Influência do processo de soldagem sobre as propriedades mecânicas de juntas soldadas de tubulações de aço API 5L X60.

Abstract

In structures Offshore and Onshores, the gas and oil transport normally is accomplished by pipelines API 5L X60, X65 e X70. Because of its low coast the Shielded Metal Arc (SMA) welding, process is widely used for transversal welding. In this work the percentile of the different types of weld metal micro constituents originated from differents welding process of the mechanical properties of API 5L X60 pipeline welded joints was evaluated. For this, weld metals specimen obtained by SMA, Flux Cored Arc (FCA) with protection of CO2 and MAG self protected, Gas Metal Arc (GMA) with protection of inert gas (MIG) and active gas welding process, were submitted to impact Charpy in different temperatures to hardness tests and to quantitative metallographic analyses. As filler metals AWS E 7010G and AWS E 7018 for SMA, AWS E 71 T-l for FCA protected with C02 and AWS E 71T1-11 for FCA protected without and AWS ER 70S-6 for SMA were used. The results obtained indicated significant variations in the values of micro hardness and impact resistance of the weld metals obtained by differents welding process, resultant from different percentiles of AF, PF caused by differents percentiles of alloy elements and heat input in each welding process. The higher impact resistance was obtained by process SMA E 7018, MAG with CO2 gas protection and flux cored Arc (FCA), while the weld metal obtained by FCA self protected process, MIG and SMA E 7010G showed the worst results.