Rolling contact fatigue performance of ductile iron improved by electric contact surface strengthening

► Surface of ductile iron was modified by electric contact heating (ECH). ► Fe3C, martensite and hardened shell around graphite were transformed after ECH. ► Higher hardness and residual compressive stress were observed in the modified zone. ► Ductile iron after ECH had the best fatigue lifetimes. ► Fatigue limit of ductile iron after ECH increased from 693 N/mm2 to 1054 N/mm2.