Use of Cavitating Jet for Introducing Compressive Residual Stress

Abstract

In an attempt to strengthen the surface of materials, the potential of using a cavitating jet to form compressive residual stress has been investigated. Introducing compressive residual stress to a material surface provides improvement of the fatigue strength and resistance to stress corrosion cracking. In general, cavitation causes damage to hydraulic machinery. However, cavitation impact can be used to form compressive residual stress in the same way as shot peening. In the initial stage, when cavitation erosion progresses, only plastic deformation, without mass loss, takes place on the material surface. Thus, it is possible to form compressive residual stress without any damage by considering the intensity and exposure time of the cavitation attack. Cavitation is also induced by ultrasonic, high-speed water tunnel and high-speed submerged water jet, i.e., a cavitating jet. The great advantage of a cavitating jet is that the jet causes the cavitation wherever the cavitation impact is required. To obtain the optimum condition for the formation of compressive residual stress by using a cavitating jet, the residual stresses on stainless steel (JIS SUS304 and SUS316) and also copper (JIS C1100) have been examined by changing the exposure time of the cavitating jet. The in-plane normal stresses were measured in three different directions on the surface plane using the X-ray diffraction method, allowing for the principal stresses to be calculated. Both of the principal stresses are found changing from tension to compression within a 10 s exposure to the cavitating jet. The compressive residual stress as a result of the cavitating jet was found to be saturated after a certain time, but it starts decreasing, and finally, it approaches zero asymptotically. It could be verified in the present study that it was possible to form compressive residual stress by using a cavitating jet, and the optimum processing time could also be realized. The great difference between the water jet in water and air has also been shown in this regard. [S1087-1357(00)00501-3]

Engineering the residual stress state and microstructure of stainless steel with mechanical surface treatments

“…In WJCP, ultra-high pressure water jets are used to create a cloud of intense cavitation bubbles. Whether produced by flow or ultrasonically, cavitation introduces residual compressive stresses when the bubbles collapse on the surface producing a stress wave which plastically deforms the surface layers [5]. WJCP has been successfully applied to improve fatigue in aluminium alloys [6] and steels [7].…”

“…Other candidate treatments include ultrasonic impact treatment (UIT) [4] and water jet cavitation peening (WJCP), also known as cavitation shotless peening Fig. 1 Schematic description of the surface treatment process for ultrasonic impact treatment (UIT), laser shock peening (LSP), and water jet cavitation peening (WJCP) (CSP) [5][6][7] (see Fig. 1).…”

Cavitation Damage Behavior for 431 Stainless Steel by Hybrid Test in Sea Water

“…캐비테이션 피닝이란 표면 개질의 한 방법으로 숏 피닝(shot peening)과 함께 다양한 연구가 진행되어져 왔다 [15][16][17] . 특히 Lichtarowicz 은 캐비테이션 제트를 이용한 다양한 실험법을 제 시하였으며 18,19) , Soyama는 스테인리스강에 워터 캐 비테이션 제트를 분사하여 잔류응력을 개선하는 등 의 다양한 연구를 발표하였다 20,21) . …”

The Use of Cavitation Peening to Increase the Fatigue Strength of Duralumin Plates Containing Fastener Holes

“…The outer and inner diameters of the ring are about 60 mm and 15 mm, respectively. The cavitation clouds induced by the cavitating jet developed on the surface and then collapsed generating impacts, producing a ring pattern with the region at the center undamaged [23]. The sizes of the large plastically deformed pits are one or two mm in diameter.…”