Microstructural characterization during the hot deformation of 1.17C–11.3Cr–1.48V–2.24W–1.35Mo ledeburitic tool steel

The hot-deformation behavior of 1.17C–11.3Cr–1.48V–2.24W–1.35Mo tool steel was studied. Hot-compression tests were carried out in the temperature range of 850–1200 °C, at strain rates in the range of 0.001–6 s− 1, and field-emission scanning electron microscope and optical microscopy were used for the microstructural characterization, which revealed a very complex precipitation of carbides that depends on the soaking temperature, the soaking time, the stress state, the deformation temperature as well as on the strain rate. A procedure for determining an appropriate soaking temperature, which enables an extension of the safe hot-working range, was developed. The soaking temperature and the time are the key factors controlling the hot workability. A study of the dissolution of ledeburitic carbides showed that there is a limit fraction to which the carbides could be dissolved prior to hot working without any negative influence on the hot workability. A revision of the general opinion about the influence of non-dissolved carbides on the hot workability is given.