Fracture Behavior of Aged CF8A Austenite Cast Stainless Steel Under Dynamic and Cyclic Loading Conditions

2017 ◽  
Author(s):  
Jin Weon Kim ◽  
Myung Rak Choi ◽  
Yun Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Cyclic Loading ◽  
Dynamic Loading ◽  
Thermal Aging ◽  
Fracture Behavior ◽  
Operating Temperature ◽  
Loading Conditions ◽  
Loading Effect ◽  
Loading Rates

This study conducted J-R fracture toughness tests using aged CF8A cast austenitic stainless steel (CASS) under dynamic and cyclic loading conditions at room temperature (RT) and 316°C and investigated the effect of seismic loading characteristics on the fracture behavior of age-related degraded material. For comparison, J-R fracture tests were also conducted on unaged CF8A CASS. CF8A CASS was made as a static casting, and it was aged thermally at 400°C for 175 days, which is equivalent to thermal aging at the operating temperature of nuclear power plants (NPPs) for 32 effective full power years (EFPYs). Monotonic J-R tests were conducted at both quasi-static and dynamic loading rates, and cyclic J-R tests were conducted at a quasi-static loading rate. The results showed that the fracture resistance of aged CF8A CASS under monotonic load was lower, by ∼35%, than that of unaged CF8A CASS, regardless of test temperatures and loading rates. The dynamic loading effect on fracture behavior was almost negligible for both unaged and aged CF8A CASSs at RT and 316°C. Cyclic loading reduced J-R fracture toughness of unaged CF8A CASS considerably at both test temperatures. Such a cyclic loading effect on fracture behavior was still observed from aged CF8A CASS. Thus, we conclude that the dynamic and cyclic loading effects on fracture behavior of CF8A CASS were not altered by thermal aging at the operating temperature of NPPs for 32 EFPYs.

J-R Fracture Toughness of Nuclear Piping Materials Under Excessive Seismic Loading Condition

2016 ◽  
Author(s):  
Jin Weon Kim ◽  
Myung Rak Choi ◽  
Sang Bong Lee ◽  
Yun Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Fracture Resistance ◽  
Cyclic Load ◽  
Fracture Behavior ◽  
Loading Rate ◽  
Seismic Loading ◽  
Monotonic Loading ◽  
Rate Effect ◽  
Loading Conditions

This study investigated the loading rate effect on the fracture resistance under cyclic loading conditions to clearly understand the fracture behavior of piping materials under excessive seismic conditions. J-R fracture toughness tests were conducted under monotonic and cyclic loading conditions at various displacement rates at room temperature (RT) and the operating temperature of nuclear power plants (NPPs), i.e., 316°C. SA508 Gr. 1a lo w-alloy steel (LAS) and SA312 TP316 stainless steel (SS) piping materials were used for the tests. The fracture resistance under a reversible cyclic load was considerably lower than that under monotonic load regardless of test temperature, material, and loading rate. Under both cyclic and monotonic loading conditions, the fracture behavior of SA312 TP316 SS was independent of the loading rate at both RT and 316°C. For SA508 Gr. 1a LAS, the loading rate effect on the fracture behavior was appreciable at 316°C under both cyclic and monotonic loading conditions. However, the loading rate effect diminished when the cyclic load ratio (R) was −1. Thus, it was recognized that the fracture behavior of piping materials, including seismic loading characteristics, can be evaluated when tested under a cyclic load of R = −1 at a quasi-static loading rate.

Fracture Toughness of Z3CN20.09M Cast Stainless Steel with Long-Term Thermal Aging

2017 ◽  
Vol 26 (9) ◽  
pp. 4442-4449 ◽  
Author(s):  
Weiwei Yu ◽  
Dunji Yu ◽  
Hongbo Gao ◽  
Fei Xue ◽  
Xu Chen
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Thermal Aging ◽  
Cast Stainless Steel

scholarly journals FDEM Modelling of Rock Fracture Process during Three-Point Bending Test under Quasistatic and Dynamic Loading Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Huaming An ◽  
Yushan Song ◽  
Hongyuan Liu
Keyword(s):  
Fracture Toughness ◽  
Dynamic Loading ◽  
Fracture Process ◽  
Loading Rate ◽  
Rock Fracture ◽  
Mesh Size ◽  
Bending Test ◽  
Loading Conditions ◽  
Three Point Bending ◽  
Dynamic Loading Conditions

A hybrid finite-discrete element method (FDEM) is proposed to model rock fracture initiation and propagation during a three-point bending test under quasistatic and dynamic loading conditions. Three fracture models have been implemented in the FDEM to model the transition from continuum to discontinuum through fracture and fragmentation. The loading rate effect on rock behaviour has been taken into account by the implementation of the relationship between the static and dynamic rock strengths derived from dynamic rock fracture experiments. The Brazilian tensile strength test has been modelled to calibrate the FDEM. The FDEM can well model the stress and fracture propagation and well show the stress distribution along the vertical diameter of the disc during the Brazilian tensile strength test. Then, FDEM is implemented to study the rock fracture process during three-point bending tests under quasistatic and dynamic loading conditions. The FDEM has well modelled the stress and fracture propagation and can obtain reasonable fracture toughness. After that, the effects of the loading rate on the rock strength and rock fracture toughness are discussed, and the mesh size and mesh orientation on the fracture patterns are also discussed. It is concluded that the FDEM can well model the rock fracture process by the implementation of the three fracture models. The FDEM can capture the loading rate effect on rock strength and rock fracture toughness. The FDEM is a valuable tool for studying the rock behaviour on the dynamic loading although the proposed method is sensitive to the mesh size and mesh orientation.

High-cycle and very-high-cycle fatigue behavior of a stainless steel for air-conditioning compressor valve plates

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xu Jia ◽  
Yang Ou Xiang ◽  
Hu Yuan Pei ◽  
Song Wei
Keyword(s):  
Stainless Steel ◽  
Cyclic Loading ◽  
Air Conditioning ◽  
High Cycle Fatigue ◽  
Loading Conditions ◽  
Cycle Fatigue ◽  
Content Type ◽  
Very High Cycle Fatigue ◽  
Load Characteristics ◽  
Very High

PurposeThe investigations could guide the structural design and fatigue life prediction of air-conditioning compressor valve plates.Design/methodology/approachThe High-Cycle Fatigue (HCF) and Very-High-Cycle Fatigue (VHCF) behaviors of stainless steel used for air-conditioning compressor valve plates were investigated. Monotonic and cyclic loading conditions were designed to explore the fatigue responses according to the load characteristics of the structure.FindingsThe crack initiation can be observed as the arc-shaped cracks at both sides of specimens and Y-shaped crack bifurcation in the specimens. Moreover, the middle section and the cracks at both ends are not connected to the surface of the specimen. The stress-life results of the materials under two directions (vertical and horizontal) were provided to examine the difference in fatigue strength.Originality/valueMonotonic and cyclic loading conditions were designed to explore the fatigue responses according to the load characteristics of the structure. Based on the experimental data, the results indicate that specimens under cyclic loading conditions could demonstrate better mechanical performance than static loadings.

Effects of thermal aging on the fracture toughness of cast stainless steel CF8

2019 ◽  
Vol 173 ◽  
pp. 45-54 ◽  
Author(s):  
David A. Collins ◽  
Emily L. Barkley ◽  
Timothy G. Lach ◽  
Thak Sang Byun
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Thermal Aging ◽  
Cast Stainless Steel
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