激光扫描速度对Co基合金堆焊重熔层组织和硬度的影响

研究了激光功率为2.5kW时,三种不同扫描速度(2mm.s-1、4mm.s-1、8mm.s-1)对重熔的Co基合金堆焊层熔宽、熔深、搭接宽度、枝晶尺寸以及显微硬度分布的影响。试验结果表明,堆焊层经激光重熔后,随着扫描速度的提高,重熔层熔宽和熔深、搭接宽度、枝晶尺寸均随之减小,组织较原始堆焊层明显细化,硬度明显提高。然而,当扫描速度为8mm.s-1时,搭接宽度为零,出现未重熔塔接部分,使得堆焊重熔层表面硬度出现较大波动。

Effect of Laser Scanning Speed on Microstructure and Hardness of Remelted Co-based Alloy Layer

Effect of different laser scanning speeds(2mm.s-1,4mm.s-1,8mm.s-1) on width and depth of remelted pool,overlap width,dendrite size and microhardness of the remelted Co-based alloy hardfaced layer has been studied when the laser power was 2.5kw.The results revealed that width and depth of remelted pool,overlap width and dendrite size decreased all with the increase of the scanning speed,and that microstructure of the remelted hardfaced layer is finer than that of unremelted hardfaced layer,what is more,the microhardness was obviously enhanced.Hoewer,the width of overlap become zero,namely unremelted area occurred,while the scanning speed was increased to 8mm.s-1.As a result,surface hardness of the remelted hardfaced layer fluctuated obviously.