Microstructure and Mechanical Properties of Weld Metals of 950MPa Class High-strength Steel(Materials, Metallurgy & Weldability, INTERNATIONAL SYMPOSIUM OF JWRI 30TH ANNIVERSARY)
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Gas metal arc weld metals of the 950MPa class high-strength steel were prepared in shielding gases with different CO_2 contents, and effect of CO_2 on the mechanical properties and microstructure of the weld metal was investigated. Vickers hardness and Charpy impact absorbed energy decreased with an increase of CO_2 content in the shielding gas. With the pure Ar shielding gas the weld metal showed lath martensite microstructure With an increase in the CO_2 content in the shielding gas the microstructure became bainitic, and with the 25%CO_2-Ar shielding gas a granular bainite structure was found. These changes were caused by the decrease in the hardenability of the weld metal with the decrease of alloy elements by the oxidation during the welding.
- Transactions of JWRI
Transactions of JWRI 32(1), 113-114, 2003-07