Peening

About: Peening is a research topic. Over the lifetime, 5538 publications have been published within this topic receiving 73073 citations.

Assessment of Tensile Residual Stress Mitigation in Alloy 22 Welds Due to Laser Peening

Abstract: This paper examines the effects of laser peening on Alloy 22 (UNS N06022), which is the proposed material for use as the outer layer on the spent-fuel nuclear waste canisters to be stored at Yucca Mountain. Stress corrosion cracking (SCC) is a primary concern in the design of these canisters because tensile residual stresses will be left behind by the closure weld. Alloy 22 is a nickel-based stainless steel that is particularly resistant to corrosion, however, there is a chance that stress corrosion cracking could develop given the right environmental conditions. Laser peening is an emerging surface treatment technology that has been identified as an effective tool for mitigating tensile redisual stresses in the storage canisters. The results of laser-peening experiments on Alloy 22 base material and a sample 33 mm thick double-V groove butt-weld made with gas tungsten arc welding (GTAW) are presented. Residual stress profiles were measured in Alloy 22 base material using the slitting method (also known as the crack-compliance method), and a full 2D map of longitudinal residual stress was measured in the sample welds using the contour method. Laser peening was found to produce compressive residual stress to a depth of 3.8 mm in 20 mm thick base material coupons. The depth of compressive residual stress was found to have a significant dependence on the number of peening layers and a slight dependence on the level of irradiance. Additionally, laser peening produced compressive residual stresses to a depth of 4.3 mm in the 33 mm thick weld at the center of the weld bead where high levels of tensile stress were initially present.@DOI: 10.1115/1.1789957#

Comparison of Ultrasonic Impact Treatment (UIT) and Other Fatigue Life Improvement Methods

Abstract: Considerable recent attention has been paid to investigating the efficiency of ultrasonic impact treatment (UIT) as one of the post-weld methods for improving the reliability and fatigue lives of welded joints. Investigations were carried out at different times in Russia, Ukraine, France, Japan, Norway, Sweden and the USA. The work under review is intended to determine and study the benefits of UIT according to the IIW Collaborative Test Program on Improvement Methods, by comparison with well-known methods for increasing the fatigue strengths of welded joints. The paper presents comparative fatigue test results for welded specimens in the as-welded condition and specimens treated by hammer peening, shot peening, TIG dressing, ultrasonic impact treatment and a combination of TIG dressing and ultrasonic impact treatment. The specimens were fabricated from structural steel (SSAB Weldox 420). It is shown that, by correctly choosing the conditions, UIT can produce the highest improvement in fatigue life.

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

Abstract: Four mechanical surface treatments have been considered for the application to austenitic stainless steel structures. Shot peening (SP), laser shock peening (LSP), ultrasonic impact treatment (UIT) and water jet cavitation peening (WJCP), also known as cavitation shotless peening (CSP), have been applied to 8 mm thick Type 304 austenitic stainless steel coupons. This study considers the merits of each of these mechanical surface treatments in terms of their effect on the surface roughness, microstructure, level of plastic work and through thickness residual stress distribution. Microstructural studies have revealed the formation of martensite close to the treated surface for each process. Residual stress measurements in the samples show compressive stresses to a significantly greater depth for the LSP, UIT and WJCP samples compared to the more conventional SP treated sample.