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<p>Low-relaxation prestressed concrete (LRPC) wires are widely used in structural applications and are manufactured by multi-pass cold drawing, where microstructural uniformity and defect control play a crucial role in ensuring drawability and in-service reliability. This study investigates the root causes of repeated wire breakage through detailed microstructural, hardness, fractographic, and compositional analyses. The failed wires exhibited classic cup-and-cone ductile fracture morphology with microvoid coalescence, non-uniform pearlite interlamellar spacing, carbon enrichment at fracture surfaces, and pronounced centerline segregation in the parent rod, along with thin sulfide and globular oxide inclusions that acted as stress concentrators. To mitigate these defects, several steelmaking and casting parameters were optimized: The tundish superheat was maintained at 30–40&#xa0;°C above the liquidus temperature (1465&#xa0;°C) using circulation ladles, casting speed was reduced from 2.2 to 1.8&#xa0;m/min to stabilize shell formation, and EMS parameters were strengthened by increasing the frequency from 2 to 3&#xa0;Hz and current from 200 to 300&#xa0;A to improve strand quality. The secondary spray-cooling rate was increased from 1.6 to 2.3&#xa0;L/kg to enhance solidification control, while slag carryover was minimized by implementing a slag detection system and reducing casting sequence length from eight heats to four, thereby reducing tundish slag thickness from 50 to ~ 20&#xa0;mm. In addition, a submerged ladle-opening technique was adopted to prevent slag–metal emulsification and suppress secondary inclusion generation in the tundish. Implementation of these measures significantly reduced microstructural heterogeneity, improved steel cleanliness, and enhanced the overall drawability and performance of LRPC wires.</p>

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Minimization of Wire Breakage Failure of High Carbon Cord Application Grade

  • 期刊论文

  • 发表日期：

    2026年3月13日

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  • Rachappa Kadli,
  • Amarjeet Kumar Singh

摘要

Low-relaxation prestressed concrete (LRPC) wires are widely used in structural applications and are manufactured by multi-pass cold drawing, where microstructural uniformity and defect control play a crucial role in ensuring drawability and in-service reliability. This study investigates the root causes of repeated wire breakage through detailed microstructural, hardness, fractographic, and compositional analyses. The failed wires exhibited classic cup-and-cone ductile fracture morphology with microvoid coalescence, non-uniform pearlite interlamellar spacing, carbon enrichment at fracture surfaces, and pronounced centerline segregation in the parent rod, along with thin sulfide and globular oxide inclusions that acted as stress concentrators. To mitigate these defects, several steelmaking and casting parameters were optimized: The tundish superheat was maintained at 30–40 °C above the liquidus temperature (1465 °C) using circulation ladles, casting speed was reduced from 2.2 to 1.8 m/min to stabilize shell formation, and EMS parameters were strengthened by increasing the frequency from 2 to 3 Hz and current from 200 to 300 A to improve strand quality. The secondary spray-cooling rate was increased from 1.6 to 2.3 L/kg to enhance solidification control, while slag carryover was minimized by implementing a slag detection system and reducing casting sequence length from eight heats to four, thereby reducing tundish slag thickness from 50 to ~ 20 mm. In addition, a submerged ladle-opening technique was adopted to prevent slag–metal emulsification and suppress secondary inclusion generation in the tundish. Implementation of these measures significantly reduced microstructural heterogeneity, improved steel cleanliness, and enhanced the overall drawability and performance of LRPC wires.