功率对激光热处理ZA35合金组织和性能的影响

Effect of power on microstructure and properties of ZA35 alloy treated by laser heat treatment

用RC-LCD-1500-D-443-N激光熔覆工作站研究了功率对激光热处理ZA35合金组织、硬度和电化学性能的影响。结果表明：激光功率为850 W时,激光热处理ZA35合金枝晶的方向性减弱,晶粒细小,一次枝晶臂和二次枝晶臂尖端圆整,二次枝晶臂间距和腐蚀电流密度分别为15.26μm、1.087μA/cm2,与未激光热处理ZA35合金相比分别减小61.4%和62.6%,表面硬度增加22.5%。适宜激光功率850 W处理后的ZA35合金耐蚀性能增强的主要原因是合金的容抗弧半径增加,极化电阻增大,电极双电层电容下降,腐蚀驱动力降低。

The effect of laser power on the microstructure,hardness and electrochemical property of laser heat treated ZA35 alloy,treated by a RC-LCD-1500-D-443-N laser cladding workstation,was investigated. The results show that when the laser power is 850 W,the dendrite directionality of the alloy decreases and the grains are refined,the primary and the secondary dendrite arm tips are rounded off,the secondary dendrite arm spacing and the corrosion current density are 15. 26 μm and 1. 087 μA/cm2,or 61. 4% and 62. 6% less than that of cast ZA35 alloy respectively,the surface hardness is 22. 5% higher than that of as-cast ZA35 alloy. The main reason of the enhanced corrosion resistance of the ZA35 alloy heat treated with a proper laser power of 850 W is attributed to the increase of the arc radius of the alloy and the polarization resistance,significant decrease of both the electrode double layer capacitor and the corrosion driving force.