Mechanical and Microstructural Characterization of TIG Welded Dissimilar Joints between 304L Austenitic Stainless Steel and Incoloy 800HT Nickel Alloy

Abstract

In this article, the mechanical properties and microstructure of 304L austenitic stainless steel/Incoloy 800HT nickel alloy dissimilar welded joints are investigated. The joints were made of 21.3 mm × 7.47 mm tubes using the TIG process with the use of S Ni 6082 nickel filler metal. No welding imperfections were found and high strength properties of joints were obtained, meeting the assumed acceptance criteria of the product’s standards. The tensile strength of the welded joints was higher than for the joined materials (Incoloy 800HT). Macro- and microscopic metallographic tests revealed the correct morphology of the joints and the appropriate structures in their critical zones. However, differences were found in the morphologies of the zones between the weld and the base materials. In fusion boundary from the side of the Incoloy 800HT alloy, no clear outline of the fusion line was observed (type A fusion boundary), while increased grain size and an epitaxial structure were observed. In turn, in the zone: weld–304L steel, a distinct fusion line was observed with areas with an increased amount of high-temperature δ ferrite (type B fusion boundary). No precipitates were found that could reduce the resistance of the joints to intergranular corrosion. A hardness decrease (approximately 30 HV0.1) in the transition zone: austenitic steel–weld and an increase of hardness (approximately 10 HV0.1) on the opposite side of the welded joint were observed.

Laser Dissimilar Welding of AISI 430F and AISI 304 Stainless Steels

“…Pankaj et al [ 20 ] investigated the possibility of laser welding of AISI 304 steel with low carbon steel and found a correlation between heat input and the properties of the joints. Rogalski et al [ 21 ] welded 304L steel with Incoloy 800HT and conducted an analysis of the properties and structure of the joint, confirming that the TIG method can be used to join these materials even with an unfavorable design resulting from the working conditions of the joint. On the other hand, Pańcikiewicz et al [ 22 ] indicated in their work that although austenitic steels are treated as easily weldable, they cannot be ignored and potentially dangerous imperfections should be identified using both traditional and new test methods.…”

Dissimilar underwater wet welding of HSLA steels

“…The weldability of steels in the air environment is widely investigated. It has been shown that it depends on chemical composition, manufacturing method, and technological, metallurgical, and construction factors, and above all the welding technology [15][16][17]. Much less frequently mentioned is the subject of steels with yield strength higher than 420 MPa welded directly in the water.…”

Microstructure and Mechanical Properties of Fe-36Ni and 304L Dissimilar Alloy Lap Joints by Pulsed Gas Tungsten Arc Welding

“…For the heat-affected zone in the 304L side, the microhardness tends to increase with increasing distance from the center of the weld and reached up to a maximum hardness of 164 HV1. Rogalski et al [ 34 ], studied the mechanical and microstructural of Incoloy 800 HT and austenitic stainless steel 304L dissimilar joints manufactured by gas tungsten arc welding, it is found that the hardness of the HAZ near 304L decreases, which results from the structure transform to δ ferrite. However, Shakil M. et al [ 7 ], studied the welding of 690 alloy and 304L dissimilar alloys via electron beam welded, it is found there doesn’t exist hardness decreases.…”