| This paper presents a new method and principle for manufacturing straight cylind rical gear in order to improve production performance and productivity, reduce p roduction cost and energy consuming, and decrease environment pollution.The mechanical behavior and microstructure response during warm deformation of t he gear using 20CrMnTi steel have been studied firstly. We find that the materia l has better plasticity in the temperature range from 650℃ to 850℃; The deform ation inducing ferrite not only makes grain super refining, but also reduces flo w stress greatly at the temperature of 770℃. The effect of super refining can b e kept down in the heat treatment afterwords.The principle of "successive control deformation" and the method to realize "rad ial shunt, axial diversion and open filling" of the principle have solved the ke y problem of deforming for straight cylindrical gear. Proved by small lot produc tion, the set technology and the designed equipments using the above principle a nd method have many advantages such as small forming force, better filling for g ear teeth, high production precision, low surface roughness, and convenient patt erns drawing. The produced gears can satisfy the consumers demands and have been used in engineering, which show that the principle is feasible and the method i s reasonable, and lay the basis for "carburization- warmextrusion" forming techn ology of straight cylindrical gear. In order to study the mechanical behavior of carburized gradient materials, the annulus specimens with different carbon cont ents were obtained after carburization. By using the method of carburization- de carbonization, five specimens with different carbon content of 0.22%, 0.44%, 0.6 2%, 0.81% and 1.12% were acquired, so the purpose of dispersion was reached.With the help of computer simulation technology, how the specimens height affect the deformation homogeneous has been studied firstly by means of the annulus sp ecimens compression and results show that deformation homogeneous can be improve d by increasing relative height of the specimens and reducing friction. All the annulus specimens were chosen from the same 20CrMnTi bar, so the rest component are the same other than the carbon content after carburization. Therefore, the e xperimental results highlighted the effects of the carbon content on the macro a nd micro response of the materials and a new experimental method was provided fo r characteristic study of the nonuniform materials.The mechanical behavior and microstructure response of the carburized 20CrMnTisteel have been studied firstly. Experiments show that the flow stress has 3 bas ic characters with the change of the carbon content, i.e., the flow stress will fall at the temperature of 850℃, rise at the temperature of 690℃ and present t he complicated changing law at the temperature between 650℃ and 850℃ with the increase of the carbon content. 0.62% carbon content becomes a break point among the 3 kinds of the flow stress. The research of the microstructure shows that the change of the flow stress is t he macro response to the change of the microstructure. The monotonic decrease in the flow stress at higher temperature has a close relationship with the improve ment of the dynamic recrystallization rate caused by the increase of the carbon content. The rate of the dynamic recrystallization is obviously quickened when t he carbon content is up to 0.62% which is the break point of the flow stress, wh ile the monotone increase of the flow stress at lower temperature is the result of the micro structure changing from the heterogeneous structure of ferrite and austenite with low carbon to the heterogeneous structure of austenite and cement ite with high carbon. The grain fining mechanism of warm deformation, whose fini ng effect is more marked, is obviously different from that of hot deformation fo r the grain of the carburization 20CrMnTi.. The "necklace" dynamic recrystal, wh ich can fine grains from 16(m~20(m into (m~3(m, becomes the main...
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