预热温度对U75V激光熔覆成形性能的影响

Influence of preheating temperature on U75V laser cladding forming performance

研究了预热温度对U75V激光熔覆成形的影响,分析了熔覆层显微组织特征和硬度分布。结果表明,当预热温度低于125℃时,熔覆层出现了孔洞和熔深分布不均匀的缺陷,整体尺寸波动较大;125℃预热成形的多层熔覆层无明显缺陷。在母材预热后,单层熔覆层熔覆区组织由魏氏组织变化为下贝氏体,热影响区主要为粗晶马氏体,硬度变化较小。多层熔覆层熔覆区组织为柱状晶和等轴晶共存,热影响区的马氏体分布在熔合线附近区域。预热后熔覆层的硬度有所下降,预热对马氏体转变的影响较小。

The effect of preheating temperature on U75V laser cladding forming was studied,and the microstructure and hardness distribution of the cladding layer were analyzed.The results showed that when the preheating temperature was lower than 125℃,the cladding layer appeared the defects of holes and uneven distribution of penetration depth,and the overall size fluctuated greatly.The multilayer cladding layer preheated at 125℃had no obvious defects.After the base material was preheated,the microstructure of the cladding zone in the single-layer cladding layer changed from Widmanstatten to lower bainite,and the heat-affected zone was mainly coarse-grained martensite with little change in hardness.The microstructure of the cladding zone in the multilayer cladding layer was columnar crystals and equiaxed crystals,and the martensite in the heat-affected zone distributed in the area near the fusion line.The hardness of the cladding layer decreased after preheating,and the preheating had little effect on the martensite transformation.