Effect of groove shapes on mechanical properties of welded joints of ASTM4130 steel

The 30 mm thick ASTM4130 steel pipe was fabricated by gas tungsten arc welding and shielded metal arc welding under quenched and tempered conditions.Whereafter,the mechanical properties of welded joints of both V groove and combination double.V groove were measured,while the microstructure feature and fracture morphology of both welded joints were investigated.Moreover,the effect of groove shapes on the properties of welded joints was explored.The results show that the welding efficiency of the combination double V groove joint is as two times as that of the V groove joint.But the hardness and toughness of the heat-affected zone（HAZ） with combination double V groove can not satisfy the requirements.Also,the coarse grain heat-affected zone（CGHAZ） of the cap layer is mainly composed of granular bainite,tempered martensite and a small amount of carbon-free bainite,and the fractured surface of the fusion line is entirely dominated by the quasi-cleavage mode.That the mechanical properties of the combination double V groove are lower than that of the V groove lie in the penetration ratio,welding heat input,and the areas and distribution feature of brittle zones.The combination double V groove is not suitable for the fabricating of ASTM4130 steel.