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<p>To investigate the combined effect of pearlite colony size and cementite interlamellar spacing on the tensile properties of heavy-section pearlitic ductile iron under different air-atomized water mist rates, resolving heterogeneous cooling in conventional heat treatment and alleviating the intrinsic water-quench cracking propensity are imperative. A process both air-atomized water mist cooling and normalization at 900 ± 2 °C followed by tempering (N&amp;T) are proposed. Results demonstrated that increasing the air-atomized water mist rate from 20 m/s to 25m/s and 30 m/s refines the pearlite colony size from 18.3 μm to 16.8 μm and 16.4 μm, and the pearlite lamellar spacing exhibits values of 245 nm, 210 nm, and 213 nm, respectively. The higher cooling rates increase carbon concentrations in undercooled austenite, enhancing nucleation sites for cementite during solid-state phase transformation. Tensile strength values increase by 11%, 25%, and 19% compared to the as-cast state, measuring 710 MPa, 799 MPa, and 759 MPa, while elongation values remain closely to the as-cast specimens. The discontinuous cementite regions become the primary channels for dislocation slip deformation, disrupting the dislocation pinning effect at the ferrite–cementite interface. Consequently, the diminished capacity of high-angle grain boundaries (HAGBs) to impede dislocation movement induces the deflection of cracks from {100} cleavage planes to {110} cleavage planes. This transition inhibits the further enhancement of the tensile properties of heavy-section pearlitic ductile iron.</p>

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Combined Effects of Pearlite Colony and Interlamellar Spacing on the Tensile Performance in Heavy-Section Ductile Iron via Air-Atomized Water Mist

  • 期刊论文

  • 发表日期：

    2026年8月3日

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  • Wendong Xu,
  • Wei Zhang,
  • Xinming Liu,
  • Yihan Hao,
  • Yingdong Qu,
  • Siruo Zhang,
  • Shulin Dong,
  • Mengyu Wang,
  • Hongkui Zhang,
  • Guanglong Li

摘要

To investigate the combined effect of pearlite colony size and cementite interlamellar spacing on the tensile properties of heavy-section pearlitic ductile iron under different air-atomized water mist rates, resolving heterogeneous cooling in conventional heat treatment and alleviating the intrinsic water-quench cracking propensity are imperative. A process both air-atomized water mist cooling and normalization at 900 ± 2 °C followed by tempering (N&T) are proposed. Results demonstrated that increasing the air-atomized water mist rate from 20 m/s to 25m/s and 30 m/s refines the pearlite colony size from 18.3 μm to 16.8 μm and 16.4 μm, and the pearlite lamellar spacing exhibits values of 245 nm, 210 nm, and 213 nm, respectively. The higher cooling rates increase carbon concentrations in undercooled austenite, enhancing nucleation sites for cementite during solid-state phase transformation. Tensile strength values increase by 11%, 25%, and 19% compared to the as-cast state, measuring 710 MPa, 799 MPa, and 759 MPa, while elongation values remain closely to the as-cast specimens. The discontinuous cementite regions become the primary channels for dislocation slip deformation, disrupting the dislocation pinning effect at the ferrite–cementite interface. Consequently, the diminished capacity of high-angle grain boundaries (HAGBs) to impede dislocation movement induces the deflection of cracks from {100} cleavage planes to {110} cleavage planes. This transition inhibits the further enhancement of the tensile properties of heavy-section pearlitic ductile iron.