Microstructure And Mechanical Properties Of 316L Stainless Steel Fabricated By Welding Rapid Forming

Welding rapid forming technology, as one of rapid forming technologies, can manufacture metal parts with high density and high properties. Compared with other rapid forming technologies for metal parts, it has obvious advantages on improving manufacturing efficiency and saving cost. Forming path, forming parameters and interpass temperature have important influences on temperature field of deposited metal parts, and effect the formation and transformation of microstructures, which would lead deposited metal parts with diffident properties. In this paper, based on robert GMAW welding technology, 316 L welding wire was used to prepare stainless steel components with arc deposition manufacturing method. The effect of overlap rate, ideal interlaminar height, forming path and interpass temperature on prepared components was investigated. As follows are the main research results:(1) The surface of overlaying layers was flattened as the increase of overlap rate, and an overlap rate of 40% is suitable for 316 L stainless steel arc deposition manufacturing. The model for interlaminar height calculating which is related to the weld width, weld height and weld fusion rate was proposed. With the interlaminar height calculated by the model, thin-wall and inclined thin-wall components that possess of good appearance quality can be achieved by arc deposition manufactured method. For inclined thin-wall parts, while the angle between deposited part’s center line and substrate surface is less then 60°, can’t ensure deposited process going well.(2) The solidification mode of 316 L stainless steel prepared by arc deposition manufactured method was FA mode. On the top-most and bottom-most, solidification mode changed to AF mode due to a higher cooling rate. Orientational and epitaxial growth microstructures observed in deposited components were associated with heat flow. In remelted area, microstructures growth from fusion line point to molten pool; in non-remelted area, microstructures growth upward.(3) Microstructures of the samples deposited with line-shaped path, strip δ-ferrites distributed in austenite matrix. Skeletal δ-ferrites were observed in the samples deposited with cross-shaped path, compared to skeletal ferrites in bow-shaped path deposited samples, their transverse spacing were bigger and their growth direction were changed. As the increasing of interpass temperature, ferrites content were changed. Ferrites total content by 12% at 50℃ interpass temperature up to 16% at 150℃ interpass temperature.(4) Microhardness of arc deposition manufactured 316 L stainless steel samples declined with the increase of deposition height. Tensile strength on the transverse direction is higher than that on the longitudinal direction. Samples deposited by line-shaped path owned the hightest average tensile strength of 519 MPa. Interpass temperature during 50℃ to 100℃, tensile strength is higher while the interpass temperature is lower.