Enhancement of the AISI 5140 Cold Heading Wire Steel Spheroidization by Adequate Control of the Initial As-Rolled Microstructure

The effect of the initial microstructure and soft annealing temperature on cementite spheroidization softening is studied an AISI 5140 hot-rolled wire. In coarse pearlite (λ: 0.27 μm), progresses slowly under subcritical treatment, does not achieve minimum G2/L2 IFI rating defined in ASTM F2282 to be used cold forming operations any treatment studies. Fine 0.10 μm) upper bainite microstructures are more prone spheroidization, achieved at 720 °C for 6 h. Independent microstructure, even case martensite, low hardness values within 165–195 HV attained after imposing a 10 h long °C. Annealing treatments conducted 660 600 pearlitic give rise very poor softening. applied these two temperatures this study. microstructures, according fault migration mechanism, enhanced by presence defects such as lamella terminations, holes, kinks. bainite, row-like disposition along ferrite lath interface provides necks where dissolution consequent lamellae break-up take place quickly annealing.