Research On Grain Refinement By Strain Induced Phase Transformation

The steel material is still a basic material in the industry, it has a wide source of abundant resources, recycling, it has a wide source of abundant resources, recycling high performance reliability, relative to other new materials cheaper price, easy processing characteristics. Iron and steel industry as one of the important industries, is an important support for other industries, with the rapid development of China's economic and social, the performance of steel made a higher demand. With the development of science and technology as well as modern industry,the steel component is developing in the direction of large scale and miniaturization, and the two directions have different requirements on the performance of steel materials. To improve the high performance of low carbon steel is an important direction in the research of iron and steel materials.With the development of science and technology, physical or chemical methods can be used to improve the performance of low carbon steel. Grain refinement is the most fundamental method to improve the properties of iron and steel materials at present. It can improve the low carbon steel and low alloy steel and toughness, and can replace part of alloy structural steel under the premise of ensuring the performance, so as to save a large amount of alloying elements. At the same time, the use of intermediate temperature processing technology can save energy, reduce the cost of investment and reduce the pollution of the environment.In this paper, the effect of strain induced ferrite transformation on grain refinement of 20 steel was studied. By studying the deformation parameters-(deformation temperature, strain and strain rate) effects on grain refinement in the strain induced ferrite transformation process, analyzing the stress-strain curve, comparing the image of the microstructure of the experimental material image, observing the change in three grain size, finally this paper obtained experimental results. The change of grain size was observed and compared with the deformation temperature, the deformation rate and the amount of deformation were obtained, which promoted the occurrence of strain induced ferrite transformation, and the grain size became smaller. Meanwhile this paper analyzes the strain induced ferrite phase transition in the thermodynamic and kinetic aspects. By the researches in the aspects of thermodynamic and kinetic, this paper obtains sometheoretical data for strain induced ferrite transformation in thermodynamics and kinetics. It can be concluded that the deformation storage energy and the average size of the grains after phase transformation. Strain-induced phase transformation is one of refinement mechanism of grain refinement mechanism. Researching strain induced phase transformation refinement mechanism and applying it to the actual forging production process have important theoretical significance and value to obtain high-strength fine-grained steel.