Performance of semiconductor laser welding 85Cr17 and 0Cr18Ni9 stainless steel

by:Caodahai     2021-09-11
High carbon martensitic stainless steel 85Cr17 has high hardness, strength and wear resistance, but due to the high carbon content and relatively low chromium content, its corrosion resistance is lower than other types of stainless steel, this type of steel is often used for high Load and resistant to atmospheric corrosion. Since the brittle and hard martensite structure is formed after welding, its hardening tendency and crack sensitivity are very large, so the weldability is poor. The austenitic stainless steel 0Cr18Ni9 has excellent corrosion resistance and mechanical properties, and good welding performance. In order to give full play to the advantages of the two, they need to be welded together. However, the physical properties and chemical composition of the two types of stainless steels, such as the coefficient of linear expansion and thermal conductivity, are quite different, which makes it difficult to achieve a good connection between them using traditional welding processes. Laser welding has the advantages of high energy density, strong welding penetration, small heat-affected zone, small welding deformation, and fast welding speed. It is especially suitable for welding special and difficult-to-weld of the same or dissimilar metals. It has great advantages in welding production. Application potential. In recent years, the use of high-power lasers for welding has attracted widespread attention at home and abroad.   There are many researches on the welding of low-carbon martensitic stainless steel and austenitic stainless steel at home and abroad, but little research on the butt welding of high-carbon martensitic stainless steel and austenitic stainless steel. In this paper, a semiconductor laser is used as the welding heat source to perform butt welding of different stainless steels on 85Cr17 and 0Cr18Ni9, and the microstructure and properties of the welded joint are analyzed.  Before the experiment, polish the welding surface of the base metal to remove the sundries and oil stains on the surface, and then clean it. The laser adopts the LDF40022000 high-power semiconductor laser with an output wavelength of 900~1030nm, a larger output power of 2000W, butt joints, argon protection, and slow cooling after welding. The laser welding parameters are: welding speed vu003d5mm/s, defocus amount △fu003d-1mm, laser power P are 700, 800 and 900W respectively.  The butt welding of 85Cr17 and 0Cr18Ni9 is realized by semiconductor laser welding process, and the joint is well formed, which meets the requirements of use. The central area of u200bu200bthe weld is mainly equiaxed, the near-central area is a mixed structure of columnar crystals and dendrites, and the edge area of u200bu200bthe weld is columnar crystals. The heat-affected zone on the 0Cr18Ni9 side is narrow, the heat-affected zone on the 85Cr17 side is wider, and the heat-affected zone on the 85Cr17 side is the weak area of u200bu200bthe joint. The microhardness of the welded joint is higher at the junction of the weld and the heat-affected zone on the 85Cr17 side, which is 576HV0.2. The tensile samples are all broken in the heat-affected zone on the 85Cr17 side, which is a dimple fracture. When the weld is not penetrated, the tensile strength of the welded joint reaches 88% of the 0Cr18Ni9 base material, and when the weld is penetrated, the tensile strength reaches 95% of the 0Cr18Ni9 base material. above. (The above is edited by metal laser cutting machine, see http://www.gnlaser.com/?fproducts for details)
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