S. Paulraj, National institute of technology, trichirappalli, India; A. S., INDIAN INSTITUTE OF TECHNOLOGY DELHI, NEW DELHI, India; S. R, N. H. A, NITT, TRICHIRAPPALLI, India
Duplex Stainless Steel (DSS) is having the higher mechanical strength and better corrosion resistance than other steels. DSS is commonly used for marine construction, petrochemical and chemical industries. DSS (2205) is having equal amount of α and γ phases. However, the solidification microstructure of the fusion zone in the weld does not have nearly equal amount of α phase and γ phase as that of parent metal. Thus the mechanical properties and corrosion resistance of the DSS welds is degraded. Standard 2205 (UNS S31803) DSS sheets of 5 mm thickness, which is having 22.4% Cr and 6.2% Ni were used in this study. Weld beads were produced with zeron-100 super duplex stainless steel filler wire of higher alloy content (26% Cr and 8% Ni). The different shielding gas and mixtures such as Ar, He and Ar+ 5% N2 were employed in this work. The arc energy was maintained less than 1 kJ/mm. The interpass temperatures were kept as 1000 C.
The pitting resistance equivalent and ferrite number in the weld metal for all the shielding gas and mixtures were investigated. The pitting corrosion resistance tests were carried out as per the ASTM G 46 standard. The mechanical properties of joints such as impact strength and hardness were evaluated. Microstructure evaluation was carried out with the different shielding gases. The effect of fatigue strength of DSS welds with different shielding gases was also studied. Results are discussed in detail.
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