Abstract
Dissimilar welding is a unique and complex process because in each zone in the different welding area have unique structures and characteristics. The modified structure may have a significant effect on weld metal properties. In this research, the primary objective is to investigate the microstructure evolution and hardness distribution mode of a different joint HY80 steel plate and Duplex type 2205 welded by using thick weld or shielded metal arc weld (SMAW). The microstructure of weld metal zones was observed. The test plates were welded in both butt joint and fillet joint by using E309L filler metal. It was found that the 309L electrode provides the equilibrium between austenite and ferrite phase in the different weld metal zones of DSS 2205 and HY80 steel joint. The results show that hardness distribution of different joint of both butt weld and fillet weld presents sinusoidal trend, where hardness in HAZ is highest. The peak value of hardness appeared in HY 80 base metal near the fusion line. The microstructure of base metal DSS 2205 shows fine grains of ferrite and austenite grains with dark and light shades respectively. The microstructure of weld metal shows coarse grains of austenite along with some slag inclusions as dark spots. The Heat Affected Zone of HY80 steel plate shows coarse grains of austenite and ferrite, while the heat affected zone of DSS 2205 shows thin fusion line with coarse grains of ferrite as dark zones and coarse grains of austenite as light zones. There is, a degree of variation in weld metal ferrite content was observed. Keywords: Duplex Stainless Steel, HY80, SMAW, Dissimilar Joint, Hardness, and Impact Toughness.
Highlights
The HY-80 steel is fine-grained structural steel that designed to achieve a high yield strength that can resist the permanent plastic deformation
Due to the rapid cooling rate caused by thermal cycle from the welding process, the carbon migration can cross the fusion boundary of the HY80 steel plate into the weld metal
Diffusion of carbon from base metal to the weld metal due to the rapid cooling rate caused by thermal cycle from the welding process, the carbon migration can cross the fusion boundary of the HY80 steel plate into the weld metal
Summary
The HY-80 steel is fine-grained structural steel that designed to achieve a high yield strength that can resist the permanent plastic deformation. This steels were used in marine industries, of pressure hulls for the submarine and recently used in maritime industries. The microstructure formed in the welding process is related to the thermal cycle and the alloying elements composition of the base material. The microstructure that is created will vary in weld pool, heat affected zone, fusion line, and base materials. The microstructure weld metal will determine the mechanical properties of the welding results
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