定了力学性能;最后采用金相、扫描电镜、X-射线衍射分析等技术考察分析了两种钢的显微组织。结果表明:含Cr的TRIP钢的组织比较细小,铁素体晶粒近似等轴分布;两种TRIP钢的残余奥氏体含量相近,但含Cr钢的残余奥氏体中的含碳量较高。分析认为这是由于含Cr钢在热轧阶段较易生成细小的组织,而在热处理阶段则抑制贝氏体的生成,最终获得稳定的残余奥氏体。

The effects of Cr on microstructure and mechanical properties of low carbon Si-Mn transformation induced plasticity （TRIP） steel were studied. First, the dynamic CCT curves of two kinds of steel （with and without Cr） were determined by a Formastor-F dilatometer, and the potential impact of Cr on continuous annealing process was analyzed; Secondly,the continuous annealing simulation experiments of the two kinds of steel were done on a Gleeble-3800 simulator, and the mechanical properties were tested on static tensile tester. Lastly, the microstructure of these two kinds of steel was examined and analyzed by metallogragh, SEM, X-ray diffraction tester and so on. The results show that the grain of containing Cr steel is smaller than the other, and its ferrite structure is mainly composed of equiaxed grain, the carbon content in residual austenite is higher, too. It is concluded that the containing Cr steel is relatively easily formed into fine grain structure in hot rolling process, and more stable residual austenite is obtained finally in heat treatment process because of the suppression of Cr on the bainite transformation.