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The sensitization behavior of the welding heat affected zone (HAZ) in austenitic stainless steels (SSs) was investigated through simulated thermal cycles emulating actual multi-pass welding processes using the Gleeble simulator. The tests were performed with austenitic SSs, considering carbon contents, heat input, and distance from the fusion line to determine the thermal cycle conditions of the HAZ. Higher carbon content led to increased sensitization (degree of sensitization, DOS) values, while the influence of the thermal cycle in the final weld pass was that even though it was rapidly heated to over 1000 °C and cooled at a rapid rate, the DOS value decreased due to partial carbide dissolution and chromium diffusion. Therefore, effective management of the final thermal cycle in the HAZ contributes to improved intergranular stress corrosion cracking resistance. Even with prolonged exposure of the HAZ to the sensitization region, the discovery that corrosion resistance improves when the final heating cycle reaches 1000 °C underscores the importance of HAZ heat cycle management and provides valuable insights for materials engineering and industrial applications. [ABSTRACT FROM AUTHOR]

To investigate corrosion characteristics of gas-tungsten arc welded 304L-ER308L and 316L-ER316L for dry storage canister application, electrochemical impedance spectroscopy, potentiodynamic electropolarization and double loop-electrochemical potentiokinetic reactivation techniques are exploited in 0.6 M NaCl and 0.5 M H2SO4 + 0.01 M KSCN + x M NaCl solution. Microstructure analysis gave that they had dendritic ferrite in austenite matrix mainly in weld metal, and ferrite fraction of 304L-ER308L was much higher than that of 316L-ER316L due to chemical composition effects. In 0.6 M NaCl, pitting corrosion appeared in both base metal and weld for 304L-ER308L because 304L and ER308L had similar electrochemical properties. In case of 316L-ER316L, noble characteristics of 316L induced reduction of corrosion rate in 316L-ER316L but galvanic coupling between base metal and weld induced severe pitting corrosion in base metal. In the H2SO4 solution, three corrosion mechanism appeared for 304L-ER308L: galvanic corrosion in ferrite–austenite; galvanic corrosion in weld-base metal; pitting corrosion in base metal when 0.6 M NaCl was added. For 316L, localized galvanic corrosion in weld-base metal only appeared. [ABSTRACT FROM AUTHOR]

Hydrogen-induced cracking (HIC) susceptibility of the coarse-grained heat-affected zone (CGHAZ) of carbon steel was evaluated using implant tests and the characteristics of susceptible microstructure to HIC was investigated. Three types of carbon steel with different alloying elements were employed as base metals to vary the microstructure of the CGHAZ and implant test assemblies were prepared using an automatic shielded metal arc welding process. A clear difference in microstructure was observed between the CGHAZs of steel with high and low HIC susceptibility; the formation of the primary ferrite in the CGHAZ of carbon steel plays an important role in decreasing the HIC susceptibility. [ABSTRACT FROM AUTHOR]