Resistance spot welding method and method for producing resistance spot welded joint

A resistance spot welding method in which a sheet combination of two or more overlapping steel sheets is sandwiched between a pair of electrodes and joined together by applying current while applying pressure, the method comprising:

• a main current application step in which current application is performed with a current Iw (kA);
• and
• subsequently, a post-tempering heat treatment step in which after cooling is performed for a cooling time tct (ms) shown in formula (1) below, current application is performed with a current It (kA) shown in formula (2) below for a current application time tt (ms) shown in formula (3) below, and
• between the main current application step and the post-tempering heat treatment step, a post-segregation reduction heat treatment step in which after cooling is performed for a cooling time tco (ms) shown in formula (4) below, current application is performed with a current Io (kA) shown in formula (5) below for a current application time to (ms) shown in formula (6) below,
• wherein at least one steel sheet in the sheet combination has a composition containing 0.08≤C≤0.3 (% by mass), 0.1≤Si≤0.8 (% by mass), 2.5≤Mn≤10.0 (% by mass), and P≤0.1 (% by mass), with the balance being Fe and unavoidable impurities:
• 800≤tct formula(1),
• 0.5×Iw≤It≤Iw formula (2),
• 500≤tt formula (3),
• 10≤tcp formula (4),
• 0.6×Iw≤Ip≤0.99×Iw formula (5), and
• 400≤tp formula (6).