奥氏体不锈钢深冷低温冲击试验方法研究

Study on impact test method of austenitic stainless steel at cryogenic temperature

以液氦作为冷源,结合G-M低温制冷机,实现-196^-269℃深冷温度环境,探索深冷低温冲击试验方法。结果表明,试样从低温环境中取出后置于大气环境中,温度出现快速回升。对于不同试验低温,可采用不同方法进行试验。试验温度T=4.2K时,可采用制冷机预冷+液氦持续喷淋的方法进行降温。试验温度10≤T<77K时,可采用玻璃容器填充气凝胶粉体对试样进行绝热保温处理;或根据试验温度以及回温测试结果,以一定的过冷温度补偿值保证试验温度。过冷温度补偿方法可满足常规冲击试验的要求,但需要相对较大的过冷温度补偿值;玻璃容器填充粉体包裹试样,可减缓试样温度回升,但对材料冲击吸收能量有一定影响,可用多试样冲击试验并进行修正以反映材料冲击韧性水平。

-196 ～ -269 ℃ cryogenic temperature environment was created by G- M refrigerator and liquid helium. The impact test method at cryogenic temperature was also explored in this paper. When the impact sample was taken out from cryogen- ic temperature to atmospheric environment, its temperature rose quickly. The test temperature was reached 4.2K by pre - cooling of G - M refrigerator and continued spraying of liquid helium. To ensure the test temperature of 10 ≤ T 〈 77K, the test sample was put in a glass container, which was filled with insulated powder. Or, a certain undercooling temperature value was set up during the cooling process. The value of undercooling temperature was determined by specific test temperature and rise of temper- ature. The method of undercooling compensation was applicable for conventional impact test, but the value of undercooling tem- perature compensation was large. When the sample was put in glass container filled with insulated powder, the glass container had good heat insulation effect. Meanwhile, the influence of container on impact energy absorption should not be ignored. The impact toughness level of material can be reflected by impact test of multiple samples.