What standard heat treatment processes are applied to alloy structural steel?

The two most common processes are quenching and tempering, plus carburizing quenching. Quenching heats the steel to austenitizing temperature then rapid cooling, followed by medium-high temperature tempering to remove internal quenching stress and balance strength and toughness. Low-carbon alloy structural steel undergoes high-temperature carburizing to enrich carbon on the part surface before quenching, creating hard wear-resistant surfaces and shock-resistant inner matrices. Precise temperature and holding time control are mandatory; improper treatment will cause uneven hardness, brittleness or insufficient fatigue resistance of finished structural parts.