SUS630 exhibits distinct performance gradients after solution and different-temperature aging treatments. Heat treatment also affects corrosion resistance, magnetism, and other properties.
1. Performance after solution treatment
* Temperature range: 1020–1060℃, followed by rapid cooling.
* Hardness: ≤363 HB and ≤38 HRC; low hardness provides good machinability.
* Mechanical properties: tensile strength is relatively low, but plasticity is excellent, facilitating cutting, stamping, and other machining operations.
* Microstructure: forms uniform martensite, preparing the material for subsequent aging strengthening.

2. Performance after aging treatment
* Must be conducted after solution treatment. Different aging temperatures produce different mechanical properties: higher temperatures reduce strength and hardness while improving plasticity and toughness.
* 480℃ aging: strong strengthening effect. Tensile strength ≥1310 MPa, yield strength ≥1180 MPa, hardness ≥375 HB / ≥40 HRC, elongation ≥10%, reduction of area ≥40%. Suitable for high-strength and high-hardness applications.
* 550℃ aging: balanced performance. Tensile strength ≥1060 MPa, yield strength ≥1000 MPa, hardness ≥331 HB / ≥35 HRC, elongation ≥12%, reduction of area ≥45%. Widely used in industry.
* 580℃ aging: improved toughness. Tensile strength ≥1000 MPa, yield strength ≥865 MPa, hardness ≥302 HB / ≥31 HRC, elongation ≥13%, reduction of area ≥45%. Suitable for components requiring high toughness with moderate strength.
* 620℃ aging: optimal toughness. Tensile strength ≥930 MPa, yield strength ≥725 MPa, hardness ≥277 HB / ≥28 HRC, elongation ≥16%, reduction of area ≥50%. Ideal for applications with strict toughness requirements.

3. Effects of heat treatment on other properties
* Corrosion resistance: aging improves resistance to atmosphere, dilute acids, and saline environments, comparable to 304 stainless steel, suitable for mild corrosive conditions in chemical or marine applications.
* Magnetism: weak in solution-treated state, becomes strong after aging as the structure transforms to martensite. Useful for magnetic applications or sorting.
* High-temperature stability: stable below 300℃; above 350℃, precipitates coarsen, reducing strength. Avoid prolonged exposure to 400–450℃ to prevent “475℃ embrittlement,” which significantly reduces impact toughness.