scholarly journals Influence of Shot Peening Method on Rotating Bending Fatigue Limit for High Strength Steel

2010 ◽  
pp. 7-12 ◽  
Author(s):  
Katsuyuki MATSUI ◽  
Masayuki KOSHIMUNE ◽  
Koji TAKAHASHI ◽  
Kotoji ANDO
Keyword(s):  
Fatigue Limit ◽  
Shot Peening ◽  
High Strength Steel ◽  
High Strength ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

Improvement in Fatigue Limit by Shot Peening for High-Strength Steel Containing Crack-Like Surface Defect: Influence of Surface Crack Aspect Ratio

2013 ◽  
Author(s):  
Makiko Nakagawa ◽  
Koji Takahashi ◽  
Toshio Osada
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Aspect Ratio ◽  
Intensity Factor ◽  
Fatigue Limit ◽  
Shot Peening ◽  
High Strength Steel ◽  
High Strength ◽  
Bending Fatigue ◽  
Aspect Ratios

The effect of shot peening (SP) on the bending fatigue limit of high-strength steel (SUP9A) containing a semi-elliptical surface slit was investigated. SP was conducted on specimens containing a semi-elliptical surface slit with an aspect ratio (a/c) of 0.4, where a was the crack depth (a = 0.1, 0.2, and 0.3 mm) and c was half the surface length of the crack. Bending fatigue tests were carried out under a stress ratio R equal to 0. The results showed that the fatigue limit of the shot-peened specimens with slits having a depth of less than 0.2 mm was almost the same as that of the shot-peened specimens without slits. Meanwhile, some of the specimens fractured at the surface in areas other than the slit. Thus, the maximum depth of the slit that could be rendered harmless by SP was 0.2 mm. The maximum depths of cracks with various aspect ratios that could be rendered harmless by SP were predicted, assuming that the cracks were arrested when the apparent stress intensity factor at the slit tip was less than the threshold stress intensity factor of the material. The estimated values were in good agreement with the experimental values. A harmless crack assessment diagram was proposed based on this estimation method.

Improvement of Fatigue Behaviour of High Strength Aluminium Alloys by Fluidized Bed Peening (FBP)

2007 ◽  
Vol 344 ◽  
pp. 87-96 ◽  
Author(s):  
M. Barletta ◽  
F. Lambiase ◽  
Vincenzo Tagliaferri
Keyword(s):  
Fatigue Life ◽  
Fluidized Bed ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Maximum Amplitude ◽  
High Strength ◽  
Operational Parameters ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

This paper deals with a definition of a relatively novel technique to improve the fatigue behavior of high strength aluminum alloys, namely, Fluidized Bed Peening (FBP). Fatigue samples made from AA 6082 T6 alloy were chosen according to ASTM regulation about rotating bending fatigue test and, subsequently, treated by varying FBP operational parameters and fatigue testing conditions. First, a full factorial experimental plan was performed to assess the trend of number of cycles to rupture of fatigue samples varying among several experimental levels the factors peening time and maximum amplitude of alternating stress applied to fatigue samples during rotating bending fatigue tests. Second, design of experiment (DOE) technique was used to analyze the influence of FBP operational parameters on fatigue life of AA 6082 T6 alloy. Finally, ruptures of FB treated samples and untreated samples were discussed in order to evaluate the influence of operational parameters on the effectiveness of FBP process and to understand the leading process mechanisms. At any rate, the fatigue behavior of processed components was found to be significantly improved, thereby proving the suitability of FBP process as alternative mechanical technique to enhance fatigue life of components made from high strength aluminum alloy.

Improvement of Fatigue Strength of Aluminum Alloy by Cavitation Shotless Peening

2002 ◽  
Vol 124 (2) ◽  
pp. 135-139 ◽  
Author(s):  
Hitoshi Soyama ◽  
Kenichi Saito ◽  
Masumi Saka
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Strength ◽  
Shot Peening ◽  
High Speed ◽  
Bending Fatigue ◽  
Hydraulic Machinery ◽  
Bending Fatigue Test ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Cavitation Shotless Peening

Cavitation impact, which normally produces severe damage in hydraulic machinery, can be used to modify surfaces in the same way as shot peening. Cavitation impact enables the surface of a material to be peened without the use of shot, thus it is called cavitation shotless peening. As there are no solid body collisions occurring in this peening process, the roughness of the peened surface should be less than that produced by shot peening. This characteristic makes it suitable for peening soft metals. In order to demonstrate the improvement of the fatigue strength of aluminum alloy by this process, specimens were subjected to the process, and then tested in a rotating bending fatigue test. Cavitation impacts were produced and controlled by using a submerged high speed water jet with cavitation, i.e., a cavitating jet. It was revealed that the fatigue strength of an aluminum alloy specimen treated by this peening process was 50% stronger than that of a specimen without peening.

Improvement of Fatigue Limit by Shot Peening for High-Strength Steel Containing a Crack-Like Surface Defect: Influence of Stress Ratio

2012 ◽  
Author(s):  
Jun Yasuda ◽  
Koji Takahashi
Keyword(s):  
Fatigue Limit ◽  
Shot Peening ◽  
High Strength Steel ◽  
Stress Ratio ◽  
Structural Integrity ◽  
Fatigue Cracks ◽  
High Strength ◽  
Crack Size ◽  
Pressure Vessels ◽  
Circular Slit

It is well known that shot peening (SP) prevents the initiation and propagation of fatigue cracks and improves the fatigue limit of metals. It was recently reported that a surface crack can be rendered harmless by SP. Actual pressure vessels are generally operated under a positive stress ratio (R > 0). However, the effects of SP on the improvement of fatigue limits under R > 0 remain unclear. If these effects were clarified, the structural integrity of pressure vessels could be advanced. Thus, in this study, we investigated the influence of SP on fatigue limits and on the crack size that could be rendered harmless by SP under R > 0. High-strength steel specimens containing a semi-circular slit were subjected to SP. Bending fatigue tests were carried out under R = 0.4. The fatigue limits of the SP specimens increased 50∼100% compared with Non-SP specimens. Slits under 0.2 mm in depth were successfully rendered harmless by SP. The increasing ratios of the fatigue limit under R = 0.4 were lower than those under R = 0. However, the size of semi-circular slit that can be rendered harmless by SP remained the same. The size of the slit that can be rendered harmless can be predicted by calculating stress intensity factors.

Effect of Twice Quenching on Prior Austenite Grains and Rotating Bending Fatigue Cracks in SUJ2 Steel

2014 ◽  
Vol 620 ◽  
pp. 443-448 ◽  
Author(s):  
Koshiro Mizobe ◽  
Wakana Matsuda ◽  
Masayuki Matsushita ◽  
Takuya Shibukawa ◽  
Katsuyuki Kida
Keyword(s):  
Prior Austenite ◽  
Fatigue Cracks ◽  
High Strength ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Austenite Grain Size ◽  
Repeated Heating ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Rotating Bending

Martensitic high-carbon high-strength SUJ2 bearing steel has been widely used as a main alloy for rolling contact applications, and also in components under bending and tension-compression. In order to enhance the material’s strength, refining the prior austenite grain size through repeated-heating was investigated in our previous work. In this work, we observed the microstructure of twice quenched N-rich SUJ2 steel and performed their rotating bending fatigue tests. It was found that most of cracks on the fracture surface originated from Al2O3 inclusions.

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