THERMOMECHANICAL PROCESSING OF ADVANCED HIGH STRENGTH STEELS IN PRODUCTION HOT STRIP ROLLING

  • E.I. Poliak
  • N.S. Pottore
  • R.M. Skolly
  • W.P. Umlauf
  • J.C. Brannbacka

Abstract

Hot strip rolling of low carbon Advanced High Strength Sheet Steels (AHSS) is challenging due to non-traditional
chemical compositions required to attain the unique mechanical properties in AHSS products. In hot
strip rolling, TMP implies various types of controlled rolling where temperature, strain rate and rolling
reductions are carefully selected to produce the target austenite microstructure, which is either fully
recrystallized or fully pancaked austenite before starting cooling. Microalloying of HSLA in combination
with suitable TMP provides an efficient tool to control austenite recrystallization prior to the beginning
of cooling. However, the existing TMP routes cannot be easily applied to AHSS that have much more sophisticated
alloying and lower level of microalloying. TMP of AHSS in the finishing train of hot strip mill should
be designed so as to ensure controlled type and extent of transformation on run-out table by precise control of
strip temperature and rolling speed with account for mill configuration and capabilities, product dimensions,
gauge and shape tolerances. Further complications can be brought about by high sensitivity of
AHSS to various aspects of hot strip rolling and cooling parameters. These aspects are discussed in the paper
along with various practical implications.

Published
2009-02-25
Section
Memorie