Research On Online Pre-hardening Process Model Of Hot Rolled Flat Steel

With the development of heat treatment technology, The application ofPre-heat treatment hardening quenching has more and more attracted people’s attention.Steel production can be efficiently, environmentally-friendly, low-cycle and low-costthrough pre-hardened quenching process. Currently, a number of large domestic andforeign steel producers is use pre-hardened quenching process and bring significanteconomic benefits to the enterprises.This paper is based on heat transfer theory, solid-state phase transformation,transformation kinetics and do research on numerical simulation of pre-hardeningquenching process of mold flat steel SCM420with the finite element software COSMAP.Establishing the finite element model of the temperature field, organization field,stress field. Do the analysis of pre-hardening quenching. The main contents are asfollows:According to the available literature and data, it generalize and fitting calculatethermal physical parameters and boundary conditions of flat steel SCM420. UsingORIGIN to chart the relationship curve between specific heat, heat transfer coefficient,thermal conductivity and temperature, then deriving the empirical formula. Basing on thiscondition, it do the pre-hardening quenching simulation test on computer and greatlyreduces calculation error when do the simulation calculation with the conditions ofconstant.Based on the finite element simulation of SCM420flat steel, We can find the flatsurface cooling speed faster, create the martensite.But the core cooling rate is relativelyslow and create the bainite. When SCM420flat preliminary hardening quenchingtemperature at850℃-870℃, the mechanical properties is relatively good. Under theprocess conditions, The SCM420flat steel have a large flat surface hardness, a goodstrength, the heart of strong toughness and a good impact resistance.Having the test on the system of online Pre-hardening. Analysis its change oftemperature and hardness, observing quenching metallographic organization. Contrastwith the results of simulation, the results are consistent and verify the theoretical analysis.