scholarly journals Stress Relaxation Behavior of Cavitation-Processed Cr–Mo Steel and Ni–Cr–Mo Steel

2019 ◽  
Vol 9 (2) ◽  
pp. 299
Author(s):  
Kumiko Tanaka ◽  
Daichi Shimonishi ◽  
Daisuke Nakagawa ◽  
Masataka Ijiri ◽  
Toshihiko Yoshimura
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
High Pressures ◽  
Relaxation Behavior ◽  
Material Surface ◽  
Stress Relaxation Behavior ◽  
Gas Atmosphere ◽  
New Processing

Cr–Mo steel and Ni–Cr–Mo steel have higher strength and hardness than carbon steel, and they are occasionally used in harsh environments where high temperatures and high pressures are simultaneously applied in an oxidizing gas atmosphere. In general, in order to improve the fatigue strength of a material, it is important to impart compressive residual stress to the material surface to improve crack resistance and corrosion resistance. Conventionally, the most famous technique for imparting compressive residual stress by surface modification of a material is shot peening processing. However, in shot peening processing, there is concern that particles adhere to the surface of the material or the surface of the material becomes rough. Therefore, in this study high temperature and high-pressure cavitation was applied and the material surface was processed at the time of collapse. A theoretical and experimental study on a new processing method giving compressive residual stress was carried out. In the present study, we will report stress relaxation behavior due to the heat of cavitation in processed Cr–Mo steel and Ni–Cr–Mo steel.

Stress Relaxation Behavior in PWHT of Welded Components

2011 ◽  
Author(s):  
Jinmiao Zhang ◽  
Pingsha Dong ◽  
Shaopin Song
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Dominant Role ◽  
Relaxation Mechanism ◽  
Post Weld Heat Treatment ◽  
Relaxation Behavior ◽  
Material Strength ◽  
Fundamental Issue ◽  
Stress Relaxation Behavior ◽  
Weld Residual Stress

This paper is focused on the discussion of weld residual stress relaxation in a uniform post weld heat treatment (PWHT). In particular, the paper is attempted to address a fundamental issue related to the PWHT stress relaxation behavior, i.e., what is the dominant stress relaxation mechanism in PWHT? Is it due to creep or material strength reduction at elevated temperature? The paper starts with a simplified 3-bar weld model to demonstrate how weld residual stress is developed and relaxed. It then follows with an example of thick section narrow groove weld to highlight the results and conclusions. The results clearly indicate that creep mechanism plays a dominant role in the stress relaxation of PWHT. Several other important observations related to the stress relaxation are also summarized.

Mechanism for stress relaxation behavior of the residual stress improving treatments with water jet peening and buffing

2020 ◽  
Vol 796 ◽  
pp. 140221
Author(s):  
Lina Yu ◽  
Kazuyoshi Saida ◽  
Hideki Araki ◽  
Kazuki Sugita ◽  
Masataka Mizuno ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Water Jet ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior

Fabrication, Stress Relaxation Behavior and Bioactivity Evaluation of HA-316L Asymmetrical Functionally Gradient Biomaterial

2011 ◽  
Vol 239-242 ◽  
pp. 1049-1057
Author(s):  
Jian Peng Zou
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Tensile Stress ◽  
Hot Pressing ◽  
Relaxation Effect ◽  
Relaxation Behavior ◽  
Gradient Structure ◽  
Stress Relaxation Behavior ◽  
Functionally Gradient ◽  
Component Design

HA/316L powder asymmetrical functionally gradient biomaterial (FGM) with varying 316L content at 100vol%, 80vol%, 60vol%, 40vol%, 20vol%, 0vol% throughout the thickness of the samples was successfully fabricated by hot pressing(HP) technique. The stress relaxation behavior indicates that gradient structure of the asymmetrical HA/316L FGM has prominent relaxation effect of thermal residual stress. The largest stress in the FGM is 246.13 MPa, which is belonging to tensile stress and at 316L-80vol%HA/ 316L interface. The surfaces of HA/316L FGM are covered with a layer of bone-like apatite after soaking in dynamic SBF, and the apatite increases with the increase of HA content. It reveals that HA/316L FGM with good bioactivity can be obtained with reasonable component design of gradient layers.

Study on the Improvement of Fatigue Crack Growth Performance of 6061-T6 Aluminum Alloy Subject to Laser Shot Peening

2011 ◽  
Vol 464 ◽  
pp. 391-394 ◽  
Author(s):  
Cheng Dong Wang ◽  
Jian Zhong Zhou ◽  
Shu Huang ◽  
X.D. Yang ◽  
Z.C. Xu ◽  
...  
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Crack Growth ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Compact Tension ◽  
Crack Size ◽  
Laser Shot ◽  
Material Surface ◽  
Residual Stress Field

In order to enhance mechanical property and restrain crack growth of 6061-T6 aluminum alloy, laser shot peening (LSP) was employed to induce compressive residual stress and plastic deformation on the surface of metal. The FEA code ABAQUS and MSC. Fatigue were used to simulate crack growth of Compact tension (CT) specimens treated by LSP. The numerical simulation results showed that LSP can effectively inhibit the crack growth, decrease the crack growth rate as well as increase the final crack size, and as a consequence, fatigue life was extended. Adding peening times could get deeper compressive residual stress field which strengthen material surface and restrain crack growth, but the fatigue stress intensity factor threshold decreases.

scholarly journals Small–Scale Experimental Investigation of Fatigue Performance Improvement of Ship Hatch Corner with Shot Peening Treatments by Considering Residual Stress Relaxation

2021 ◽  
Vol 9 (4) ◽  
pp. 419
Author(s):  
Jin Gan ◽  
Zi’ang Gao ◽  
Yiwen Wang ◽  
Zhou Wang ◽  
Weiguo Wu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Life ◽  
Stress Relaxation ◽  
Stress Field ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Fatigue Performance ◽  
Residual Stress Field ◽  
Residual Stress Relaxation

Ship hatch corner is a common structure in a ship and its fatigue problem has always been one of the focuses in ship engineering due to the long–term high–stress concentration state during the ship’s life. For investigating the fatigue life improvement of the ship hatch corner under different shot peening (SP) treatments, a series of fatigue tests, residual stress and surface topography measurements were conducted for SP specimens. Furthermore, the distributions of the surface residual stress are measured with varying numbers of cyclic loads, investigating the residual stress relaxation during cyclic loading. The results show that no matter which SP process parameters are used, the fatigue lives of the shot–peened ship hatch corner specimens are longer than those at unpeened specimens. The relaxation rate of the residual stress mainly depends on the maximum compressive residual stress (σRSmax) and the depth of the maximum compressive residual stress (δmax). The larger the values of σRSmax and δmax, the slower the relaxation rates of the residual stress field. The results imply that the effect of residual stress field and surface roughness should be considered comprehensively to improve the fatigue life of the ship hatch corner with SP treatment. The increase in peening intensity (PI) within a certain range can increase the depth of the compressive residual stress field (CRSF), so the fatigue performance of the ship hatch corner is improved. Once the PI exceeds a certain value, the surface damage caused by the increase in surface roughness will not be offset by the CRSF and the fatigue life cannot be improved optimally. This research provides an approach of fatigue performance enhancement for ship hatch corners in engineering application.

scholarly journals The Effect of Specimen Dimension on Residual Stress Relaxation of the Weldments

2014 ◽  
Vol 996 ◽  
pp. 820-826 ◽  
Author(s):  
Zhong Yuan Qian ◽  
Scott Chumbley ◽  
Eric Johnson
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Relaxation ◽  
Finite Element Modeling ◽  
Empirical Model ◽  
Stress Measurement ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
X Ray ◽  
Residual Stress Relaxation

The purpose of this study is to evaluate the residual stress relaxation behavior in weldments. The stress relaxation is studied while successively reducing the size of weld specimens. Finite-element modeling was used to simulate the stress relaxation, and then an empirical model was derived based on the experimental and modeling results. The results of this study shall encourage industry users to utilize more plentiful conventional X-ray diffractometers for residual stress measurement of large weld components.

scholarly journals Residual-stress relaxation mechanism and model description of 5052H32 Al alloy spun ellipsoidal heads during annealing treatment

2021 ◽  
Author(s):  
Yong-Cheng Lin ◽  
Jiang-Shan Zhu ◽  
Jia-Yang Chen ◽  
Jun-Quan Wang
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Annealing Temperature ◽  
Relaxation Behavior ◽  
Advanced Technology ◽  
Avrami Equation ◽  
Model Description ◽  
Al Alloy ◽  
Stress Relaxation Behavior ◽  
Residual Stress Relaxation

AbstractMarginal-restraint mandrel-free spinning is an advanced technology for manufacturing ellipsoidal heads with large diameter-thickness ratios. Nevertheless, the spinning-induced residual stress, which greatly influences the in-service performance of spun heads, should be removed. In this study, the effects of annealing on the residual-stress relaxation behavior of 5052H32 aluminum alloy spun heads were investigated. It is found that the residual stress first rapidly decreases and then remains steady with the increase in annealing time at the tested annealing temperatures. The relaxation of the residual stress becomes increasingly obvious with the increase in annealing temperature. When the annealing temperature is less than 220 °C, there are no obvious changes in grain size. Moreover, the spinning-induced dislocations are consumed by the static recovery behavior, which decreases the residual stress during annealing. When the annealing temperature is approximately 300 °C, the broken grains transform into equiaxed grains. In addition, static recrystallization and recovery behaviors occur simultaneously to promote the relaxation of the residual stress. Considering the different stress relaxation mechanisms, a model based on the Zener-Wert-Avrami equation was established to predict the residual-stress relaxation behavior. Finally, the optimized annealing temperature and time were approximately 300 °C and 30 min, respectively.

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