Z.X. Wu and X.F. Sun ( Institute of Applied Mechanics
,
Southwest Jiaotong University
,
Chengdu 610031
,
China State Key Laboratory for Fatigue and Fracture of Materials
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang 110015
,
China)
金属学报(英文版)
The behavior of part-through and through short cmcks in single edge blunt notched specimens of a medium carbon steel was investigated by a replication method. It is found that the fatigue failure of these notched specitnensis caused mainly by the growth of short surface cracks originating from the sudece of notch root. More than 70% of the fatigue lofe is spent in the regimes in which short surface cracks initiate and propagate as part-through cracks before joining up to form a single through-thickness cmck. The effect of original crack profile which is forsned through the coalescence of multiple part-through cracks is the main reason causing the "anomalous" propagation behavior of the through-thickness cruck in its early stage.
关键词:
medium carbon steel
,
null
,
null
,
null
,
null
Q. Gao
,
X.J. Yang and G.Z. Kang(Department of Applied Mechanics and Engineering
,
Southwest Jiaotong University
,
Chengdu 610031
,
China )
金属学报(英文版)
An experimental investigation was cawted out of the cyclic saturated kinematic hardening of the solution treatment stainless steel 316L subjected to cyclic loading for seveml strain paths, such as uniaxial cycling, cireulan elliPtic, diamond, rectangular shapes. The evoluting tndectories of back stresses in deviatoric stress space were obtained, and the evolution of back stress mtes during cyclic saturuted loading was analyzed under the assumption that the yield sudece rudius at cyclic saturation is constant and the direction of plastic stmin rute coincides with the one of the out normal vector Of the yield sudece. Some significant results were obtained.
关键词:
stainless steel 316L
,
null
,
null
G.Z. Kang
,
Q. Gao
,
X.J.Yang and Y.F. Sun(Department of Applied Mechanics and Engineering
,
Southwest Jiaotong University
,
Chengdu 610031
,
China)
金属学报(英文版)
An experimental study was carried out of the cyclic behavior of U71Mn rail steel subjected to uniaxial strain and stress. The effects of cyclic struin amplitude, mean struin,strain loading rate and their histories on the strain cyclic characteristics were studied.Under the asymmetrical stress cycling, the effects of stress amplitude, mean stress,stress loading rate and their histories on the ratcheting were analyzed. The interaction between strain cycling and stress cycling was also discussed. It is shown that either the cyclic characteristics under strain cycling or the ratcheting under asymmetrical stress cycling depends not only on the cumnt loading state, but also on the previous loading history. Some significant results are obtained.
关键词:
cyclic plasticity
,
null
,
null
Q. Gao
,
Y.X. Zhao and L.X. Cai (Institute of Applied Mechanics
,
Southwest Jiaotong University
,
Chengdu 610031
,
China)
金属学报(英文版)
Based on the test results obtained from the single-step test and the incremental-step test at room temperature and 240℃, a probabilistic assessment of temperature effects on the cyclic stress-strum response and the fatigue life of 1Cr18Ni9Ti steel weld metal is performed. In orber to assess the temperature effect on cyclic stress amplitude where there is a scatter of the material cyclic constitution, a probabilistic assessment approach on the basis of probabilistic modified Ramberg-Osgood relations is introduced.The investigation shows that the cyclic stress amplitude and the scatter of cyclic stress amplitude data are decreased at 240℃. Similarly, from the consideration of the fatigue life scatter a probabilistic assessment of temperature effect on the fatigue life is suggested on the basis of probabilistic Langer S-N relations. The investigation shows that the crack initiation life is increased and the scatter of crack initiation life data is decreased at 240℃.
关键词:
1Cr_(18)Ni_9Ti stainless steel
,
null
,
null
,
null
,
null
