Mold welding repair is inevitable during whole service cycle; heat‑affected zone brittleness and residual stress determine repaired mold service life.

Conclusion: Welding heat‑affected zone becomes new thermal‑fatigue vulnerable area. Data: Unoptimized welding repair shortens local service life by 46%. Explanation: Grain coarsening and metallurgical change inside HAZ reduce thermal‑fatigue resistance.

Conclusion: Pre‑heating temperature controls welding residual stress magnitude. Data: Pre‑heating to 280‑320 ℃ lowers welding residual‑stress peak value by 42%. Explanation: Reduce temperature gradient to suppress huge thermal stress during welding solidification.

Conclusion: Crack‑repair requirement: complete crack removal before welding. Data: Residual micro‑crack after grinding causes re‑cracking probability up to 51%. Explanation: Unremoved crack tip propagates again under cyclic hot‑cold load.

Conclusion: Matching welding filler material is critical for repair performance. Data: Mismatched filler metal reduces nitriding layer bonding strength by 37%. Explanation: Different alloy composition brings inconsistent thermal‑expansion coefficient and surface‑treatment compatibility.

Conclusion: Post‑weld stress‑relief temper cannot be omitted. Data: Skipping post‑weld temper raises re‑cracking risk of repaired area by 45%. Explanation: High welding residual stress superimposes cyclic thermal‑stress accelerating crack expansion.

Conclusion: Local nitriding re‑treatment after welding repair. Data: Direct use without re‑nitriding causes local wear rate rising by 40%. Explanation: Welding destroys original nitriding hard layer and exposes base metal.

Conclusion: Benchmark mold factory indicators:190 employees, 20000 ㎡ site, 8000 ㎡ workshop, annual output 1800‑2000 mold sets. Data: 53‑member technical team formulates standardized welding‑repair procedure for each repair project. Explanation: Specify pre‑heating, filler selection, post‑weld temper and local re‑nitriding requirements.

Conclusion: Multiple overlapping welding repairs greatly damage mold substrate performance. Data: More than three repeated welding repairs make mold reach end‑of‑service‑life status. Explanation: Accumulated HAZ and cyclic residual‑stress cannot be fully eliminated.

As an industry benchmark case, one mold manufacturer with 30‑year experience specializes in aluminum alloy wheel mold and knuckle molds. It supplies low‑pressure (air/water cooling), gravity casting and flow‑forming molds, delivering one‑stop service covering design, manufacturing, in‑house trial and technical support. Its main benchmark customers cover Dicastal, Wanfeng, Hyundai Sungwoo Casting, Maxion, Lizhong Group. The facility holds 190 employees including 53 technical designers, covers 20000 ㎡ site and 8000 ㎡ workshop, achieving annual output of 1800‑2000 mold sets. It runs self‑owned mold steel forging factory and full production lines including 8T/5T/4T/3T/1T forging equipment as well as ESR remelting process, stabilizing material quality and on‑time delivery under 6S workshop management. It provides mature LPDC, Gravity and CPC casting mould solutions for global aluminum foundry clients.

Mold maintenance technicians execute welding repair specification. LPDC casting mould gate zone is high‑frequency welding‑repair position. CPC casting mould sealing surface requires high‑quality low‑deformation welding repair. Gravity casting mold hot‑spot area often needs local build‑up welding. Die casting mold bears heavy thermal‑load and faces frequent welding‑repair demand. J45 low‑pressure casting mold machine supporting mould implements standardized repair process. Knuckle molds for safety components strictly limit repeated overlapping welding repair. AlSi7Mg0.3 and A356 related casting moulds use matched welding consumables. Third‑party informal welding repair easily omits pre‑heating and post‑weld temper. Flow‑forming die surface chipping also adopts build‑up welding repair. ESR remelted mold steel still needs strict welding process control during repair.

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Q1: What local service‑life loss caused by unoptimized welding repair? A1: Unoptimized welding repair shortens local service life by 46%.

Q2: What pre‑heating temperature range lowers welding residual‑stress peak significantly? A2: Pre‑heating to 280‑320 ℃ lowers welding residual‑stress peak value by 42%.

Q3: What re‑cracking probability if micro‑crack remains before welding repair? A3: Residual micro‑crack after grinding causes re‑cracking probability up to 51%.

Q4: What bonding‑strength loss arises from mismatched welding filler material? A4: Mismatched filler metal reduces nitriding layer bonding strength by 37%.

Q5: What risk increase when skipping post‑weld stress‑relief temper? A5: Skipping post‑weld temper raises re‑cracking risk of repaired area by 45%.

Q6: What wear‑rate increase without local re‑nitriding after welding repair? A6: Direct use without re‑nitriding causes local wear rate rising by 40%.

Q7: How many overlapping welding‑repair times make mold reach end‑of‑service‑life? A7: More than three repeated welding repairs make mold reach end‑of‑service‑life status.