scholarly journals Comparison between Shot Peening, Cavitation Peening, and Laser Peening by Observation of Crack Initiation and Crack Growth in Stainless Steel

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 63 ◽  
Author(s):  
Hitoshi Soyama
Keyword(s):  
Stainless Steel ◽  
Laser Ablation ◽  
Fatigue Strength ◽  
Crack Initiation ◽  
Crack Growth ◽  
Shot Peening ◽  
Stress Test ◽  
Water Jet ◽  
Laser Peening ◽  
The Impact

The traditional technique used to modify the surface of a metallic material is shot peening; however, cavitation peening, a more recent technique in which shot is not used, was developed, and improvements in the fatigue strength of metallic materials were demonstrated. In order to compare the fatigue properties introduced by shot peening with those introduced by cavitation peening, crack initiation and crack growth in specimens of austenitic stainless steel (Japanese Industrial Standards JIS SUS316L) treated using these techniques were investigated. With conventional cavitation peening, cavitation is produced by injecting a high speed water jet into water. In the case of submerged laser peening, bubbles are generated using a pulsed laser after laser ablation, and the impact produced when the bubbles collapse is larger than that due to laser ablation. Thus, in this study, cavitation peening using a water jet and submerged laser peening were investigated. To clarify the mechanisms whereby the fatigue strength is improved by these peening techniques, crack initiation and crack growth in specimens with and without treatment were examined by means of a K-decreasing test, where K is the stress intensity factor, and using a constant applied stress test using a load controlled plane bending fatigue tester. It was found that the improvement in crack initiation and the reduction in crack growth were roughly in a linear relationship, even though the specimens were treated using different peening methods. The results presented here show that the fatigue strength of SUS316L treated by these peening techniques is closely related to the reduction in crack growth, rather than crack initiation.

Suppression of Fatigue Crack Growth in Austenite Stainless Steel by Cavitation Peening

2010 ◽  
Vol 452-453 ◽  
pp. 641-644 ◽  
Author(s):  
Osamu Takakuwa ◽  
Masaaki Nishikawa ◽  
Hitoshi Soyama
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Surface Modification ◽  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Compressive Residual Stress ◽  
Austenite Stainless Steel ◽  
The Impact

Cavitation normally causes severe damage in hydraulic machinery such as pumps and turbines by the impact produced by cavitation bubbles collapsing. Although cavitation is known as a factor of erosion, Soyama et al. succeeded in utilizing impacts of cavitation bubble collapsing for surface modification by controlling cavitating jet in the same way as shot peening. The local plastic deformation caused by cavitation impact enhances the fatigue strength of metallic materials, and the surface modification technique utilizing cavitation impact is called “cavitation peening (CP)”. It is well known that the peening improves fatigue strength by introducing compressive residual stress on the surface, but little attention has been paid to the behavior of fatigue crack growth of the material which was modified by CP. In the present study, the fatigue behavior of austenite stainless steel with and without CP was evaluated by a plate bending fatigue test, and the results revealed that the compressive residual stress introduced by CP suppresses fatigue crack growth rate by 70 % compared to that without CP.

Effect of Processing Layer on Fatigue Strength of Extruded AZ61 Magnesium Alloy

2013 ◽  
Vol 577-578 ◽  
pp. 429-432 ◽  
Author(s):  
Yukio Miyashita ◽  
Kyohei Kushihata ◽  
Toshifumi Kakiuchi ◽  
Mitsuhiro Kiyohara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Magnesium Alloy ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Crack Growth Resistance ◽  
Az61 Magnesium Alloy

Fatigue Property of an Extruded AZ61 Magnesium Alloy with the Processing Layer Introduced by Machining was Investigated. Rotating Bending Fatigue Tests were Carried out with the Specimen with and without the Processing Layer. According to Results of the Fatigue Tests, Fatigue Life Significantly Increased by Introducing the Processing Layer to the Specimen Surface. Fatigue Crack Initiation and Propagation Behaviors were Observed by Replication Technique during the Fatigue Test. Fatigue Crack Initiation Life of the Specimen with the Processing Layer was Slightly Longer than that of the Specimen without the Processing Layer. Higher Fatigue Crack Growth Resistance was also Observed when the Fatigue Crack was Growing in the Processing Layer in the Specimen with the Processing Layer. the Longer Fatigue Life Observed in the Fatigue Test in the Specimen with the Processing Layer could be Mainly due to the Higher Crack Growth Resistance. it is Speculated that the Fatigue Strength can be Controlled by Change in Condition of Machining Process. it could be Effective way in Industry to Improved Fatigue Strength only by the Cutting Process without Additional Surface Treatment Process.

scholarly journals Properties of the Fine Granular Area and Postulated Models for Its Formation during Very High Cycle Fatigue—A Review

2020 ◽  
Vol 10 (23) ◽  
pp. 8475
Author(s):  
Jan Patrick Sippel ◽  
Eberhard Kerscher
Keyword(s):  
Fatigue Strength ◽  
Crack Initiation ◽  
Crack Growth ◽  
High Performance ◽  
High Cycle Fatigue ◽  
The Other ◽  
Cycle Fatigue ◽  
Very High Cycle Fatigue ◽  
Open Questions ◽  
Very High

Understanding the mechanisms leading to very high cycle fatigue is necessary to make predictions about the behavior under various conditions and to ensure safe design over the whole lifetime of high-performance components. It is further vital for the development of possible measures to increase the very high cycle fatigue strength. This review therefore intends to give an overview of the properties of the fine granular area that have been observed so far. Furthermore, the existing models to describe the early crack initiation and crack growth within the very high cycle fatigue regime are outlined and the models are evaluated on the basis of the identified fine granular area properties. The aim is to provide an overview of the models that can already be considered refuted and to specify the respective open questions regarding the other individual models.

scholarly journals The impact of heat treatment and shot peening on the fatigue strength of 51CrV4 steel

2016 ◽  
Vol 2 ◽  
pp. 3330-3336 ◽  
Author(s):  
Andrzej Kubit ◽  
Magdalena Bucior ◽  
Władysław Zielecki ◽  
Feliks Stachowicz
Keyword(s):  
Heat Treatment ◽  
Fatigue Strength ◽  
Shot Peening ◽  
The Impact

Effect of Water Jet and Electroerosion Cutting on Fatigue Strength of Thick Al-Alloy Sheet

2010 ◽  
Vol 636-637 ◽  
pp. 1525-1530 ◽  
Author(s):  
Ivo Černý ◽  
Dagmar Mikulová
Keyword(s):  
Fatigue Strength ◽  
Crack Initiation ◽  
Fatigue Crack Initiation ◽  
Fatigue Tests ◽  
Alloy Sheet ◽  
Water Jet ◽  
Al Alloy ◽  
Water Jet Cutting ◽  
Deterioration Effect ◽  
Point Bend

Results of an experimental investigation of effects of two advanced technologies for materials cutting, namely water-jet and electroerosive cutting, respectively, are described. Water jet cutting, with abrasive particles and specific parameters, and electroerosive cutting were applied to an aircraft Al-alloy sheet Al 2124 T851 of a considerable thickness, namely 50.8 mm. Reference batch of specimens was manufactured using fine finishing milling. Surface quality of each of the cutting and machining technologies was evaluated and fatigue strength was investigated. Three point bend fatigue tests performed at constant stress amplitude showed a considerable deterioration effect of both technologies on fatigue strength. The damaging effect of both technologies was comparable. Fractographical analysis using scanning electron microscopy (SEM) showed fatigue crack initiation in numerous surface micro-notches occurring as a result of the cutting. In addition, the crack initiation was frequently accelerated by surface or subsurface fairly large particles of intermetallic phases. This mechanism also occurred with milling specimens.

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