TMCP (Thermo-Mechanical Control Process) technology was developed in Japan 1980's. With the use of TMCP process, very fine and uniform acicular Ferrite is attained as microstructure. Therefore TMCP steels have higher strength and better toughness. Also according to TMCP process, lower hardenability, less susceptibility for cold cracking and the availability for the extra high heat input welding have been improved. Before start of the actual production of TMCP steels, we installed the sophisticated equipment and supporting system for TMCP. Consequently, Quality level of TMCP steels is quite high and mechanical properties of TMCP steels are very stable. Every year quite a lot of TMCP steels are produced and fabricated with no problem.
TMCP technology was introduced to most of Japanese Plate mills and TMCP steels have been widely applied to Japanese shipyards. The reason why Japanese shipyards accepted TMCP type HT (High Tensile strength) steels so quickly was that TMCP steels had the almost same formability and weldability compared with mild steels and superior mechanical properties. In this paper, the author describes the basic ideas of TMCP technology and the general properties of TMCP steels. HISTORY of TMCP TMCP technology was developed early in 1980's. Major Japanese plate mills started to produce TMCP steels middle of 1980's. According to the increase of application of TMCP steels, HT ratio increased very sharply (Fig.1). WHAT IS TMCP? In the past, the roll of hot rolling was only to achieve the nominal dimensions like thickness, width and length. According to the exact definition of TMCP after IACS (Fig.2), TMCP includes TMR (Thermo-Mechanical Rolling) and AcC (Accelerated Cooling). But when people speak of TMCP, they usually think of AcC as TMCP. Therefore from now on, the author intends to concentrate into AcC only. Consequently, if the author says TMCP, that means AcC.