The Energy Absorption Effect And Microstructure Evolution Of High Speed Steels Under High Pressure

The quality of rollers determines the economic efficiency of steel industry, since they are the part easy to wear during plate production. In order to improve the service life of the rollers, high-speed steels containing lots of high harness and wear-resistant carbides have become a development trend of roller materials. High-speed steel rollers directly interact with the rolled pieces during plastic deformation. In other words, they undergo high pressures from the rolled pieces, must followed by the absorption and release of energy, and thus this must have an effect on the microstructure and properties of high-speed steels.Three types of sand castings are used to produce high-speed steels, namely roller materials. By compression and indentation tests, energy absorption behaviors of the high-speed steels and carbides are researched under high stress. XRD, SEM and TEM analysis were performed on energy absorption and its influence on microstructure of high-speed steels. The results are as follows:All high-speed steels of V10, W10 and Mo10 consist of carbide, residual austenite and martensite after heating treatment. Carbides in high-speed steel V10 are spherical MC, in W10 are fishbone-like M6 C, and in plate high-speed steel Mo10 are lamelliform M2 C. The substrates of high-speed steels also are dotted with a large number of secondary precipitations of carbides. Carbides as strengthening phases disperse in the steels, their type, shape, size, structure and other factors have an effect on the properties of the materials.Under 1000 MPa,V10, W10,Mo10 high-speed steels and control Cr20 absorbed energy with increased stress increases along a quadratic form; with the number increasingly of compression, various materials absorbed energy reduction, when the material is no longer able to absorb more energy and stress continue to bite, it will deform and consider failures such as cracks or breaks. Actual requirements under cyclic high stress of rolls, W10 high-speed steel absorb highest energy, Mo10 V10 high-speed steel HSS, and were above the Cr20 absorb energy, so the cycle of three high-speed steel to withstand more stress, has a longer service life.Compared to W10, the type of carbides and matrix in Mo10, Cr20 and V10 in the MC in energy absorption aspects has a good match, it is believed that because MC type carbide have a high hardness and load uninstall elastic recovery big, has good of energy dissipation capacity, and matrix absorption energy induced has horse’s body phase variable, matrix absorption of energy was horse’s body phase variable process consumption off, V10 high-speed steel carbide and matrix energy absorption capacity difference is unlikely to, V10 high-speed steel under high stress absorption energy absorption and dissipation by matrix and MC carbides, effectively delaying the initiation of cracks.The nano creep experiment showed that the displacement from creep in V10 is minimum, and creep sensitive indexes of the carbides in the V10, W10, Mo10 and Cr20 are 0.01296, 0.01549, 0.01556 and 0.01937, respectively. The index of V10 less than that of others reveals it does not easily deform and possesses a longer service life under high pressure.Energy absorption under high pressure is beneficial to the transition from austenite to martensite in V10, W10 and Mo10 high-speed steels. The energy consumption and carbides operate an inhibition effect on crack initiation or expansion.