Organization And Performance Of C-Mn Steel In Warm Rolling Process

As traditional materials, steel faces other structural material competition, aluminum,titanium and their alloys and plastics gradually encroach on originally belongs to thedomain of the steel. In addition to the external competition, iron and steel industryinternal competition is forcing people to do everything possible to reduce cost, improvequality and strengthen the market competition ability through the control of steelstructure property. This requires steel not only has good surface quality, but alsoorganization mechanical properties of steel is put forward higher requirements. Thispaper through the research of organization transition mechanism in material warm rollingprocess, mechanical properties and process parameter control, for the purpose ofoptimization of organizational structure, organizational refinement, simplify theannealing process and shorten the cycle of spheroidization.At present the C-Mn steel (45steel,65Mn) warm rolling organization refining andphase change research reports are very few, technology formulating lack scientific basis.This paper using isothermal compression experiment, research C-Mn steel in550~700℃organization transformation and carbide precipitation change rule. It provides a reliablereference basis for the material warm deformation Process formulation.First of all, forecast the organization performance in warm rolling process betweenroughing and finishing cooling process. Organization modeling and analysis based onKRC (Kaufman Redcliffe Cohen) model for Phase transition thermodynamics basis andCahn theory and additivity rule for phase transformation kinetics during cooling process.Each phase equilibrium temperature and the volume fraction of each phase organizationsunder the influence of different cooling rates are calculated. Ferrite grain size model andpearlite spacing model were established, and verify the correctness of the model usingexperimental data.Secondly, through the thermal simulation experiment, the organizationtransformation process and mechanism in the warm process are analyzed. It is foundedthat the warm deformation process mainly occurres ferrite dynamic recrystallization and cementite spheroidization phenomenon. The law of organization transformation arediscussed and analyzed in different deformation process (deformation, deformationtemperature, deformation rate).Ferrite grains decreases with decreasing deformationtemperature, cementite with the deformation rate decreases. Study the influence on warmdeformation caused by the initial pearlite organization with different lamellar spacing dueto cold speed produce. In initial organization, flake carbide more fine, more irregular, thehigher the energy, the greater the broken breaking the driving force to accelerate thecarbide grainy tendency.Finally, the different warm deformation process of the specimen for mechanicalproperties (hardness, strength, elongation, fracture morphology) test. Through thecontrast analysis, performance of45steel at650℃,700℃is the best,65Mn indeformation temperature of600℃,650℃comprehensive mechanical performance isgood.