scholarly journals Fracture Toughness Prediction under Compressive Residual Stress by Using a Stress-Distribution T-Scaling Method

Metals ◽  
2017 ◽  
Vol 8 (1) ◽  
pp. 6
Author(s):  
Toshiyuki Meshii ◽  
Kenichi Ishihara
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Stress Distribution ◽  
Compressive Residual Stress ◽  
Scaling Method

Application of the T-Scaling Method to Predict Fracture Toughness Under Compressive Residual Stress in the Transition Temperature Region

2018 ◽  
Author(s):  
Toshiyuki Meshii ◽  
Kenichi Ishihara
Keyword(s):  
Fracture Toughness ◽  
Residual Stress ◽  
Transition Temperature ◽  
Stress Distribution ◽  
Temperature Dependence ◽  
Temperature Region ◽  
Compressive Residual Stress ◽  
Crack Tip ◽  
Scaling Method ◽  
Crack Tip Stress

The fracture toughness Jc of a material in the ductile-to-brittle transition temperature region shows a test specimen thickness (TST) effect and temperature dependence, and apparently increases when a compressive residual stress is applied. Many models to explain these phenomena have been proposed that can also consider the large scatter of Jc. On the contrary, the authors have focused on the mean Jc and have demonstrated that the TST effect on Jc and temperature dependence of Jc are due to “the loss of the one-to-one correspondence between J and the crack-tip stress distribution” and that the “scaled” crack-tip stress distribution at fracture is independent of the TST effect on Jc or temperature. The T-scaling method was proposed and validated for this purpose. In this study, the fracture prediction of a specimen with compressive residual stress was performed using the T-scaling method, and its validity was confirmed for high-strength steel of 780-MPa class and 0.45 % carbon steel JIS S45C.

Heterogeneous Microstructure Effect on Residual Stress and Fatigue Crack Resistance in Dual-Phase Materials

2009 ◽  
Author(s):  
Masahito Mochizuki ◽  
Yoshiki Mikami
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Stress Distribution ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Residual Stress Distribution ◽  
Experimental Result ◽  
Microstructure Effect

The effect of transformation-induced microscopic residual stress on fatigue crack propagation behaviour of ferrite-martensite lamellar steel was discussed. Fatigue tests of prestrained and non-prestrained specimens were performed. Inflections and branches at ferrite-martensite boundaries were observed in the non-prestrained specimens. On the other hand, less inflections and branches were found in the prestrained specimens. The experimental results showed that the transformation induced microscopic residual stress has influence on the fatigue crack propagation behaviour. To estimate the microscopic residual stress distribution, a numerical simulation of microscopic residual stress induced by martensitic transformation was performed. The simulation showed that compressive residual stress was generated in martensite layer, and the result agree with the experimental result that inflections and branches were observed at ferrite-martensite boundaries. In addition, the change in the microscopic residual stress distribution by prestraining was also calculated to show the compressive residual stress changed to tensile by prestraining. This also agree with the experimental result of the observation of fatigue crack path.

Effect of Friction on Residual Stress Distribution Induced by Split Sleeve Cold Expansion Process

2020 ◽  
Author(s):  
Mithun K. Dey ◽  
Dave Kim ◽  
Hua Tan
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Compressive Residual Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Residual Stress Distribution ◽  
Expansion Process ◽  
Cold Expansion ◽  
Three Dimensional Finite Element

Abstract Residual Stress distribution and parametric influence of friction are studied for the split sleeve cold expanded holes in Al 2024 T351 alloy, by developing a three-dimensional finite element model of the process. Fastener holes in the alloy are necessary for the manufacturing process, but they create a potential area for stress concentration, which eventually leads to fatigue under cyclic loading. Beneficial compressive residual stress distribution as a result of the split sleeve cold expansion process provides retardation against crack initiation and propagation at the critical zones near hole edges. In this parametric study, the influence of friction between contact surfaces of the split sleeve and mandrel is numerically investigated. Hole reaming process after split sleeve cold expansion is often not discussed. Without this post-processing procedure, split sleeve cold expansion is incomplete in practice, and its purpose of providing better fatigue performance is invalidated. This study presents results and an overview of the significance of friction with the consideration of the postprocessing of split sleeve cold expansion. The numerical results show that with increasing friction coefficient, compressive residual stress reduces significantly at the mandrel entry side, which makes the hole edge more vulnerable to fatigue. The different aspects of finite element modeling approaches are also discussed to present the accuracy of the prediction. Experimental residual stress observation or visual validation is expensive and time-consuming. So better numerical prediction with the transparency of the analysis design can provide critical information on the process.

Mechanical properties and residual stress of HVOF sprayed nanostructured WC-17Co coatings

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040041
Author(s):  
Hairong Sun ◽  
Jinpeng Yu ◽  
Guoqing Gou ◽  
Wei Gao
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Residual Stress ◽  
Elastic Modulus ◽  
Tensile Stress ◽  
Compressive Residual Stress ◽  
Hvof Spray ◽  
Spray Technique ◽  
Oxygen Flame ◽  
Conventional Coating

Nanostructured WC-17Co, 2C-12Co coatings and conventional WC-17Co coating were prepared by High Velocity Oxygen Flame (HVOF) spray technique. The elastic modulus, fracture toughness and crack spread path were studied. The residual stress, different phases, microstructure from surface to the depth of coatings were also analyzed. While the nanostructured WC-12Co coating showed the highest elastic modulus, the nanostructured WC-17Co coating has the highest fracture toughness. The compressive residual stress of the nanostructured coatings was higher than the conventional coating. Both WC and W2C phases showed compressive residual stress, but Co6W6C phase showed tensile stress. The distribution of residual stress showed that the stress is the lowest at the surface and the highest close to the interface.

Application of Indirect Laser Peening to SUS304 Stainless Steel

2014 ◽  
Vol 783-786 ◽  
pp. 2316-2321
Author(s):  
Hiroshi Kawakami ◽  
Akiyoshi Kondo ◽  
Muneharu Kutsuna ◽  
Kiyotaka Saito ◽  
Hiroki Inoue ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Stress Distribution ◽  
Pulse Energy ◽  
Laser Power ◽  
Compressive Residual Stress ◽  
Residual Stress Distribution ◽  
Bending Test ◽  
Laser Peening

Indirect laser peening applied to the substrate of austenitic stainless steel with the sheet of similar material. Effects of indirect laser peening condition on the formation of the dimple and the residual stress were investigated in this paper. Shape of the dimple and distribution of the residual stress were measured by laser microscope and X-ray diffraction, respectively. It was observed by the microscope that clean substrate surface of as-received state kept after indirect laser peening because of protection by the sheet. However, fracture of sheet occurred slightly in high pulse energy condition. The diameter and the depth of the dimple by indirect laser peening increased with the increase of laser power. Efficiency of dimple formation decreased with the increase of pulse energy. Affective condition region of indirect laser peening with a combination between the substrate and the sheet of austenitic stainless steel may be limited below the laser power density of 10GW/cm2. It was confirmed that indirect laser peening induced compressive residual stress in the substrate. One of peak of compressive residual stress in residual stress distribution existed near the bottom of the dimple. Residual stress distribution which was produced by indirect laser peening may affect change of quasi bending modulus which was obtained by three-point bending test.

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