THE ROLE OF SHIELDING GAS ON MECHANICAL, METALLURGICAL AND CORROSION PROPERTIES OF CORTEN STEEL WELDED JOINTS OF RAILWAY COACHES USING GMAW
Byju John 1  
,   Sathiya Paulraj 2  
,   Jolly Mathew 3  
 
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1
Centre for Excellence in Corrosion and Surface Engineering (CECASE), National Institute of Technology, Tiruchirappalli 620 015, Tamilnadu, India
2
CECASE & Department of Production Engineering, National Institute of Technology, Tiruchirappalli 620 015, Tamilnadu, India
3
Central Workshops, Southern Railway, Tiruchirappalli 620 004, Tamilnadu, India
CORRESPONDING AUTHOR
Sathiya Paulraj   

Department of Production Engineering, National Institute of Technology, Tiruchirappalli 620 015, Tamilnadu, India
Publication date: 2016-12-01
 
Adv. Sci. Technol. Res. J. 2016; 10(32):156–168
 
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ABSTRACT
This analysis lays emphasis on finding a suitable combination of shielding gas for welding underframe members such as sole bar of Railway Coaches made of corten steel; for improved mechanical, metallurgical and corrosion properties of welds using copper coated solid MIG/MAG welding filler wire size 1.2 mm conforming to AWS/SFA 5.18 ER 70 S in Semi-automatic GMAW process. Solid filler wire is preferred by welders due to less fumes, practically no slag and easy manipulation of welding torch with smooth wire flow during corrosion repair attention, when compared to Flux cored wire. Three joints using Gas metal arc welding (GMAW) with shielding gases viz., Pure CO2, (80% Ar – 20% CO2) and (90% Ar – 10% CO2) were made from test pieces cut from Sole bar material of Railway Coach. Study of Mechanical properties such as tensile strength, hardness and toughness revealed that welded joint made using shielding gas (80% Ar – 20% CO2) has better Mechanical properties compared to the other two shielding gases and comparable to that of Parent metal. Type of Shielding gas used has influence on the chemical composition and macro & micro structures. The Tafel extrapolation study of freshly ground samples in 3.5% NaCl solution revealed that the welded joint made using shielding gas (80% Ar – 20% CO2) has also better corrosion resistance which is comparable to the Parent metal as well as similar commercial steels.