Microstructure and Properties of 20G/316L Dissimilar Metal TLP Welded Joints

The amorphous Ni foil used as the intermediate layer, the 20 steel/316L dissimilar metal was connected by double temperature transient liquid phase diffusion (TLP) welding to obtain a good metallurgical joint. By metallographic microscope (OM), Scanning electron microscope (SEM), energy disperse spectrometer (EDS), X-ray diffraction (XRD) and universal testing machines, the interface formation, elemental diffusion and mechanical properties of joints at different welding temperature were studied. The results show that when the welding temperature is 1080°C, there are large holes in the joint, and the holes gradually disappear with the increase of the welding temperature. Ni elements in intermediate layer and 316L both participate in the formation of the diffusion and dissolution layer I and II, while Cr elements do not participate in the formation of the diffusion and dissolution layer I. The hardness at the center of the middle layer is basically the same as that of 316L, but with the increase of welding temperature, the hardness at the center decreases, and the anti-shear strength increases.