Based on the experiments did by B.K.Parida and T.Nicholas [1], the fatigue crack propagation rate of TiAl alloy under different stress ratios had been tested in order to find out the role of stress ratio and to derive an improved fatigue crack propagation formula for region II(the expansion region) according to Paris formula and to calculate the specific values of the constants in the formula. The experimental results reveal that stress ratio has a significant influence on fatigue crack growth rate.

Based on the fatigue crack propagation experiments did by A.-L. Gloanec et al., the fatigue crack propagation rates of TiAl alloy of two processing routes, namely casting and PM, and stress ratios had been tested, in order to find out the effects of microstructure and stress ratio. An improved fatigue crack propagation formula for region Ⅱ (the expansion region) was derived according to Paris formula. The specific values of the constants in the formula were calculated. Fatigue crack propagation resistance of nearly fully lamellar microstructure is superior to that of equiaxed γ grain. The experimental results present that both microstructure and stress ratio has a significant influence on fatigue crack growth rate.

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Introduces the working principle of capping machine, the defects caused by the deficiency of the actual production situation of working medium pressure covermachine and its compensation spring, redesign compensation spring, and the design, the factors should be considered in a simple discussion.

With times of tensile tests, the tensile behavior of a kind of stainless steel at room temperature was determined. According to the results of tensile tests, some parameters of mechanical properties of the stainless steel can be obtained. Fatigue crack expansion of COD stainless steel specimens at room temperature can be simulated with the finite element software extensions.