W18Cr4V刀具钢脉冲激光Ni60A熔覆层耐磨和耐冲击性能分析

Wear Resistance and Impact Resistance of W18Cr4V Tool Steel Ni60A Cladding by Pulsed Laser

为了提高W18Cr4V刀具钢的使用性能,在其表面制备Ni60A激光熔覆层,对比了不同脉冲激光频率下Ni基涂层析出相及其对耐磨和冲击性能产生的作用。研究结果表明:逐渐提高脉冲频率后,涂层内形成更粗大的初生枝晶,共晶区持续减小。脉冲频率为80 Hz时,得到的等轴晶尺寸基本一致,共晶区中颗粒数量则明显降低。提高脉冲频率后,涂层硬度呈现持续降低,制得了更大磨损率涂层,形成了更少的犁沟,而宽度则持续增加,发生了更大程度的剥落和黏着磨损。提高脉冲频率后,冲击韧性先上升再下降,当脉冲频率为80 Hz时,涂层达到了最优耐冲击效果。脉冲激光作用下发现涂层小断面尺寸跟晶粒尺寸相近,可以推断涂层发生了沿晶断裂,形成了更少的应力集中点。

To improve the performance of W18 Cr4 V tool steel, Ni60 A layer was obtained by laser cladding on its surface. The precipitates of Ni-based coating prepared at different pulse laser frequencies and their effects on wear resistance and impact were compared. Results show that coarser primary dendrites are formed and the eutectic zone is decreasing with increase of pulse frequency. When the pulse frequency is 80 Hz, the equiaxed crystal obtained basically shows the same size, and the number of particles in eutectic zone decreases obviously. When the pulse frequency is increased, the hardness of the coating continues to decrease, which results in higher wear rate. Moreover, furrows become fewer while the wear width continues to increase, and spalling and adhesion wear occur greatly. The impact toughness firstly increases and then decreases with rise of pulse frequency. The coating achieves the optimal impact resistance when the pulse frequency reaches 80 Hz. Under the action of pulsed laser, it is found that the small section size is similar to the grain size. It is inferred that the intergranular fracture appears with fewer stress concentration points.