铜/钢MIG复合增材制造组织及性能研究

Study on microstructure and properties of copper/steel MIG filler composite additive manufacturing

利用MIG复合增材制造方法在20 mm厚低碳钢上交替熔覆硅青铜与304不锈钢制备复合增材制造熔覆层,对3种不同增材制造路径制备的熔覆层成形质量进行了研究,揭示了不同熔覆层显微组织特点和硬度分布。研究结果表明,铜和钢熔覆层熔合线处均形成了良好的冶金结合,铜熔覆层会产生气孔,钢熔覆层中会形成铜向钢的渗透裂纹,铜层会向钢熔覆层塌陷。在铜熔覆层,钢会渗入铜中形成固溶体,该区域显微组织表现为球形的铁基固溶体弥散分布在铜基固溶体中;在钢熔覆层,底部钢呈细小的柱状晶沿垂直熔合线方向生长,并向顶部慢慢长大,当钢层作为最顶层熔覆层时,会形成等轴晶。铜熔覆层硬度在90~175 HV左右,随着进入铜层的钢含量增多而增大。304不锈钢熔覆层硬度在160~526 HV左右,而在钢熔覆层中临近铜熔覆层区域,由于Si元素的渗入,硬度会显著提高。

In this paper,the composite cladding layer of silicon bronze and 304 stainless steel were built on the 20 mm thickness low carbon steel surface by MIG arc additive manufacturing technology.The forming quality of cladding layers under three different arc additive manufacturing paths was studied.The microstructure and microhardness distribution of different cladding layers were revealed.The results showed that good metallurgical bonding was formed at the fusion line of copper and steel cladding,the porosity was produced in the copper cladding,the copper to steel penetrating crack was formed in the steel cladding,and the copper cladding collapsed to the steel cladding.In the copper cladding,steel penetrated into copper to form solid solution.The microstructure in this area was characterized by spherical iron-based solid solution dispersed in copper-based solid solution.In the steel cladding,fine columnar crystals grew along the direction vertical to fusion line and slowly grew to the top.When the steel cladding was the top cladding,equiaxed crystals will be formed.The microhardness of copper cladding was about 90-175 HV,which increased with the increase of steel content in copper cladding.The microhardness of 304 steel cladding was about 160-526 HV,while in the steel cladding,near the copper cladding area,the microhardness increased significantly improved due to the infiltration of Si element.