The thermal deformation of precision seamless steel tube the influence of the organization

Ultra high temperature resistance of precision seamless steel tube has been in advanced aircraft engine demand traction, its research has always been a titanium alloy, one of the most important areas are the most active branches, attaches great importance to by titanium alloy researchers around the world.

Because about alpha titanium alloy has good high temperature strength and close to the alpha + beta plasticity of titanium alloy, the most suitable for high temperature use, and has been dominant in the high temperature titanium alloys, currently in use and is developing, the most high temperature titanium alloy for alpha titanium alloy. The hot working is one of the effective methods to improve precision seamless steel tubes microstructure, the selection of hot working parameters on the microstructure of titanium alloy, processing performance and performance will have important influence.

BTi - 62421 - s almost alpha titanium alloy titanium alloy as a new type of high temperature, there is no research data of its formability at room temperature. Based on BTi - 62421 - s titanium alloy as the research object, study and grasp the deformation parameters (deformation temperature, deformation degree) is the influence law of mechanical properties of titanium alloy, and seek the optimum comprehensive mechanical properties of titanium alloy the optimal deformation parameters.

Experimental materials for precision seamless steel tubes, the main alloy elements (mass fraction, %) : 5.8 ~ 7.0, and 1.5 ~ 2.5 Sn, Zr of 3.5 ~ 4.5, 0.3 ~ 1.3 Mo, Nb of 1.5 ~ 2.5, 0.1 ~ 0.4 Si, impurity < 1, allowance for Ti. Supply status to hot isostatic pressing. BTi - 62421 - s for nearly alpha titanium alloy, titanium alloy to use temperature 550 , the phase transition point 1010 .

To eliminate precision seamless steel tube surface fine grain area, the negative effect on the experimental results, in the original casting surface of the six resection to 10 mm, sampling, made into standard samples. Deformation temperature is 850  and different deformation degree (40%, 50%, 60%, 70%, 80%) and the deformation of 40%, the different deformation temperature (850 , 900 , 950 , 1000 , 1050 ), isothermal plane compression tests of two groups. The compressed sample hardness and mechanical tensile test.

The mechanical properties of precision seamless steel tube show regular change along with the change of deformation parameters: within a certain range, the deformation increases, the comprehensive mechanics performance of the material becomes optimal; Deformation temperature will get different organization and performance, below the phase transition temperature deformation of the organizational performance is superior to the above the phase transition point temperature deformation.

Precision seamless steel tube organizations and grain size after deformation is the main cause of the change of the mechanical properties. Organization for the fine equiaxed after deformation, can get better mechanical properties. When the deformation temperature is 900 ~ 950 , the deformation is 60% ~ 70% for the organization and has a better mechanical properties, thus put forward the deformation parameters of precision seamless steel tube for: deformation temperature 950 , the deformation of 60%.