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Hot Tensile Properties of Autogenous Pulsed Current Gas Tungsten Arc Welded Super 304HCu Austenitic Stainless Steel Joints


Affiliations
1 Dept. of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu, India
2 Center for Materials Joining and Research (CEMAJOR), Dept. of Manufacturing Engg., Annamalai University, Annamalai Nagar, Tamil Nadu, India
3 Naval Material Research Laboratory (NMRL), Ambernath, Mumbai, India
     

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The super 304HCu austenitic stainless steel tubes containing 2.3 to 3 (% wt) of Cu is mainly used in superheaters and reheater of ultra super critical boilers. The addition of Cu to super 304HCu has caused improvement in its corrosion and creep resistance. Austenitic stainless steels welded by constant current gas tungsten arc welding (GTAW) produce coarse columnar grains, increase alloy segregation and may result in low mechanical properties of the weld joint. Hence, autogenous pulsed current GTAW (PC-GTAW) was used to weld super 304HCu tubes of 57.1 mm outer diameter and 3.5 mm thick to control the solidification structure by altering the prevailing thermal gradients in the weld pool. The microstructure, hot tensile properties (550 °C, 600 °C and 650 °C), and fracture surface of the autogenous PC-GTAW welded joint was evaluated. Current pulsing in PC-GTAW joint cannot eliminate segregation in weld metal and exhibited lower tensile strength than the parent metal at all test temperature.

Keywords

Super 304HCu Stainless Steel, Autogenous Pulsed Current Gas Tungsten Arc Welding, Hot Tensile Properties, Microstructure.
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  • Hot Tensile Properties of Autogenous Pulsed Current Gas Tungsten Arc Welded Super 304HCu Austenitic Stainless Steel Joints

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Authors

M. Vinoth Kumar
Dept. of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu, India
V. Balasubramanian
Center for Materials Joining and Research (CEMAJOR), Dept. of Manufacturing Engg., Annamalai University, Annamalai Nagar, Tamil Nadu, India
A. Gourav Rao
Naval Material Research Laboratory (NMRL), Ambernath, Mumbai, India

Abstract


The super 304HCu austenitic stainless steel tubes containing 2.3 to 3 (% wt) of Cu is mainly used in superheaters and reheater of ultra super critical boilers. The addition of Cu to super 304HCu has caused improvement in its corrosion and creep resistance. Austenitic stainless steels welded by constant current gas tungsten arc welding (GTAW) produce coarse columnar grains, increase alloy segregation and may result in low mechanical properties of the weld joint. Hence, autogenous pulsed current GTAW (PC-GTAW) was used to weld super 304HCu tubes of 57.1 mm outer diameter and 3.5 mm thick to control the solidification structure by altering the prevailing thermal gradients in the weld pool. The microstructure, hot tensile properties (550 °C, 600 °C and 650 °C), and fracture surface of the autogenous PC-GTAW welded joint was evaluated. Current pulsing in PC-GTAW joint cannot eliminate segregation in weld metal and exhibited lower tensile strength than the parent metal at all test temperature.

Keywords


Super 304HCu Stainless Steel, Autogenous Pulsed Current Gas Tungsten Arc Welding, Hot Tensile Properties, Microstructure.