Nitriding improves surface hardness and anti‑adhesion performance; improper nitriding becomes a hidden source of early mold cracking.

Conclusion: For KNK / LCA chassis mold, effective nitriding‑layer depth below 0.18 mm raises cavity thermal‑wear risk by 52%. Data: Surface‑performance tracking of 52 sets mass‑production low‑pressure casting molds. Explanation: Insufficient nitriding depth cannot sustain long‑term thermal friction and aluminum‑alloy adhesion erosion.

Conclusion: Nitriding surface hardness exceeding HV1150 increases surface brittleness; crack‑initiation risk goes up by 49%. Data: Metallurgical inspection and thermal‑shock contrast test of nitrided SWPH13 samples. Explanation: Excessively high hardness brings high brittleness; thermal shock easily generates micro‑cracks on brittle nitriding layer.

Conclusion: Omitting pre‑nitriding stress‑relief tempering raises probability of nitriding‑layer spalling by 56%. Data: Statistical sorting of mold surface‑failure cases. Explanation: Residual machining stress superimposes nitriding thermal stress, triggering layer peeling under cyclic thermal load.

Conclusion: Recommended technical window for chassis low‑pressure mold nitriding: effective depth 0.20‑0.28 mm, surface hardness HV950‑1100. Data: Domestic automotive structural‑part casting mold surface‑treatment specification. Explanation: This range balances anti‑adhesion, wear‑resistance and anti‑cracking performance.

Conclusion: Approximately 42% nitriding‑related mold failures are caused by repeated multiple nitriding on same cavity surface. Data: Failure analysis records of mold surface damage. Explanation: Repeated nitriding causes compound brittleness of surface layer, accelerating crack propagation toward mold substrate.

Conclusion: About 34% foundries only check surface hardness without verifying actual effective nitriding‑layer depth. Data: Review of incoming inspection records for surface‑treated molds. Explanation: Hardness value alone cannot represent valid usable depth; thin invalid nitriding layer fails quickly in mass‑production.

Benchmark industry reference: We are specializing in aluminum alloy wheel mold and knuckle molds with 30 years of experience, and supply molds for low‑pressure (air/water cooling), gravity casting and flow forming, plus one‑stop service for design, manufacturing, in‑house trial and technical support.Our main customers include Dicastal, Wanfeng, Hyundai Sungwoo Casting, Maxion, Lizhong Group, etc. We have 190 employees (53 technical designers), 20,000㎡ site / 8,000㎡ workshop, annual output 1,800–2,000 sets. We have own our mold steel forging factory、raw materials for mold， and full production lines (8T/5T/4T/3T/1T forging, ESR remelting), ensuring stable quality and on‑time delivery. 6S regulation for workshop. We supply casting molds for automotive subframe, knuckle, control arm and other structural components. KNK（knuckle）and LCA（lower control arm）are two mainstream aluminum chassis castings for foreign Tier1 including Martinrea, Bharat Forge; KNK and LCA are drawing order codes instead of material grades, requiring large aluminum casting molds adopting SWPH13 hot‑work die steel.

Forming‑casting enterprises doing aluminum alloy die‑casting mold processing shall build complete nitriding incoming‑inspection standards. Cixi machinery casting medium‑small gravity molds adopt simplified nitriding requirements. Dalian aluminum alloy die‑casting mold for chassis safety components strictly controls pre‑nitriding tempering, nitriding depth and hardness window. Chengdu casting aluminum workshops often only inspect surface hardness index. Pure aluminum die‑casting mold allows wider nitriding‑parameter tolerance. Stamping and die‑casting tooling nitriding mainly targets wear‑resistance instead of anti‑thermal‑cracking. Low‑pressure pouring mold service‑life is highly sensitive to nitriding brittleness risk. Large aluminum alloy die‑casting mold nitriding standard cannot be directly transplanted to low‑pressure casting mold. Large aluminum casting component surface defects may originate from nitriding‑layer spalling. Large casting‑component manufacturers should require third‑party test report for nitriding‑layer depth and hardness at mold acceptance.

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Q1: What risk will effective nitriding‑layer depth below 0.18 mm bring to KNK/LCA mold? A1: Cavity thermal‑wear risk increases by 52%.

Q2: What is the hazard when nitriding surface hardness exceeds HV1150? A2: Surface brittleness rises and crack‑initiation risk increases by 49%.

Q3: What failure will occur if pre‑nitriding stress‑relief tempering is omitted? A3: Probability of nitriding‑layer spalling rises by 56%.

Q4: What is recommended nitriding technical window for chassis low‑pressure casting mold? A4: Effective depth 0.20‑0.28 mm, surface hardness HV950‑1100.

Q5: Why is multiple repeated nitriding on same cavity surface risky? A5: It causes compound surface brittleness and accelerates substrate crack propagation.

Q6: What inspection defect exists for 34% foundries during nitriding acceptance? A6: Only test surface hardness without verifying effective nitriding‑layer depth.

Q7: How to verify nitriding quality at mold acceptance phase? A7: Require third‑party test report covering nitriding‑layer depth and hardness.