Characteristics of SKD61 Hot Work Mold Steel
Mechanical Properties and Thermal Stability
Room-Temperature Performance
Hardness: Approximately HRC15–20 (HB200–230) before heat treatment; reaches HRC56–58 after quenching, with surface hardness of HV1000±100.
Strength and Toughness:
Tensile strength ≥ 585 MPa
Yield strength ≥ 415 MPa
Elongation after fracture: Longitudinal ≥ 20%, transverse ≥ 18%
Impact energy: Longitudinal ≥ 40 J, transverse ≥ 27 J
Balances high strength with excellent impact resistance.
High-Temperature Performance
Endurance Strength: Exceeds 100 MPa under 625°C/10⁵h conditions, meeting long-term service requirements for high-temperature environments such as supercritical power units.
Thermal Stability: Maintains superior strength at 600°C, suitable for critical components like boiler superheaters and reheaters.
Thermal Fatigue Resistance: Resists the formation of network cracks (crazing) during repeated heating and cooling cycles, extending mold service life.
Processability and Adaptability
Heat Treatment Processes
Quenching: Air cooling at 1020–1050°C, with minimal heat treatment distortion. Surface nitriding can be applied to enhance wear resistance.
Tempering: Triple tempering at 550–680°C to optimize the balance of strength and toughness.
Cryogenic Treatment: Held at -70 to -80°C for 3–4 hours to increase hardness by 1–3 HRC and improve dimensional stability (but precautions are needed to prevent cracking in complex-shaped parts).
Welding and Forming Performance
Weldability: Achieves crack-free welding by controlling carbon equivalent, preheating, and post-weld heat treatment, using matching filler materials such as ER90S-B9 specialized welding wire.
Forming Methods:
Hot Rolling: High production efficiency and low cost.
Cold Drawing: Suitable for high-precision applications but with higher costs.
Surface Treatment
Nitriding: Forms a high-hardness surface layer, significantly improving wear resistance and corrosion resistance for extrusion dies and facilitating rapid demolding in die-casting molds.
