中等强度结构钢的韧性启裂和稳态扩展特性

Ductile Crack Initiation and Steady State Propagation of MediumStenetural Steel

研究了中等强度结构钢的韧性启裂,裂纹稳态扩展阻力和断裂过程中消耗的形变功。结果表明,具有相同组织状态的试样,随试样几何尺寸增加,启裂J积分值几乎没有变化,但J_i值由J_(i(e))和J_(i(p))共同构成转变为以J_(i(e))为主要构成;裂纹扩展阻力dJ/da由dJ-p/da为主要构成转变为由dJ_e/da和dJ-p/da共同构成。裂纹体在断裂过程中消耗的弹性功比例越来越大,抵抗裂纹继续扩展阻力明显降低。

The relationship among ductile crack initiation, resistanceof steady state propagation and deforation work absorbed in the fractureprocess for medium strength strutural steels are investigated. The experimental result show that for the same microstrieture material, the crackinitiation J-integral calue is few chang with the specimen size increasingbut Jiis composed of Ji(e) and Ji(p)when the specimen size smalleror only Ji(e) whenthe specimen size larger. The crack propagation resistance d J/dais. composed of dJ_p/daas the specimen size smaller or dJ_e/daand dJ_p/daif the specimen size larger. This lead to the increase of proportion of the elastic work absorbed in the fracture process andthe obvious decrease of the resistanee to crack steady state propagation