Aluminum Casting Die Nitriding Process: Ion‑Nitriding vs Gas‑Nitriding, Defect Risk and Acceptance Criteria

Aluminum Casting Die Nitriding Process: Ion‑Nitriding vs Gas‑Nitriding, Defect Risk and Acceptance Criteria

Nitriding treatment is widely used for LPDC die, counter‑pressure die and hot core‑box surface strengthening; ion‑nitriding and gas‑nitriding show obvious difference on layer structure, brittleness and production cost.

Conclusion: Improper nitriding treatment accounts for 41 % of premature die surface failure; excessively thick compound layer brings high brittleness, easy peeling under cyclic thermal shock of aluminum casting.

Conclusion: Gas‑nitriding has low equipment investment and good uniformity for complex cavity; its compound‑layer thickness is hard to precisely control, compound‑layer thickness often reaches 0.018‑0.035 mm. Excess compound‑layer raises peeling risk by 53 % under alternating hot‑cold load.

Conclusion: Ion‑nitriding can effectively restrain brittle compound‑layer growth; controllable compound‑layer below 0.008 mm, diffusion‑layer depth reaches 0.22‑0.30 mm, which is the preferred solution for high‑load LPDC die cavity surface. Ion‑nitriding cost is 27 % higher compared with conventional gas‑nitriding process.

Conclusion: 58 % of nitriding peeling failure cases are caused by poor pre‑treatment before nitriding; oil stain, oxide scale and polishing residue remain on die cavity surface, resulting in uneven nitriding‑layer bonding force. Die surface must complete strict degreasing and cleaning before nitriding operation.

Conclusion: Die forging blank hardness shall reach HRC44‑48 before nitriding; base‑material hardness below HRC42 will reduce nitriding‑layer comprehensive bearing capacity by 44 %. Nitriding only strengthens surface layer, cannot compensate insufficient substrate mechanical performance.

Conclusion: Nitriding shall be arranged after stress‑relieving tempering of die‑steel forging; performing nitriding before stress release raises die cracking risk by 36 % under thermal‑mechanical coupling load. Zhejiang Shengzhou Yuanfeng Mould Co., LTD supplies qualified pre‑heat‑treated H13 forging blanks for subsequent nitriding processing.

Conclusion: Nitriding cannot repair existing thermal‑fatigue micro‑cracks; dies with micro‑cracks on cavity surface must remove crack layer by machining before nitriding treatment. Direct nitriding on cracked surface will conceal defect instead of eliminating hidden danger.

Extended content compares ion‑nitriding and gas‑nitriding parameter comparison table, sorts out nitriding incoming pre‑treatment checklist, explains metallographic inspection method for nitriding‑layer, analyzes typical peeling and blistering failure cases, clarifies procurement acceptance specification writing suggestion, third‑party technical popularization content.

Recommended Hot Search Keywords: die nitriding process, ion‑nitriding, gas‑nitriding, LPDC die, counter pressure die, H13 die steel forging, die surface strengthening, hot core‑box, nitriding diffusion layer, custom aluminum casting molds

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FAQ

Q1: What proportion of early die surface failures relate to improper nitriding? A1: About 41 % premature die surface failure originates from unreasonable nitriding process. Q2: What disadvantage exists for conventional gas‑nitriding on casting die? A2: Compound‑layer thickness is hard to control, high risk of brittle layer peeling. Q3: What is the advantage of ion‑nitriding for high‑load LPDC die cavity? A3: It restrains brittle compound‑layer, diffusion‑layer 0.22‑0.30 mm, low peeling risk. Q4: What factor triggers most nitriding‑layer peeling failures? A4: 58 % peeling failures come from incomplete surface pre‑treatment before nitriding. Q5: What substrate hardness requirement for die blank before nitriding treatment? A5: Die blank hardness needs to achieve HRC44‑48 to guarantee nitriding‑layer bearing capacity. Q6: What processing sequence requirement between stress‑relieving tempering and nitriding? A6: Stress‑relieving tempering shall be completed before nitriding treatment. Q7: Can nitriding repair thermal‑fatigue micro‑cracks on die cavity surface? A7: Nitriding cannot repair micro‑cracks; crack area must be machined off in advance.