Plastic Deformation Behavior And Hot Rolling Process Of Pure Molybdenum

Our country is rich in Mo resources as the greatest country with Mo resources in the world. Mo and its alloy are used as important materials in metallurgy, electric power equipment manufacturing, glassmaking, petrochemical industry, aerospace, national defense industry with a series of advantages, such as high melting point, high temperature strength, low expansion coefficient, low creep rate at high temperature, good thermal conductivity properties and so on. And molybdenum plate was the most widely applied as the end product of deep processing and raw material of stamping parts. However, rolling equipment was expected much and rolling process is difficult as a result of high strength, high deformation temperature, poor plasticity at low temperature of Mo and its alloy. Defects and other problems were often found in the rolling process of molybdenum plate, such as head cracking, layer, edge crack and so on. A new rolling processing technology was present in this paper for existing slab type and sintered density according to defects and other problems in the rolling process of molybdenum plate at home, aiming at plates with high performance and small anisotropy. The main research results are as follows:(1) Single-pass compression deformation behavior of pure Mo at high temperature was studied for four kinds of sintered density by thermal simulation experiment, and the influence of deformation parameter and sintered density on resistance to deformation was analyzed. Meanwhile dynamic softening behavior of pure Mo for various sintered density was also studied, and activation energy of dynamic recrystallization was counted as well as the higher accuracy model of resistance to deformation was built. Ultimately calculated by the model stress-strain curve and the measured stress-strain curves agree well prove that the model can better predict experimental steel high flow stress.(2) The double-compression tests for pure Mo were carried out, and the influence of deformation parameter on static recrystallization behavior for pure Mo was analyzed, and also the curve of static softening rate of Mo under different deformation conditions was drawn. The curve of static softening rate was present a curve of S similar to that of steel, especially at the temperature of 1400?. The perfect static recrystallization behavior was carried out at the temperature of above 1350?, and the recrystallization behavior was not present at the temperature of below 1200?. The static recrystallization activation energy of pure Mo was counted for the sintered density of 9.7-9.8 g/cm3, Qrex=455.3559 kJ/mol.(3) The microstructure of Mo was observed under different process, and the dynamic recrystallization behavior was analyzed under the condition of high temperature deformation. The results are as follows:The microstructure of Mo was greatly influenced by deformation rate and deformation temperature; The deformation rate of recrystallization increased with the rise of deformation temperature by stepwise rise;The conditions of dynamic recrystallization behavior is connected with the value of Z and the recrystallization occurs only when Z? Zc(for the sintered density of pure Mo's is 9.7-9.8g/cm3, Zc=8×1011s-1);A number of holes were found in the structure of pure Mo, some of whom were observed within the grain, and some were on the grain boundary. The phenomenon that the holes were located inside of the grain was caused by sintering process.(4) On the basis of the results for thermal simulation experiment, the foundation of setting rolling parameters was analyzed, and hot rolling technology for pure Mo were planned. The results show that initial hot rolling temperature is about 1400?, the rate of hot rolling is 0.6m/s, processing rate for hot rolling is generally 20%-30%.