who, when and where was dual phase steel invented?
Looking okorder /... but I would note that this stuff seems an awful lot like the techniques that have been used for making high quality swords and cutting tools for thousands of years including the famed Damacas steel. In these, the steel is heated and slowly cooled (annealed) to produce the tough matrix, then the piece is reheated and quenched to produce the hard edge. What Dual-phase seems to do is bring the process to bulk manufacture.
Dual Phase steels refers to a distinct group of alloys which are used for automotive bodies. These were developed to give improved deep drawing (for shaping) and strength while on the road. Most of the work was started at the same time in the 1970s as a response to the oil crisis (history repeats!) with SSAB in Europe, US Steel and British Steel leading the way. There are many variants of the dual phase alloys prefered by each of the auto manufacturers. The work on these steels led the way for TRIP (transformation induced plasticity) steels, rephosphorised steels and HSLA (high strength low alloy) steels. There is a distinction between these steels and duplex steels which typically refer to austenitic/ferrtic stainless steels. Also be aware that everyday low carbon steels with 0.1%-0.6% carbon will have a ferritic/pearlitic structure but are not considered to be dual phase So to summarise: Who - major steel companies worldwide When - from about 1973 onwards (up to around 1977 when the developments went in other directions) Where - Europe, USA and Japan (but I'm not sure who it was in Japan doing the work)
