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.

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 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.

Comparative study of the effective parameters on residual stress relaxation in welded aluminum plates under cyclic loading

2020 ◽  
Vol 21 (5) ◽  
pp. 505
Author(s):  
Yousef Ghaderi Dehkordi ◽  
Ali Pourkamali Anaraki ◽  
Amir Reza Shahani
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Relaxation ◽  
Stress Amplitude ◽  
Cyclic Plasticity ◽  
Mean Stress ◽  
Effective Parameters ◽  
Perfect Plasticity ◽  
Residual Stress Relaxation ◽  
Aluminum Plates

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accuracy of this analysis is verified through experiment. To study the plasticity effect on stress relaxation, two plasticity models are implemented: perfect plasticity and combined isotropic-kinematic hardening. Hence, cyclic plasticity characterization of the material is specified by low cycle fatigue tests. It is found that the perfect plasticity leads to greater stress relaxation. In order to propose an accurate model to compute the residual stress relaxation, the Taguchi L18 array with four 3-level factors and one 6-level is employed. Using statistical analysis, the order of factors based on their effect on stress relaxation is determined as mean stress, stress amplitude, initial residual stress, and number of cycles. In addition, the stress relaxation increases with an increase in mean stress and stress amplitude.

Effects of accelerator type on stress relaxation behavior and network structure of aged natural rubber/chloroprene rubber vulcanizates

2016 ◽  
Vol 49 (5) ◽  
pp. 381-396 ◽  
Author(s):  
Farzad A Nobari Azar ◽  
Murat Şen
Keyword(s):  
Stress Relaxation ◽  
Natural Rubber ◽  
Network Structure ◽  
Structural Changes ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Rubber Blends ◽  
Chloroprene Rubber ◽  
Weather Changes ◽  
Behavior Network

Natural rubber/chloroprene rubber (NR/CR) blends are among the commonly used rubber blends in industry and continuously are exposed to severe weather changes. To investigate the effects of accelerator type on the network structure and stress relaxation of unaged and aged NR/CE vulcanizates, tetramethyl thiuram disulfide, 2-mercaptobenzothiazole, and diphenyl guanidine accelerators have been chosen to represent fast, moderate, and slow accelerator groups, respectively. Three batches have been prepared with exactly the same components and mixing conditions differing only in accelerator type. Temperatures scanning stress relaxation and pulse nuclear magnetic resonance techniques have been used to reveal the structural changes of differently accelerated rubber blends before and after weathering. Nonoxidative thermal decomposition analyses have been carried out using a thermogravimetric analyzer. Results indicate that there is a strong interdependence between accelerator type and stress relaxation behavior, network structure, cross-linking density, and aging behavior of the blends. Accelerator type also affects decomposition energy of the blends.

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