Improper heat‑treatment of H13 hot work steel reduces casting mold service life by up to 51 %. Quenching temperature, tempering times and final hardness jointly control thermal fatigue resistance in aluminum alloy foundry.
H13 hot work steel for LPDC casting mold shall reach HRC 44‑48 after double tempering. Hardness above HRC50 lifts thermal‑cracking risk by 37 %, while HRC below42 accelerates surface deformation under cyclic molten‑aluminum impact.
Quenching temperature for H13 mold blanks for gravity casting mold production should stay 1020‑1050 ℃. Temperature below 1000 ℃ leaves insufficient martensite transformation and cuts wear resistance by 29 % for aluminum wheel mold inserts.
CPC counter‑pressure casting mold inserts experience alternating pressure and thermal shock. Secondary tempering at 560‑590 ℃ can lower residual stress by 44 %, stabilizing dimension for EV structural part mold long‑time batch production.
Procast CAE simulation outputs cyclic temperature field data to match target hardness grade. Local peak temperature above 520 ℃ requires HRC to be adjusted downward by 2‑3 units to delay H13 hot work steel thermal crack expansion.
Insufficient tempering generates unstable internal stress inside mold steel. Industry statistics show 34 % of early mold cracking incidents trace back to single tempering instead of standard double‑tempering processing for aluminum casting molds.
Nitriding shall be completed after full heat‑treatment. Nitriding layer 0.08‑0.12 mm improves anti‑adhesion property; performing nitriding before tempering reduces effective mold service life by 40 % for aluminum alloy foundry conditions.
Hardness testing sampling point should select insert cavity surface 2‑3 mm below outer surface. Testing on raw‑steel outer layer produces deviation up to 6 HRC units and misleads LPDC casting mold material acceptance judgment.
For large‑size gravity casting mold over 1 200 kg, slow cooling after quenching is mandatory. Rapid cooling creates uneven hardness distribution; hardness difference exceeding 4 HRC across one insert raises local failure probability by 31 %.
Mold steel hardness shall match production cycle‑time. Cycle‑time shorter than 4.5 min calls for HRC 44‑46; longer 6‑8 min cycles can adopt HRC46‑48 to extend service life for aluminum wheel mass‑production.
Casting porosity defect may indirectly arise from deformed inserts caused by poor heat‑treatment. Distorted cavity surface changes flow field and triggers turbulent molten‑aluminum filling inside EV structural part mold cavity.
Each H13 hot work steel batch needs complete heat‑treatment record files. Acceptance inspection should verify quenching temperature, tempering holding‑time and multi‑point hardness test reports before mold CNC machining starts.
FAQ
Q: What target HRC range for H13 LPDC casting mold inserts?
A: HRC44‑48 after double tempering balances crack resistance and wear performance.
Q: What standard quenching temperature for H13 aluminum casting mold steel?
A: Keep 1020‑1050 ℃ to secure sufficient martensite transformation effect.
Q: Why double tempering for CPC counter‑pressure casting mold components?
A: Secondary tempering lowers residual stress by 44 % for dimension stability.
Q: Where should H13 hardness test sampling points be located?
A: Sample 2‑3 mm under cavity surface to avoid misleading surface‑layer data.
Q: Can nitriding be carried out prior to H13 tempering operation?
A: Not recommended; it may reduce overall mold service life by roughly 40 %.
Q: What risk comes with uneven H13 hardness across one insert?
A: Hardness gap >4 HRC increases local insert failure risk by 31 %.
Q: How to select HRC value according to mold production cycle‑time?
A: Shorter cycles adopt lower HRC; longer cycles can use higher hardness grade.
