With the further development of space industry and the continuous exploration of deep space, the performance requirements of cryogenic materials for spacecraft structures are further improved.
On the one hand, spacecraft structural materials must have sufficient strength and toughness as well as excellent thermal performance at low temperature. On the other hand, considering the complexity of the structure of spacecraft, the material must have good machinability.
Compared with the traditional low temperature materials, titanium alloy has a higher yield strength at low temperature, more than 3 times that of stainless steel, and its density is only 1/4~1/2 of stainless steel. In addition, titanium alloy also has a series of advantages such as low thermal conductivity, small coefficient of expansion and non-magnetic properties, so it is very suitable to be used as a new low-temperature material in the field of aerospace.
At present, cryogenic titanium alloy has been preliminarily applied in the field of liquid rocket engine, mainly used as structural materials such as hydrogen storage tank and hydrogen pump impeller of hydrogen and oxygen engine, which has greatly improved the thrust-weight ratio, working life and reliability of liquid rocket engine. The biggest problem in the application of low temperature titanium alloy lies in the significant decrease in elongation and fracture toughness of titanium alloy under low temperature environment, showing obvious low temperature brittleness. Therefore, how to reduce the low temperature brittleness of titanium alloy and improve the toughness and plasticity of titanium alloy under low temperature condition have become the top priority in the research of low temperature titanium alloy.
