Modeling of Corrosion Fatigue Life of Stainless Steel Joints Welded by Laser-Metal Active Gas Hybrid Welding

The mechanical properties and corrosion resistance of the stainless steel (SS) corbel decline sharply after the welding process, which may cause serious accidents. Combining with microcharacteristics, mechanical properties, and corrosion properties, mathematic theories were used and an accurate prediction model of the corrosion fatigue life of SS butt joints produced by laser-metal active gas hybrid welding (LMHW) was established. The joints produced by LMHW have good mechanical properties, with the joint strength coefficient a remarkable 89%. In corrosion fatigue testing, corrosion pits will first appear in the weld seam as a result of the microstructural difference, then cracks initiate. Meanwhile, both the higher NaCl concentration and lower stress ratio will promote the anodic dissolution of metal, leading to the reduction and obscuring of fatigue striation features on the fracture surface. This high-accuracy mathematical modeling can help validate the advanced LMHW method and, in turn, facilitates the manufacture of stainless steel corbels in rail vehicles.