Corrosion Behavior of 316L and Alloy 182 Dissimilar Weld Joint with Post-Weld Heat Treatment

Abstract

Austenitic stainless steel and nickel-base alloys welds are widely used in nuclear reactor components, plants of energy generation, chemical, and petrochemical industries, due to their high corrosion resistance. The post weld heat treatments (PWHT) are generally applied to welding in order to relieve the welding residual stress. The aim of this work was to evaluate the influence of different PWHT on corrosion behavior of a dissimilar weld joint of two AISI 316L austenitic stainless steel plates with a nickel-base alloy as filler material in saline environments. The material was submitted to heat treatments for three hours at 600, 700 and 800 °C. The weld joint was examined by optical microscopy to determine the effects of PWHT in the microstructure. The corrosion behavior of the samples before and after heat treatment was evaluated using cyclic potentiodynamic polarization (CPP) in sodium chloride solutions (19% v/v) and pH 4.0 at room temperature. Metallographic analyses showed that delta ferrite dissolute as PWHT temperature increased. CPP curves demonstrated an increase of pitting corrosion resistance as the PWHT temperature rises, although the pit size has been increased. The heat treated weld joint at 600 °C showed a similar corrosion resistance compared to as-welded material.

Stress Corrosion Cracking Threshold for Dissimilar Capacitive Discharge Welding Joint with Varied Surface Geometry

“…From the SCC's point of view, the resulted dissimilar metal joint is more susceptible to the SCC. Recently, it has been suggested that post-welding heat treatment could improve the resilience of dissimilar metal welding joints to the SCC load [10].…”

Studies on corrosion behavior of AISI 316L cold metal transfer weldments in physiological solutions

“…44 The dissolution of higher d-ferrite can increase the pitting tendency and acts as a favorable spot for the initiation of pits. 45 As the OCP has been held steady, a small difference in the I corr (0.83 mA/cm 2 ) between WM and BM may be less damaging to the formation of localized galvanic cell. The HAZ corrosion resistance was comparatively lower and the corrosion resistance followed the trend (WM > BM > HAZ).…”