激光退火对Inconel718微观组织和硬度的影响

Effects of Laser Annealing on Microstructures and Hardness of Inconel 718

研究激光退火对Inconel 718 时效合金的显微组织和硬度的影响。一台2.5 kW 的CO2激光机被用来照射试样的表面。在激光能作用下,试样表面层被加热后空冷。通过控制激光工艺参数,在表面不发生熔化的前提下,能够使一定厚度表面层内的硬度降低到标准退火合金的水平,而不影响试样内部母材的硬度。显微组织观察显示表面层的基体强化相(γ"和γ′) 在激光照射过程中被固溶,而其它二次相没有变化。γ"和γ′的固溶被确定是表面层硬度下降的原因。在其它试验条件不变时,确立了退火层生成时由激光散焦距离和扫描速度描述的工艺参数范围。

It was studied annealing on the microstructures and hardness of aged Inconel 718. A 2.5 kW CO2 laser was employed to irradiate the samples surface. Surface layers were heated to high temperatures by laser energy, and then air-cooled. By controlling laser process parameters, hardness in a surface layer can be decreased to that of the standard annealed alloy without surface melting. Microstructures studies suggest that the matrix-strengthening phases (gamma' and gamma') in the surface layer were dissolved by laser irradiation. No changes were observed about other secondary phases. The changes of the precipitation states of these precipitates are proposed as the origination of the hardness decrease. Applicable process parameter ranges defined by defocusing distances and scanning velocities of the laser were established under the same experimental conditions.