钻头轴颈用钢热处理组织性能及渗碳数值模拟

Heat treated microstrucures and properties of bit journal steel and numerical simulation of carburization

通过钢表面渗碳及热处理分析渗层的组织及性能,用Matlab软件模拟渗层碳浓度梯度,预测渗碳对硬化层深度的影响。结果表明:钢表层获得回火隐针马氏体+大量碳化物组织的硬化层。当碳传递系数β、碳扩散常数D0、碳浓度影响系数Bc分别取1.16×10^(-4)mm/s、25 mm^(2)/s和0.6时,模拟与试验结果接近。预测得出,在1.0%、1.1%、1.2%、1.3%碳势下,分别渗碳26.947、13.028、8.389、6.009 h,热处理后获得深度为0.3 mm的硬化层。

Microstructure and properties of carburized layer of tested steel were analyzed by carburizing and heat treating tests.The concentration gradient of carburized layer was numerically simulated using Matlab software,and then the influence of carburizing process on hardened layer depth was predicated. The results show that harden layer composed of tempered cryptoneedle martensite and a large number of carbides form on the surface of tested steel. The simulation results agree well with the test results when the selected carbon transfer coefficient β,carbon diffusivity D0 and influence constant of carbon concentration Bc are 1.16×10^(-4) mm/s,25 mm^(2)/s and 0.6 respectively. The predicted results show that the hardened layer with depth 0.3 mm form after heat treatment,provided the needed carburizing time for with carbon potential 1.0%,1.1%,1.2% and1.3% are 26.947 h,13.028 h,8.389 h and 6.009 h respectively.