Research and Development > Technical Report > No.11 Special Issue on Steel Plates > Recent Development in Microstructural Control Technologies through the Thermo-Mechanical Control Process (TMCP) with JFE Steel’s High-Performance Plates

No.11 Special Issue on Steel Plates

Recent Development in Microstructural Control Technologies through the Thermo-Mechanical Control Process (TMCP) with JFE Steel’s High-Performance Plates

SHIKANAI Nobuo     MITAO Shinji     ENDO Shigeru

Abstract

Thermo-mechanical control process (TMCP) is a microstructural control technique combining controlled rolling and cooling. Thermo-mechanical control process is used to obtain excellent properties for steel plates, such as high strength, excellent toughness, and excellent weldability. JFE Steel has been developing TMCP technologies ever since it started operating its accelerated cooling facility, OLAC^® (On-Line Accelerated Cooling), in its plate mill at West Japan Works (Fukuyama) in 1980 (the world’s first industrial accelerated cooling system ever built). In 1998, JFE Steel developed Super-OLAC, an advanced accelerated cooling system capable of cooling plates homogeneously at high cooling rates close to the theoretical limits. In 2004, the epochmaking on-line induction heating facility, HOP^® (Heattreatment On-line Process), was also installed in the plate mill at West Japan Works (Fukuyama). Highstrength steels, a grade of steel usually produced by the quenching and tempering (Q-T) process, can be toughened by refining the component carbides through rapid tempering by HOP. Because Super-OLAC is capable of accurately controlling the stop cooling temperature before tempering, JFE has managed to develop a new set of microstructural control techniques using M-A (martensite-austenite constituent) as the hard phase. These are unique techniques unachievable with the conventional Q-T process or conventional TMCP. These techniques have already been applied to various advanced products. In this paper, the fundamentals of microstructural control by TMCP, and the recent development of TMCP are described. Examples of the advanced high-strength plates produced in JFE Steel are also presented.

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