Influence of Preheat and Post Welding Heat Treatment on the Microstructure and Mechanical Properties of High Strength Steel Weld Metal for Application in Mooring Components
Joel Lemos Dias Monteiro1; Amilton Lins de Sousa Junior1; Jorge Carlos Ferreira Jorge1; Luís Felipe Guimarães de Souza1; Ivaní de Souza Bott2
1 Centro Federal de Educação Tecnológica Celso Suckow da Fonseca, PEMM-DIPPG, Rio de Janeiro, Brazil; 2 Pontifícia Universidade Católica do Rio de Janeiro, DEMa, Rio de Janeiro, Brasil
doi:10.20906/CPS/COB-2015-0289
Resumo
The present work is part of a research program for the development of welding procedures for components of mooring systems of oil platforms. In the specific case of the work in subject, the effect of varying the cooling rate of a high strength steel weld metal deposited by GMAW process is discussed for obtaining high mechanical strength and impact toughness, of the order of 860 MPa and 50 joules at -20°C, respectively. Welded joints by GMAW process were prepared, using preheats of 150, 200 and 250°C. After welding, tensile, impact Charpy-V and hardness tests and metallographic examination by scanning electron microscopy were performed in specimens removed integrally from the weld metal, both in as welded and heat treated conditions. The post weld heat treatment (PWHT) was conducted at 600ºC for 1 hour. The results show that it is necessary to control the cooling rate to achieve the requirements of IACS W22 R4 Grade steel, mainly due to the reduction of ultimate tensile strength after post welding heat treatment, which is mandatory for this application.
Palavras-chave: weld metal; mechanical properties; preheat; post weld heat treatment