Supermartensitic stainless steel deposits: shielding gas and post-weld heat treatment

ZAPPA, SEBASTIAN; SVOBODA, HERNAN; SURIAN, ESTELA

WELDING JOURNAL

Published by American Welding Society

Lugar: Miami; Año: 2013 vol. 92 p. 297 - 303

0043-2296

Welding of supermartensitic stainless steel plays a crucial role in structural components, influencing their toughness and resistance to sulphide stress cracking. Post weld heat treatment adjusts the final properties of the weldments, bearing on microstructural evolution. The objective of this work was to study the effects of different shielding gas mixtures and the post weld heat treatment on supermartensitic stainless steel all-weld metal properties. Three all-weld metal test coupons were prepared according to standard ANSI/AWS A5.22-95, using a 1.2 mm diameter tubular metal-cored wire under Ar-5%He, Ar-2%CO2 and Ar-18%CO2 gas shielding mixtures in the flat position, with a nominal heat input of 1 kJ mm-1. The post weld heat treatment used was 650 ºC during 15 minutes. All-weld metal chemical composition analysis, metallurgical characterization, hardness and tensile property measurements and Charpy-V tests were carried out. It was found that as CO2 increased in the shielding gas C, O and N contents increased, as well as, mechanical properties varied: hardness and ultimate tensile strength increased and toughness decreased. The post weld heat treatment improved toughness. Technological property of the consumable was also studied.