Caracterização metalúrgica e tenacidade de revestimentos em aços inoxidáveis 317L aplicados por soldagens MIG manual e robotizado para equipamentos do setor de petróleo e gás.

Abstract

The aim of study was to evaluate the microstructural features and toughness of the AISI 317L weld overlay deposited onto ASTM A516 Gr 60 steel substrates. The weld overlays were carried out using the RTW-GMAW (Robotic Twin Wire Gas Metal Arc Welding) and CWM-GMAW (Manual GMAW with addition of cool wire) processes. For both welding processes, it was employed the AWS E317L wire as filler metal. During weldings - using the RTW-GMAW process - two welding heat input were employed (1170kJ/m e 1530kJ/m), and an interpass temperature of 423K. For the CWM-GMAW process, the weldings were carried out using two cool wire speed (Sew), SCw=25x10~3m/s e SCw=40x10~3m/s. From coupons weld overlaid, specimens were obtained and submitted to microstructure and microhardness analysis, and Charpy impact tests at room temperature and 273K. The results showed an increase in dilution and heataffected zone (HAZ) width when the heat input increased. Furthermore, it was presented a methodology to determine - via microhardness - the quantity of HZ in a WM/substrate interface. It was noted that the quantity of HZ was larger for the higher heat input levels. It also was verified that the RTW-GMAW process yielded weld overlays more uniform, less welding faults, shorter HAZ width and higher impact toughness, as compared with the CWM-GMAW process.