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<p>The production cost of aluminium die casting is largely influenced by the raw materials used for die steel. This contribution introduces a&#xa0;novel, cost-effective hot work die steel, SDH68. The findings indicate that SDH68 improves the evolution of carbides at high temperatures by optimising its alloy composition. High-Cr H11 precipitates significant amounts of Cr-rich carbides during tempering. Under thermal cycling, these precipitates rapidly coalesce and grow, resulting in accelerated dislocation recovery and softening of the matrix. The annihilation of dislocations accelerates the accumulation of cyclic plastic strain, ultimately causing die failure. After holding at 600 °C for 40 h, the average size of the precipitates in SDH68 remains at 87 nm, whereas in H11, it grows to 108 nm. The finer precipitates effectively impede the reduction in dislocation density, contributing to a&#xa0;higher strength. Consequently, after 1500 thermal fatigue cycles, the fatigue damage factor of SDH68 is only 60% of H11, demonstrating a&#xa0;superior resistance to thermal fatigue.</p>

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Mechanical Properties and Thermal Fatigue Behaviour of a Novel Hot Work Tool Steel SDH68 for Die Casting Applications

  • 期刊论文

  • 发表日期：

    2025年8月7日

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  • Bingchen Li,
  • Xiaochun Wu

摘要

The production cost of aluminium die casting is largely influenced by the raw materials used for die steel. This contribution introduces a novel, cost-effective hot work die steel, SDH68. The findings indicate that SDH68 improves the evolution of carbides at high temperatures by optimising its alloy composition. High-Cr H11 precipitates significant amounts of Cr-rich carbides during tempering. Under thermal cycling, these precipitates rapidly coalesce and grow, resulting in accelerated dislocation recovery and softening of the matrix. The annihilation of dislocations accelerates the accumulation of cyclic plastic strain, ultimately causing die failure. After holding at 600 °C for 40 h, the average size of the precipitates in SDH68 remains at 87 nm, whereas in H11, it grows to 108 nm. The finer precipitates effectively impede the reduction in dislocation density, contributing to a higher strength. Consequently, after 1500 thermal fatigue cycles, the fatigue damage factor of SDH68 is only 60% of H11, demonstrating a superior resistance to thermal fatigue.