Mechanical Properties of Dissimilar Welds between AISI 4130 and GOST09ch16N4B

Mechanical properties of dissimilar weld joints between GOST09ch16N4B (a martensitic stainless steel) and AISI 4130 thin sheets made by gas tungsten arc welding (GTAW) were studied using ER410NiMo and ER100S-G filler metals in post weld heat treated conditions. Heat treatment cycles consisted of austenitization at 900, 950 and 1000 °C for 1 h and this was followed by oil cooling and tempering at 400 and 500 °C for 1 h. Tensile tests and microhardness measurements were carried out to evaluate the mechanical properties. The base metals, heat affected zones (HAZs) and fusion zones were observed by optical microscope and scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS). Based on the results, it was found that the joints strength and microhardness profiles were almost independent of austenitization temperature, but they were affected by the tempering temperature. Increasing the tempering temperature led to the reduction in the hardness of AISI 4130 and the joints strength. Tensile samples were fractured in the base metals. Furthermore, the fracture was shifted from GOST09ch16N4B to AISI 4130 with increasing the tempering temperature. Crack initiation from delta-ferrite led to the fracture in GOST09ch16N4B. Strength and elongation obtained from different PWHTs indicated that tempering at 400 °C resulted in acceptable tensile properties for the weldments made with both filler metals.