| 摘要 |
PROBLEM TO BE SOLVED: To attain a high joint strength in resistance spot welding of a plate set including a Ti-added high Al content high strength low specific gravity steel plate.SOLUTION: When a plate set including high strength low specific gravity steel plate which has a specific gravity less than 7.5 and contains Ti carbonitride having a size of 0.05 to 3.0 μm by 5.0×10to 1.0×10pieces/mmis subjected to resistance spot welding, (1) such prior electric conduction that electric conduction is performed for 0.06 to 0.40 s and, after the electric conduction, electric conduction is paused for 0.02 to 0.10 s is performed at least one time, temperature of a portion to be welded is moderately raised, subsequently, (2) such main electric conduction that electric conduction is performed for 0.14 to 0.60 s with an electric current of 50 to 150% of welding electric current upon the prior electric conduction is performed one time, heat input upon the main electric conduction is reduced, thereby, dissolution of the Ti carbonitride existing in the high strength low specific gravity steel plate is suppressed and a high strength welded part (nugget) having a fine structure is formed. |
