Effect of Heat Input on the Stress Corrosion Cracking Behavior of Weld Metal of Nitrogen-Added AISI Type 316 Stainless Steel

Abstract

Abstract Round tensile specimens of AISI Type 316N (UNS S31651) stainless steel weld metal, made by manual metal arc welding (MMAW) process using heat inputs ranging from 3.07 kJ/cm to 7.41 kJ/cm, were subjected to stress corrosion cracking (SCC) tests in boiling acidified sodium chloride (NaCl) solution (initial stress level = 250 MPa) and in boiling 45% magnesium chloride (MgCl2) solution (initial stress level = 120 MPa), using the constant load technique. In boiling acidified NaCl tests, the open-circuit potential (vs saturated calomel electrode [SCE]) was monitored with respect to time to determine the critical cracking potential (CCP) at the time-of-failure. In boiling acidified NaCl solution, the SCC time-to-failure (tf) increased while the CCP decreased with increasing heat input. In boiling 45% MgCl2 solution, no significant change in tf was observed. The tf in acidified NaCl solution was far greater than that in 45% MgCl2 solution. Failure occurred by a combination of transgranular stress corrosi...