Probing the stress corrosion cracking resistance of laser beam welded AISI 316LN austenitic stainless steel

Abstract

The stress corrosion cracking (SCC) resistance of the laser beam welded (LBW) AISI 316LN austenitic stainless steel (SS) was assessed and compared to the base metal (BM). The weld joint was produced using a 2.5 kW laser power source at 1500 mm/min welding speed. Microstructural characterization of the base metal and weld joint were done by the following techniques: (i) Optical Microscopy (OM), (ii) Scanning Electron Microscopy (SEM) and (iii) Transmission Electron Microscopy (TEM). The primary mechanical properties such as strength, toughness and hardness of the welded joint were evaluated and compared with the base metal. Stress Corrosion Cracking (SCC) assessment was done in boiling 45 wt% MgCl2 solution at constant load condition as per American Society for Testing and Materials (ASTM) standard G36-94. From the SCC experiment data, steady-state elongation rate ([Formula: see text]), transition time ([Formula: see text]) and time to failure ([Formula: see text]) were found and generalized equations to predict the time to failure of the base metal and LBW joint were successfully derived. The passive film rupture mechanism majorly influenced the SCC failure for 316LN and welded joint. The formation of the discontinuous δ-ferrite network, residual stress and nitrogen pore nucleation at the fusion zone of the LBW joint deteriorated the SCC resistance. The metallographic and fractographic studies revealed brittle transgranular SCC failure of the base metal as well as the LBW joint in all the stress conditions.

Corrosion resistance and metallurgical behaviour of CMT welded Al-LCS dissimilar butt joint exposed in simulated industrial environment

“…18 Recently, numerous researchers studied the corrosion properties of weldments fabricated by various process. [19][20][21][22] Based on the comprehensive literature survey, it is realized that there is a deficiency of systematic research to investigate the corrosion behaviour of dissimilar joints. In the present work, AA 6061 aluminium alloy (3 mm) with low carbon steel dissimilar butt joints were fabricated using CMT welding to improve the corrosion resistance and mechanical properties.…”