| 摘要 |
This invention relates to a method of induction heat treating and restraint quenching structural members, particularly those of low carbon alloy steel (lean content), to a uniform martensitic structure, such that distortion of the member due to rapid quenching is controlled. The members would generally be of a channel shape and they would be heated by induction preheating in several stages to austenitizing temperature, namely 1450 DEG to 1750 DEG F., and then liquid quenching the channel member and restraining the channel on both its web and its flanges to below 900 DEG F. to minimize distortion and then tempering the channel at a temperature of 750 DEG to 1000 DEG F. and again restraining it while cooling to avoid distortion. These would generally be truck side rails and they would be low carbon alloy steels (lean content), approximate carbon content of 0.22-30%, manganese 1.00 to 1.35%, sulfur 0.05% max., phosphorus 0.04% max., with minimum physical properties after heat treating of yield strength 110,000 psi and tensile strength 125,000 psi. The induction preheating is done at about 10,000 cycles. The inductors would be either hairpin coils, oval coils or possibly pancake coils.
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