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Gourav Rao, A.
- Hot Tensile Properties of Filler Added Constant Current Gas Tungsten Arc Welded AISI 304HCu Super Austenitic Stainless Steel Joints
Authors
1 Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar, Tamil Nadu - 608002, IN
2 Naval Material Research Laboratory (NMRL), Ambernath, Mumbai - 421506, IN
Source
Indian Welding Journal, Vol 48, No 4 (2015), Pagination: 61-67Abstract
AISI 304HCu austenitic stainless steel containing 2.3 to 3 (% wt) of Cu is mainly used in superheaters and reheater of ultra super critical (USC) boilers which operates over 600°C of steam temperature. Austenitic stainless steels welded by gas tungsten arc welding (GTAW) alters the phase composition, and microstructure of the steel in the fusion zone of welds and may affect the mechanical properties. In our previous investigation, it is found that autogenous welding of AISI 304HCu tubes resulted in segregation of alloying elements in the weld metal and resulted in joints with inferior tensile strength. Hence, in this study the high temperature tensile properties of filler added GTA welded AISI 304HCu tube joints were evaluated and correlated with the microstructural features. The tensile strength of the filler added GTA weld joints was higher than the parent metal at all test temperatures and the weld joint with filler addition was recommended for application in USC boilers.Keywords
AISI 304HCu, Gas Tungsten Arc Welding, High Temperature Tensile Properties, Ultra Super Critical Boilers.- Microstructure Evolution and Mechanical Properties of Friction Stir Welded Thick HSLA Steel
Authors
1 Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra, IN
Source
Indian Welding Journal, Vol 51, No 3 (2018), Pagination: 54-58Abstract
Friction stir welding (FSW) is known for joining low softening alloys metals such as aluminum, magnesium and copper, however joining of high softening alloys like steel, titanium and nickel base alloys is still a challenge due to tool material stringent property requirements and its availability. Presently, due to development new generation tool material FSW of high softening alloys is possible and also reported. FSW can effectively join different grade of low thickness steel, however the questions about joining thick section steel still remains a challenge.
In this paper, FSW of 7 mm, 12 mm and 24 mm thick HSLA steel in single and double pass was carried out to develop the processing window for defect free weld joints and understanding the structure-property correlation. The increase in thickness of the base metal resulted in generation of higher load, higher heat input and consequently lower cooling rate. Therefore, the microstructure obtained after FSW in different thickness of steel also shows varying microstructures (grain boundary ferrite, acicular ferrite, widmensttan ferrite and upper bainite). Optical and scanning electron microscope (SEM) with electron back scattered diffraction (EBSD) detector was utilized to characterize the microstructure of FSW nugget zone. Tensile and hardness properties were also evaluated and correlated with the microstructure.
Keywords
Friction Stir Welding, High Strength Low Alloy Steel (HSLA), Microstructure, Tensile Properties, Scanning Electron Microscopy.References
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