氩弧重熔对球墨铸铁热浸镀铝层组织和性能的影响

Influence of argon arc remelting on microstructure and properties of hot dip aluminized coating on ductile iron

将球墨铸铁在780℃热浸镀铝后进行氩弧重熔处理,利用扫描电镜和X射线衍射仪对热浸镀铝层和氩弧重熔层组织进行观察,测定了氩弧重熔前后试件截面的显微硬度。结果表明:球墨铸铁热浸镀铝后,镀层由富铝层及扩散层构成,富铝层包含降温形成的针状FeAl3相,扩散层由FeAl3、Fe2Al5相组成,扩散层形状呈柱状延伸到基体中。热浸镀铝层经氩弧重熔处理后,试件由重熔层和过渡层及基体构成。重熔层由Al、Fe、C和FeAl3相组成,过渡层组织为马氏体+残留奥氏体+少量球状石墨。氩弧重熔处理能明显提高热浸镀铝层的显微硬度。重熔层硬度值可达900 HV,在过渡层硬度下降缓慢,直至基体。

The coatings on ductile iron were prepared by hot dip aluminizing and argon arc remelting.Microstructure and microhardness of the coating with and without argon arc remelting was investigated by SEM,XRD and hardness test.The results show that the hot dip aluminized coating consists of aluminum-rich layer and diffusion layer.Acicular FeAl3 phase is observed in the Al-rich layer and the diffusion layer consists of columnar FeAl3 and Fe2Al5 phases extended into the substrate.After argon arc remelting treatment,the hot dip aluminized coating is composed of remelting layer,transition layer and substrate.The main phases are Al,Fe,C and FeAl3 in the remelting layer,microstructure of the transition layer consists of martensite,retained austenite and a little spheroidal-graphite.Argon arc remelting treatment obviously increases microhardness of hot dip aluminized coating.Hardness of the remelted layer reachs 900HV,and hardness declines slowly in the transition layer until substrate.