Fabrication of mild steel/high-strength steel composite structure by double wire twin electrode gas tungsten arc additive manufacturing

The mild steel/high-strength steel composite structure can reduce the amount of alloying elements on the premise of ensuring the bearing capacity, and reduce the cost. An efficient and stable method of double wire twin electrode gas tungsten arc additive manufacturing was proposed in this paper. The mild steel wire H08Mn2Si and the high strength steel wire H06MnNi3CrMoA were fed into the molten pool together at the deposition current of 400 A. The composition gradient regulating research of deposited metal was conducted. The results showed that the deposition rate is 2.4 kg/h. The designed composition of the deposited metal can be accurately achieved by adjusting the ratio of wire feed speeds. The tensile strength, yield strength, and micro hardness of the deposited metal increased linearly with the increase of the high-strength steel mass fraction. The ranges of them are 565-914 , 441-803 MPa and 206-327 HV respectively. Finally, a sliding bearing with mild steel/high-strength steel composited structure was designed and the additive manufacturing of it was realized using the proposed method. The component gradient transition zone was deposited between the bearing matrix and the bearing bush to reduce the hardness gradient in the forming part. The bimetallic interface mismatch problem was alleviated.