H13钢激光填丝仿生耦合热疲劳性能分析

热疲劳龟裂是铝合金压铸模具的主要失效模式. 针对这一现象，利用激光表面熔凝技术及激光表面填丝技术耦合仿生强化模型对压铸模具表面进行强化，分析不同处理方式下热疲劳裂纹扩展形态，探索提高压铸模具寿命的方法. 试验利用Nd:YAG激光器对试样进行加工，每隔500次热疲劳循环后，观察不同试样裂纹扩展情况，5 000次循环后得出裂纹扩展形貌. 结果表明，经过激光表面填丝技术处理所得的仿生单元体硬度相对于激光表面熔凝处理所得单元体略有提高，经激光表面填丝技术处理的试样具有更高的抗热疲劳性能.

Investigation on thermal fatigue property of H13 steel with biomimetic units processed by laser welding with filler wire

Thermal fatigue crack is the main failure mode of aluminum alloy die-casting dies. According to the phenomenon, an attempt to harden the working surface of die-casting dies with biomimetic units was made by using biomimetic coupled laser welding with filler wire process and laser remelting process, respectively. The propagation of thermal fatigue crack was analysed under different treatments. The ways to improve die service life was explored. The samples of this experiment was processed by Nd:YAG laser.The thermal fatigue cracks were measured or observed at intervals of 500 cycles and the morphology of thermal fatigue cracks was obtained after 5 000 cycles. The experimental results show that the microhardness of biomimetic units that was made by laser welding with filler wire is slightly above the biomimetic units that was made by laser remelting process, samples that is processed by laser welding with filler wire have better thermal fatigue resistance ability.