爆炸加载下AISI304不锈钢板表面硬化和数值模拟

目的 提高AISI304不锈钢板表面硬度。方法 利用爆炸加载表面硬化方法对3 mm厚的AISI304不锈钢板进行了表面硬化处理，通过HXD-1000YM型显微硬度计和JEM-2010型透射电子显微镜对爆炸加载处理后试样的不同部位横截面进行了硬度测量和微观组织表征。采用大型有限元数值模拟软件ANSYS/LS-DYNA对爆炸加载表面硬化过程进行了数值模拟，计算了撞击面平均压力和速度。通过对比数值模拟结果与理论计算结果，分析了特征点碰撞压力和速度对爆炸加载处理后表面硬度的影响。结果 数值模拟结果表明，撞击面压力平均值为5.5 GPa，撞击面平均速度达到了178 m/s，撞击面压力和速度的理论计算值与数值模拟值误差不超过5%。试验结果与数值模拟结果具有一致性。爆炸加载后，试样近起爆端和爆轰末端的撞击压力和撞击速度小于稳定爆轰阶段，导致前者表面硬度小于后者。横截面硬度分布表明撞击表面硬度大于炸药接触面硬度，撞击表面硬度值从210HV提高至450HV，炸药接触面硬度值从210HV提高至390HV。结论 爆炸表面硬化过程中存在边界效应。爆炸表面硬化方法能够显著提高板材表面硬度，同时可以提高板材整体硬度，且硬度提高与变形带和位错阵列形成有关。

Surface Hardening and Numerical Simulation on AISI304 Stainless Steel Plates by Explosive Impact Treatment

The work aims to improve the surface hardness of AISI304 stainless steel plate. Surface hardening treatment was carried out on 3 mm thick AISI304 stainless steel plate by explosive surface hardening technique. The microhardness and the microstructures of the cross sections at the different locations in the treated samples were measured and characterized by HXD-1000YM Micro-hardness tester and JEM-2010 transmission electron microscopy. Numerical simulation was carried out on process of explosive surface hardening by finite element software ANSYS/LS-DYNA. The average pressure and velocity of im-pact surface were calculated. The effect of the impact pressure and velocity on surface microhardness of treated samples at the specific points was analyzed by comparison of the numerical simulation results and the experiment results. From the numerical results, the average pressure at impact point was approximately 5.5 GPa and the average velocity at impact point reached 178 m/s. Error between the theoretical calculation and the numerical calculation of pressure and velocity on impact surface was less than 5%. Experimental results agreed with the numerical simulation results. The impact pressure and velocity near initiation and detonation ends after explosive hardening were less than that at the stage of stabilization detonations. Therefore, microhardness in the former is less than that in the latter. Distribution of hardness on the cross sections indicated that the microhardness of the impact surface was larger than that of the explosive surface and increased from 210HV to 450HV and the microhardness on the explosive surface increased from 210HV to 390HV. There exists the boundary effect in the explosive hardening process. Explosive impact treatment can enhance the surface hardness and entire hardness of plate remarkably. Improvement of surface hardness is related to formation of deformation bands and planar dislocation arrays.