Abstract
The X70 steel is a material that has a good relation between mechanical strength and toughness, being very used in conduction and transport of oil and gas. With the objective to evaluate the weldability, the microstructural and mechanical characteristics were evaluated along the cross section of joints obtained by GTAW (root) and GMAW (filling) processes of API 5L X70QS seamless steel pipes. The pipe segments machined in J bevel, welded with circumferential rotation to maintain flat welding position with three different heat inputs. Test specimens for tensile tests, Vickers hardness, Charpy impact and chemical analysis, besides metallographic characterization was made for base material and welded joints. The grade X70QS obtained and welded with different heat inputs showed excellent mechanical behavior and particularly low HAZ hardness.
Key-words:
seamless pipe; steel API 5L X70QS; GMAW; GTAW; heat imput