硬脆钢50SiMnVB激光预控裂纹工艺试验研究

Research on Laser Crack-precontrolling Technology for 50SiMnVB

为改善传统裂解槽加工效率低、后续加工困难等问题,采用高功率CO2激光器对硬脆钢50SiMnVB进行激光预控裂纹工艺试验。采用金相显微镜、扫描电镜以及显微硬度测试仪等设备,对激光深熔区的微观组织形貌、裂纹断口形貌以及显微硬度分布进行了测试分析。利用数值模拟软件SYSWELD对50SiMnVB钢激光深熔处理过程的温度场和应力场分布进行模拟分析。结果表明:由于深熔过程受温度梯度和应力梯度的影响,深熔区产生淬硬脆化裂纹;其开裂机理为深熔区底部出现气孔和微裂纹,裂纹再沿中心向上扩展形成宏观裂纹;经工艺试验与模拟仿真对比后得出最优工艺参数范围,即激光功率为3. 0 kW,扫描速度范围为1. 0～4. 5 m/min,所对应的预制裂纹深度范围约为3～7 mm.

The cracks in 50SiMnVB steel are experimentally controlled by using high power CO 2 laser to improve the processing efficiency and subsequent processing of fracture splitting groove.The laser deeper melting zone of micro-structure,fracture morphology and micro-hardness distribution are analyzed by means of metallographic microscope,scanning electron microscope and micro-hardness tester,respectively.The numerical simulation software SYSWELD is used to simulate the distributions of temperature field and stress field in 50SiMnVB steel during laser deeper melting.The results show that the hardened brittle cracks are generated in the deeper melting zone due to temperature and stress gradient.The cracking mechanism is that the pores and micro-cracks arise at the bottom of the deeper melting zone,and the cracks expand along the center to form the macroscopic cracks.The optimal range of processing parameters is obtained by the experiment and simulation with laser power of 3.0 kW,and scanning speed of 1.0-4.5 m/min.The corresponding depth range of prefabricated crack is about 3-7 mm.