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

Abstract

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.

Effect of Heat Treatment on the Phase Composition and Corrosion Resistance of 321 SS Welded Joints Produced by a Defocused Laser Beam

“…Furthermore, when it comes to the advantages of laser and electron beam welding, such as penetration depth and high welding speed, lower specific heat input and thermal distortion, narrow weld and HAZs, high precision, ease of automation, etc. [3,15], then in the case of ASS or DSS welding, this is a controversial issue, since in this case high cooling rates lead to a negative effect on the phase balance of the weld metal and HAZ, and, accordingly, on the mechanical and corrosion properties [16,17,18,19].…”

Corrosion resistance analysis of the weld metal of low-alloy high-strength steel considering different alloy compositions

“…Moreover, the behavior of hydrogen in gray cast iron was similar to that of steel. With the increase of diffusive hydrogen content, critical stress would gradually decrease and the tendency to crack would gradually increase (Yang et al, 2018). Zhang et al studied the relationship between hydrogen and steel tensile strength and concluded that after hydrogen charging, the notch tensile strength of high-strength steel decreased.…”

Effect of corrosion on the fatigue behaviour of butt welds of G20Mn5QT cast steel and Q345D hot rolled steel in 3.5‐wt% NaCl solution

“…Due to the action of corrosion, the fatigue strength of the welded steel components significantly decreased even after a short exposure time (approximately 10 days). Scanning electron microscopy (SEM) can be used to analyze the corrosion fatigue failure mechanism of welded metallic materials 14–18 . According to fracture analyses, pitting corrosion occurs on the surface of welded metallic materials during corrosion fatigue, which is one of the reasons leading to the nucleation of fatigue cracks 19,20 .…”