环境断裂的位错层次研究

INVESTIGATION OF ENVIRONMENT FRACTURE FROM DISLOCATION POINT OF F VIEW

从位错层次评述了断裂和环境断裂微裂纹的形核过程． 对于金属材料， 任何断裂过程（ 韧断， 本质脆断， 氢脆， 应力腐蚀， 液体金属脆） 均以位错发射、运动为先导， 只有局部塑性应变发展到临界条件，应力集中使局部应力等于原子键合力时才出现微裂纹的形核． 环境（ 氢， 腐蚀介质， 液体金属） 通过促进局部塑性变形引起低应力脆断． 不同环境促进位错发射。

Initiation of cracks during testing in air and in varions degradation environments hasbeen investigated from dislocation point of view . For metal materials ,any fracture process ,e . g .,ductile and brittle fracture tested in air ,hydrogen induced delayed failure ,stress corrosion crackingand liquid metal embrittlement,are preceded by dislocation emission and motion ,and only when dis location emission and motion developsinto a criticallevel,the localstress which equals to the cohe sive strength results in initiation of a microcrack . Hydrogen 、corrosion process itself during stresscorrosion cracking andliquid metal can facilitate dislocation emission and motion , resulting in variousenvironment brittle fracture .