Abstract
In the present work, dissimilar butt joints between a low-Ni, medium-Mn austenitic stainless steel, M-Mn SS, and a Ni-Cr austenitic stainless steel, Ni-Cr SS, were processed by utilizing the gas tungsten arc welding (GTAW) technique at different heat inputs. A filler metal of ER308 was employed in the welding process. The filler yields 480 MPa, which is equivalent to the yield strength of M-Mn SS. The microstructural analysis and mechanical performance (i.e., tensile strength and hardness properties) of the concerned joints were studied by using an optical microscope and uniaxial tensile tests, respectively. The results revealed that a duplex structure from austenite matrix and delta ferrite is promoted in the fusion zone (FZ) of the dissimilar joints processed with low and high energy inputs (0.486 kJ/mm and 0.558 kJ/mm). The FZ of the specimens welded at high heat input exhibited the lowest hardness value (151.2 HV) in comparison to heat affected zone (HAZ) (166.3 HV). Moreover, the joints exhibited a low tensile strength of 610 MPa. The achieved strength is significantly lower than the strengths of the base metals (BMs) M-Mn SS and Ni-Cr SS. This is mainly attributed to the inhomogeneous dendritic structure of the FZ with Cr-carbides precipitation.
Highlights
Austenitic stainless steels (ASSs) are widely used in many industrial applications such as automotive, chemical, petrochemical, marine structure, steel structure, and furniture industries [1]
Cr-Mn stainless steels are developed under a new grade of austenitic stainless steels called the 200 series, reducing Ni content to less than 1 wt.% to meet market needs with higher quality and lower cost compared to the ASSs 300 series [4,6]
These results can be attributed to the high content of delta ferrite in the weld metal at the low heat input
Summary
Austenitic stainless steels (ASSs) are widely used in many industrial applications such as automotive, chemical, petrochemical, marine structure, steel structure, and furniture industries [1]. The typical chemical composition of ASSs 300 series contains 18–26 wt.% Cr and 8–37 wt.% Ni, in addition to low C content ranges (0.03–0.25 wt.%) [3]. Ni is responsible for stabilizing the austenitic microstructure at room temperature; it increases the cost of alloy. Cr-Mn stainless steels are developed under a new grade of austenitic stainless steels called the 200 series, reducing Ni content to less than 1 wt.% to meet market needs with higher quality and lower cost compared to the ASSs 300 series [4,6]. Cr-Mn SS (200 series) naturally possesses lower corrosion resistance compared to Cr-Ni SS (300 series) due to the low content of Cr and Ni
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