碳钢表面激光熔覆铝青铜涂层的组织及铜渗透现象

Microstructure and Copper Contamination Phenomenon of Laser Cladded Aluminum Bronze Coatings on Carbon Steel Surface

为了提高海洋用钢的表面性能,采用激光熔覆技术在Q235钢板表面熔覆了QAl-7铝青铜合金,并对其组织以及熔合线处的铜渗透现象进行了研究。研究结果表明,铝青铜熔覆层在凝固过程中会发生液相分离以及过饱和脱溶现象,其组织主要由富铜相(Cu_3Al、Cu_9Al_4)以及富铁相(AlFe_3、AlFe)构成。熔池中的铜液沿着基体钢奥氏体晶界润湿扩展,在热影响区形成铜渗透现象。铜渗透深度与熔合区的宽度有关,熔合区越宽,铜渗透越深。通过控制激光熔覆工艺参数减少熔合区的宽度进而控制渗透深度,从而抑制铜渗透裂纹的产生。

The QAl-7 aluminum bronze powder is cladded on the Q235 carbon steel surface by laser cladding technique in order to improve the surface performances of marine steels. Microstructure and copper contamination phenomenon near the fusion line are also studied. The research results show that the aluminum bronze coating undergoes liquid-phase separation and decomposition of oversaturated solid solution. The microstructure mainly consists of copper-rich phase (Cu3Al, Cu9Al4) and iron-rich phase (AlFe3, AlFe). The liquid copper alloy in the molten pool wets and extends along the austenite grain boundary of the substrates. There occurs the copper contamination phenomenon in the heat-affected zone. The contamination depth of copper alloy is related to the width of fusion zone. The fusion zone is wider, the copper contamination is deeper. Thus, the depth of copper contamination can be controlled just via the reduction of the width of fusion zone by controlling laser parameters. The copper contamination cracks are further suppressed.