激光沉积修复DZ125组织与摩擦磨损性能

Microstructure and wear Properties of Laser Deposition Repaired DZ125 Alloy

摘要:

在DZ125铸造基体上进行激光沉积修复实验，研究了激光沉积修复显微组织、硬度及摩擦磨损性能。结果表明：沉积区底部为宽度约8μm的平面晶、沿沉积高度方向外延生长排列紧密的柱状晶、中部为树枝晶、顶部为杂乱无章的等轴晶；沉积区层与层交界处γ"相尺寸大于层内，晶界处γ"相尺寸大于晶内；γ+γ"共晶相和MC碳化物沿晶界分布现象明显，沉积区中下部多为短棒状MC碳化物，沉积区顶部多现小块状以及八面体状MC碳化物。基体显微硬度为410～420HV0.3，沉积区显微硬度高于基体，为455～475 HV0.3。沉积区磨损机理主要是轻微的磨粒磨损，耐磨性能优于基体。

Abstract:

A laser deposition repair experiments were carried out on DZ125 casting substrate. The microstructure, hardness and friction and wear properties of laser deposition were studied. The results show that the morphology of the deposition area from bottom to top is as follows:Planar crystals with a width of about 8μm and columnar crystals with close arrangement along the deposition direction are grown. The dendrites in the middle of the sedimentary zone and the chaotic equiaxed crystals at the top. The size of γ "phase at the boundary of the deposit zone is larger than that of the layer, and the size of the γ" phase at the grain boundary is larger than that of the crystal, the phenomenon of the distribution of the eutectic and the mc carbides along the grain boundary is obvious, Different morphologies of MC carbides were found in the deposited area.Most of the MC carbides in the middle and lower parts of the deposit area are short rod-like MC carbides, and the top of the deposit areas are mostly small blocks and octahedral MC carbides.The microhardness of the deposited area is about 455～475 HV0.3, which is higher than that of the substrate 410～420HV0.3.The wear resistance of the deposition area is superior to that of the matrix, and the wear mechanism is mainly abrasive wear .