SUS 321鋼のクリープ損傷様式とクリープ疲労相互作用との関連
1993 年 42 巻 472 号 p. 1-7
詳細
1993 年 42 巻 472 号 p. 1-7
In order to investigate the relationship between creep-fatigue interaction and creep damage mode of SUS 321 fine- and coarse-grained steels, the combined creep-fatigue loading tests were conducted. The creep damage, φc, and the fatigue damage, φf, which were accumulated till rupture in these tests were calculated using a linear life fraction damage rule. The φc vs. φf relation obtained was described by the following equation:
(φc-φc0)+α[(φc-φc0)(φf-φf0)]0.5+(φf-φf0)=1
where the values of φc0, φf0 and α depend on the creep damage mode corresponding to the creep loading condition in the combined creep-fatigue loading test. For the creep loading condition corresponding to transgranular fracture mode in creep test, the φc vs. φf relations of fine- and coarse-grained materials showed a convex form, but the value of φc0 was different between these two materials. The value of φc0 was dependent on cyclic hardening and softening behaviours of the materials under fatigue loading and on the sensibility of intergranular fracture of the materials tested. The φc vs. φf relation became φc+φf-1 under the fracture mode condition where the micro cracks were formed along the grain boundaries and the surface crack propagated through the micro cracks.
