Weldability of Duplex stainless steel clad plate

Duplex stainless steel clad plate (thickness of coating ≤ 0.5mm) is the latest thin-layer stainless steel clad plate, solve its welding process, so that the welded joint can achieve the same or similar corrosion resistance as the cladding, for Duplex The application and promotion of thin stainless steel clad plate is of great significance. We first analyze the influence of welding process on the corrosion performance of SUS316 austenitic stainless steel welded joints. (TIG+M) and micro-beam plasma arc welding (0.25+3+0.25) mm Duplex stainless steel clad plate, analysis of the distribution of alloy elements, microstructure and corrosion resistance of welded joints under various welding process conditions Changes in performance and mechanical properties.

Analysis of corrosion performance of welded joints of TIG, MIG and TIG+M welded SUS316 stainless steel plates shows that: TIG+M and MIG welded joints have good intergranular corrosion resistance, TIG welded joints have poor intergranular corrosion resistance, and their intergranular corrosion resistance The order of size is: base metal>TIG+M>MIG>TIG; under the three welding methods, the order of corrosion resistance of welded joints in 9.8% sulfuric acid solution is: base metal>TIG+M>MIG>TIG; at 5 % hydrochloric acid solution: base metal>TIG>TIG+M>MIG.
Comparing the properties of welded joints of laser-welded Duplex stainless steel composite plates shows that: when laser welding ultra-thin stainless steel clad plates, the heat-affected zone and weld seam of the welded joints are small in size and well formed, and the mechanical properties of the welded joints are excellent, but the base carbon steel is The dilution rate of cladding alloy elements is relatively large, the Cr content in the weld zone is 6% to 7%, and the Ni content is 2% to 3.5%, which cannot meet the composition requirements of corrosion resistance, and the corrosion resistance of the weld surface is poor.
The results of welding Duplex stainless steel clad plates with the TIG+M method of multi-layer multi-pass welding show that: the welding of Duplex stainless steel clad plates adopts single-sided groove and double-sided groove, welding current 105A ~ 110A, voltage 20 ~ 22V, welding speed 2.1 ~ 2.5mm/s, the welded joint is well formed, the Cr content of the weld metal surface reaches 15 ~ 17%, the Ni content reaches 6 ~ 7%, and the corrosion resistance of the weld surface is good; Mechanical property comparison, single-sided welding, double-sided welding and filler plus welding wire welding methods, the joint tensile strength is better than the base metal, the fracture of the MIG welded joint occurs in the fusion zone, and the joint tensile strength is lower than the base metal.
The results of cladding ultra-thin stainless steel clad plate with micro-beam plasma arc show that: 25A plasma arc current can melt through the thickness of the stainless steel cladding at one time, and can melt to the depth of about 150 μm of the base carbon steel, and the chemical composition of the joint is the same as that of the cladding The content of Cr and Ni in the layer stainless steel is close, which provides the possibility for the welding process of stainless steel clad plate by micro-beam plasma arc welding.