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<p>This study investigates surface cracks in high-strength microalloyed steel produced <i>via</i> strip casting, combining experimental analysis with thermodynamic calculations to elucidate the cracking mechanism. The results demonstrate that as the Si and Mn content increases, the number of surface cracks rises from 31 to 39, with more cracks observed on the lower surface than the upper surface. In low-alloy samples (Si: 0.17 wt pct, Mn: 0.65 wt pct), the typical microstructure consists of pearlite, where cracks initiate at proeutectoid ferrite precipitates along prior austenite grain boundaries and propagate along these boundaries. In high-alloy samples (Si: 1.2 wt pct, Mn: 1 wt pct), the microstructure is predominantly bainitic, and cracks similarly initiate and propagate at proeutectoid ferrite near prior austenite grain boundaries. The primary cause of cracking under stress is the significant hardness difference between prior austenite grain boundaries and grain interiors. The increased Si and Mn content further amplifies this hardness contrast, thereby exacerbating surface crack formation.</p>

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Cracking Mechanisms in High-Strength Microalloyed Steel Produced via Strip Casting

  • 期刊论文

  • 发表日期：

    2025年11月24日

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  • Boquan Xie,
  • Qian Long,
  • Wanlin Wang,
  • Qingxiao Feng,
  • Chenyang Zhu

摘要

This study investigates surface cracks in high-strength microalloyed steel produced via strip casting, combining experimental analysis with thermodynamic calculations to elucidate the cracking mechanism. The results demonstrate that as the Si and Mn content increases, the number of surface cracks rises from 31 to 39, with more cracks observed on the lower surface than the upper surface. In low-alloy samples (Si: 0.17 wt pct, Mn: 0.65 wt pct), the typical microstructure consists of pearlite, where cracks initiate at proeutectoid ferrite precipitates along prior austenite grain boundaries and propagate along these boundaries. In high-alloy samples (Si: 1.2 wt pct, Mn: 1 wt pct), the microstructure is predominantly bainitic, and cracks similarly initiate and propagate at proeutectoid ferrite near prior austenite grain boundaries. The primary cause of cracking under stress is the significant hardness difference between prior austenite grain boundaries and grain interiors. The increased Si and Mn content further amplifies this hardness contrast, thereby exacerbating surface crack formation.