Microstructure Evolution and Mechanical Properties of Friction Stir Welded Thick HSLA Steel
Authors
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Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra ,IN
A. Gourav Rao -
Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra ,INA. P. Singh
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Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra ,INS. Parida
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Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra ,INA. Kumar
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Naval Metallurgy Division, Naval Materials Research Laboratory, Ambernath, Thane - 421 506, Maharashtra ,INV. P. Deshmukh
DOI:
https://doi.org/10.22486/iwj/2018/v51/i3/175006Keywords:
Friction Stir Welding, High Strength Low Alloy Steel (HSLA), Microstructure, Tensile Properties, Scanning Electron Microscopy.Abstract
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.
References
Shinoda T and Takegami H (2005); Development of FSW process for steel assembly to shipbuilding and offshore structure, Proc. 15th Int. Offshore and Polar Eng. Conf., Seoul, pp.19-24.
Show BK, Veerababu R, Balamuralikrishnan R and Malakondaiah G, (2010), Effect of vanadium and titanium modification on the microstructure and mechanical properties of a microalloyed HSLA steel, Materials Science and Engineering A, 527, pp. 1595–1604.
Rai R, De A, Bhadeshia HKDK and Debroy TT (2011); Review: friction stir welding tools, Science and Technology of Welding and Joining, 16(4), pp. 325-342.
Thompson B and Babu SS (2010), Tool degradation dharacterization in the friction stir welding of hard metals, Edison Welding Institute, 89, pp. 21-26.
Ragu Nathan S, Malarvizhi S, Balasubramanian V and Rao AG (2016), Failure analysis of tungsten based tool materials used in friction stir welding of high strength low alloy steels Engineering Failure Analysis, 66, pp. 88–98.
Ragu Nathan S, Malarvizhi S, Balasubramanian V and Rao AG (2015), Effect of welding processes on mechanical and microstructural characteristics of high strength low alloy naval grade steel joints, Defence Technology, 11, pp.308–317.
