高硬度激光熔覆专用Fe基合金强韧化机理

The mechanism of strengthening and toughening of crack-free Fe-based alloy with high hardness for laser cladding

为解决高硬度激光熔覆层容易产生裂纹的问题,采用自制激光熔覆专用铁基合金粉末,在未采用预热和后热等措施的情况下,获得了高硬度且无裂纹的熔覆层。揭示了激光熔覆专用铁基合金强韧化机理,即晶内主要为中碳混合马氏体和晶间有相当数量残余奥氏体的复相组织强化。中碳混合马氏体作为基体,为熔覆层提供了高的硬度和强度以及一定的韧性。塑韧性极好的少量残余奥氏体则分布于晶界附近,在不明显降低熔覆层硬度和强度的同时吸收和减小熔覆层应力,降低开裂敏感性。

Crack-free laser-cladding layers with high hardness were obtained by using self-made Fe-based alloy powders for laser cladding without preheating and tempering.This paper revealed the mechanism of strengthening and toughening of the developed Fe-based alloy.The mixed martensite with medium carbon content contributes high hardness and high strength,as well as somewhat toughness;the retained austenite,which is distributed along grain boundaries,contributes excellent plasticity and toughness.The retained austenite can absorb and reduce the stress of the layers,and decrease the cracking susceptibility while it will not obviously decrease the hardness and strength of the cladding layers.