Journal of Failure Analysis and Prevention

, Volume 13, Issue 4, pp 396–402 | Cite as

Pinch Roller Failure Analysis and Resulting Enhancement of Rebar Mechanical Properties

  • Souvik Das
  • Piyas Palit
  • Suman Mukhopadhya
  • Jitendra Mathur
  • Arthita Dey
  • Goutam Mukherjee
  • Tanmay Bhattacharyya
  • Sandip Bhattacharyya
Case History---Peer-Reviewed

Abstract

Reinforcing bars, popularly termed “rebars,” are used to impart tensile strength to concrete structures. Concrete has high resistance to weathering and fire and high compressive strength but almost no tensile strength, hence rebars are used to provide the latter to concrete. Property consistency along the length of rebars is an important prerequisite. When the finished product is subjected to thermomechanical treatment (TMT), proper control of rolling and water box parameters and efficient pinch rolling are needed to achieve acceptable properties. Variation of yield strength (YS) along TMT bars from the front to back end has been observed within the same heat treatment. In the presented investigation, it was observed that pinch rolling ineffectiveness is the main reason for the poor mechanical properties at the back end. The pinch roller was unable to support the back end of the TMT bars properly to maintain the speed and tension of the bars, resulting in nonuniform cooling of the back end through the water box and subsequent mechanical property failure. Due to the substandard material of the pinch roller, it was unable to hold the back end of the bar properly. Based on analysis of the roller it was concluded that it failed due to improper microstructure, resulting in inadequate hardness and toughness for the stringent operating conditions. AISI H13 is a better material to use in such high-service-temperature conditions. Moreover, proper heat treatment is needed to achieve adequate hardness and microstructure properties. After proper heat treatment of pinch rollers, their service life was increased twofold, minimizing the YS variation along the rebars.

Keywords

Thermomechanical treatment Yield strength Pinch rolling H13 grade 

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Copyright information

© ASM International 2013

Authors and Affiliations

  • Souvik Das
    • 1
  • Piyas Palit
    • 1
  • Suman Mukhopadhya
    • 1
  • Jitendra Mathur
    • 1
  • Arthita Dey
    • 1
  • Goutam Mukherjee
    • 1
  • Tanmay Bhattacharyya
    • 1
  • Sandip Bhattacharyya
    • 1
  1. 1.Metallurgical Laboratories and QA Group, R&D and Scientific ServicesTata Steel LimitedJamshedpurIndia

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