scholarly journals The Effect of the Static Load in the UNSM Process on the Corrosion Properties of Alloy 600

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3165 ◽  
Author(s):  
Ki Tae Kim ◽  
Young Sik Kim
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Static Load ◽  
Impedance Measurement ◽  
Optical Microscope ◽  
Alloy 600 ◽  
Corrosion Properties ◽  
Cyclic Polarization ◽  
Static Loads ◽  
Compressive Residual Stresses

To suppress stress corrosion-cracking, compressive residual stresses, such as shot peening, laser peening, water jet peening, ultrasonic peening, and ultrasonic nanocrystal surface modification (UNSM) are utilized. However, among the numerous techniques, there is little research about the corrosion effect of detailed conditions, such as static load or amplitude in UNSM. A study on UNSM among various techniques of adding compressive residual stress to Alloy 600 was conducted. The focus of this study was on the effect of the static load in UNSM on the corrosion properties of Alloy 600. Microstructure analysis was conducted using an optical microscope (OM), a scanning electron microscope (SEM), and electron backscattering diffraction (EBSD), while compressive residual stress was measured using a nano-indentation technique. A cyclic polarization test and the AC (Alternating Current)-impedance measurement were both used to analyze the corrosion properties. An increase in static load under critical static load enhanced the grain boundary diffusion, consequently strengthened the passive film, and facilitated the surface diffusion, thereby improving the passivation of Alloy 600. However, higher static loads over the critical value can lead to an increase in the friction between the striking tip and the surface, thereby creating an overlapped wave, which reduces the corrosion properties.

Long Term Stability Evaluation of Stress Improvement Effect on Ni-Based Alloy Welds by Various Residual Stress Improvement Methods

2021 ◽  
Vol 1016 ◽  
pp. 819-825
Author(s):  
Li Na Yu ◽  
Kazuyoshi Saida ◽  
Masahito Mochizuki ◽  
Kazutoshi Nishimoto ◽  
Naoki Chigusa
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Stress Relaxation ◽  
Compressive Residual Stress ◽  
Alloy 600 ◽  
Pressurized Water ◽  
Residual Stress Relaxation ◽  
Temperature Environment ◽  
Water Reactors ◽  
High Temperature Environment

Stress corrosion cracking (SCC) is one of serious aging degradation problems for the Alloy 600 components of pressurized water reactors (PWRs). In order to prevent SCC, various methods such as water jet peening (WJP), laser peening (LP), surface polishing have been used to introduce compressive stresses at the surfaces of the PWR components. However, it has been reported that such compressive residual stress introduced by these methods might be relaxed during the practical operation, because of high temperature environment. In this study, the hardness reduction behavior of the Alloy 600 processed by LP, Buff and WJP in the thermal aging process has been investigated to estimate the stability of the residual stress improving effect by each method, based on the fact that there is a correlation between the compressive residual stress relaxation and the decrease of hardness. The behavior of the residual stress relaxation in the processed materials in the high temperature environment has been discussed with kinetic analysis.

Effects of Laser Shock Processing on Corrosion Properties of 304 Stainless Steel

2010 ◽  
Vol 426-427 ◽  
pp. 109-113
Author(s):  
De Jun Kong ◽  
Hong Miao ◽  
A.P. Hu
Keyword(s):  
Aqueous Solution ◽  
Residual Stress ◽  
Stainless Steel ◽  
Stress Corrosion ◽  
Compressive Residual Stress ◽  
Hardened Layer ◽  
304 Stainless Steel ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Corrosion Properties

The surface of 304 stainless steel was processed by laser shock wave, its surface micro-structures were observed with SEM, and residual stresses on its surface were measured with X-ray diffraction (XRD) stress tester, and the production mechanism of residual stress was analyzed. The experiment of stress corrosion in 25% NaCl aqueous solution was finished, the crack sensitivity of stress corrosion in NaCl aqueous solution was researched, and the effects of LSP on stress corrosion resistance were analyzed. The results shown that the refined hardened-layer is acquired on the surface of 304 stainless steel by LSP, and compressive residual stress has greatly increased, which improve availably the performances of stress corrosion resistant. The time of appearing cracks is inverse ratio with compressive residual stress, and LSP decreases effectively its stress corrosion cracks.

scholarly journals Effect of Different Manufacturing Process Steps on the Final Residual Stress Depth Profile along the Process Chain of Autofrettaged Thick-Walled-Cylinders

2014 ◽  
Vol 996 ◽  
pp. 676-681 ◽  
Author(s):  
Horst Brünnet ◽  
Michael Hofmann ◽  
Nataliya Lyubenova ◽  
Dirk Bähre
Keyword(s):  
Residual Stress ◽  
Depth Profile ◽  
Manufacturing Process ◽  
Compressive Residual Stress ◽  
Design Tool ◽  
Process Chain ◽  
Technical Process ◽  
Depth Profiles ◽  
The Impact ◽  
Compressive Residual Stresses

Selectively induced compressive residual stress depth profiles are gaining increasing importance as design tool for internally pressurized components. Hydraulic Autofrettage (AF) is a well-known manufacturing process to induce pronounced compressive residual stresses. However, AF does not stand alone in the technical process chain. In this paper, results from neutron diffraction experiments performed on thick-walled cylinders are presented and compared to finite-element simulations with Abaqus/CAE. The impact on the final residual stress depth profile after pre-machining, Autofrettage and post-machining is discussed.

scholarly journals Comparative study: Impact of Ball burnishing and shot peening Process on Aluminium 2024 alloy

2021 ◽  
Vol 23 (08) ◽  
pp. 1768-1775
Author(s):  
◽  
Mahendra Kumara C ◽  
D. Shivalingappa ◽  
Prema. S ◽  
◽  
...  
Keyword(s):  
Residual Stress ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Fluid Pressure ◽  
Ball Burnishing ◽  
Hydraulic Unit ◽  
2024 Alloy ◽  
Burnishing Process ◽  
Aeroengine Components ◽  
Compressive Residual Stresses

Compressive residual stress is the major aspect in the extension of the fatigue life of aeroengine components. In this study, a modified burnishing surface treatment and conventional shot peening process was used was proposed to improve surface integrity characteristics such as surface finish, hardness, and stable, advantageous compressive residual stress in turned Cylindrical Aluminum 2024Specimen. In burnishing process, a rolling rigid spherical HSS ball is pressed across an Aluminum 2024Specimen under definite fluid pressure generated by the hydraulic unit and also shot peening was carried out at a shot velocity of 300 m/s. This research examined the effect of burnishing treatment and shot peening process on beneficial compressive residual stresses.

Microscale Modeling to Study Shot Peening Effects on Aluminum Alloy

2016 ◽  
Author(s):  
H. Bae ◽  
M. Ramulu ◽  
A. Hossain
Keyword(s):  
Residual Stress ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Single Shot ◽  
Impact Model ◽  
Multiple Impacts ◽  
Residual Stress Field ◽  
Multiple Impact ◽  
Microscale Modeling ◽  
Compressive Residual Stresses

Shot peening is a cold working process used to produce a compressive residual stress to modify mechanical properties of metals. It causes impacting a surface with shots with significant force to create plastic deformation. The compressive residual stresses developed by shot peening process helps to avoid the propagation of micro-cracks exist in surface. Shot peening process is often used in aircraft industries to relieve tensile stresses built up in the grinding process, and replace them with beneficial compressive residual stresses. Shot peening has been developed to increase the fatigue strength of metallic parts. Compressive residual stress and surface hardening induced by shot peening process are found beneficial to increase the fatigue life and the resistance to stress corrosion cracking within the metallic component. Even though shot peening has been used for more than 50 years, a review of published papers indicates a lack of studies in numerical modeling. In particular, the effect of complex shot peening process to predict the target material responds to the multiple impacts of shots is not fully revealed. Most studies have investigated the fundamental mechanism and characteristics of fatigue improvement by single shot peening, and have studied the compressive residual stress induced by single normal impact on the surface of the specimen. However, single impact model is appropriate and efficient for sensitivity studies, local plastic effect, and indentation estimation. It is well known that the residual stress by single shot model is not suitable for practical use. The residual stress field from multi impacts is the resultant sum of all the fields by repeated and progressive impacts. It is not feasible to extrapolate results from the single impact model to a practical shot peening process with multiple impacts. Therefore, this research attempts to conduct a microscale modeling to study the shot peening effects of aluminum alloy responds to single and multiple impacts. First, a single shot impact model, representing single shot peening process, has been developed for the estimation of indentations at different velocities. The numerical simulations has been performed with the finite element software code LS-DYNA. The validations of the numerical simulations has been made from experimentally measured surface roughness data. Once the finite element code of single shot peening model is validated, additional numerical models are developed to simulate multiple shot peening process, using multiple impact shots. The multiple impact model are developed for the estimation of the residual stress field.

Fatigue Properties of Nitride Cr-Mo Steel with CrN Thin Film Deposited by Aip Method

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1554-1559 ◽  
Author(s):  
Daisuke Yonekura ◽  
Atsushi Tsukuda ◽  
Ri Ichi Murakami ◽  
Koji Hanaguri
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
Fatigue Strength ◽  
Film Thickness ◽  
Compressive Residual Stress ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Three Point Bending

In this study, we selected the nitride Cr-Mo Steel SCM435 as the substrate. Attention was focussed on the effect of film thickness. The Arc Ion Plating was performed using Cr cathode and N2 gas. The specimens were prepared for the film thickness 6, 12 and 18μm The three point bending fatigue tests were performed at room temperature in a laboratory environment. After the fatigue test, crack initiation sites were examined by using an optical microscope and a scanning electron microscope. The results obtained were as follows: (1) A high compressive residual stress generated in the film, and the compressive residual stress of 12μm film thickness was the greatest. (2) The fatigue strength of coated specimens for thin film was slightly lower than for substrate. (3) The film thickness hardly affected the fatigue strength of coated specimens.

Investigation on Residual Stress and Flank Wear of Tool Insert in Hard Turning of Chrome Plated EN24 Substrate

2014 ◽  
Vol 4 (2) ◽  
pp. 14-28
Author(s):  
K.N. Mohandas ◽  
C.S. Ramesh ◽  
Eshwara Prasad Koorapati ◽  
N. Balashanmugam
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Compressive Residual Stress ◽  
Hard Turning ◽  
Flank Wear ◽  
Residual Stress Distribution ◽  
A Value ◽  
Cutting Inserts ◽  
Hard Chrome ◽  
Compressive Residual Stresses

In the present investigation the hard chrome plated surfaces were hard turned using PcBN cutting inserts. The results of the experiment showed that the hard turning can be applied for the finish machining of chrome plated surfaces. The influence of hard turning was observed when it was tested for residual stress distribution. The results disclosed that the chrome plating technhique has induced the compressive residual stress of -355.9MPa in the workpieces. These compressive residual stresses increased to a value of -723.3MPa after hard turning the chrome plated surfaces. But with worn out insert a tensile residual stress of 228.1MPa was observed in the workpiece. The results also revealed the variation of flank wear on the tool with different cutting inserts. The conclusions was drawn on the hard turning of hard chrome plated by adopting proper cutting conditions to replace the grinding operation by hard turning operation.

The Effects of Ultrasonic Nanocrystal Surface Modification Technique Temperature on Microstructure and Wear of Alloy 600

2016 ◽  
Vol 879 ◽  
pp. 926-931
Author(s):  
Jun Hyong Kim ◽  
Auezhan Amanov ◽  
Young Sik Pyun
Keyword(s):  
Residual Stress ◽  
Corrosion Resistance ◽  
Surface Modification ◽  
High Temperature ◽  
Compressive Residual Stress ◽  
Wear Behavior ◽  
Treatment Temperature ◽  
Alloy 600 ◽  
Term Operation ◽  
Superior Corrosion Resistance

Alloy 600 (UNS N06600) is an austenitic nickel-based alloy with superior corrosion resistance and high-temperature endurance, which determines its widespread applications in aeronautical, aerospace, marine and nuclear industries. Particularly, a number of nuclear components used Alloy 600 as their structure materials due to their high corrosion resistance, high-temperature endurance and excellent fabricant characteristics. Many failures have occurred in Alloy 600 with various forms of environmental degradations during long-term operation. In this study, an ultrasonic nanocrystal surface modification (UNSM) technique was applied to Alloy 600 at a room and a high temperature of 500 OC. The effects of UNSM treatment temperature on the microstructure and wear behavior including a compressive residual stress were investigated. The hardness, compressive residual stress with respect to depth from the top surface were measured. Also, the wear behavior of UNSM-treated at a room and a high temperature Alloy 600 specimen was compared to that of the untreated specimen. The increase in wear resistance by UNSM technique was discussed in terms of increased hardness, refined grain size and induced compressive residual stress.

scholarly journals Enhancement of Fatigue Endurance Limit through Ultrasonic Surface Rolling Processing in EA4T Axle Steel

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 830
Author(s):  
Xiaodi Wang ◽  
Liqin Chen ◽  
Peng Liu ◽  
Guobiao Lin ◽  
Xuechong Ren
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Fatigue Limit ◽  
Compressive Residual Stress ◽  
Endurance Limit ◽  
Static Load ◽  
Fatigue Testing ◽  
Fatigue Property ◽  
Surface Characteristics ◽  
Fatigue Endurance

Fatigue property is a key evaluation index for the service reliability of railway axle. In this work, the effect of ultrasonic surface rolling processing (USRP) on the surface characteristic and fatigue property was investigated in an EA4T axle steel used on high speed trains by several characterization techniques and the staircase method fatigue testing. The surface characteristics were initially studied in EA4T axle steel under different static loads of 1.0 kN, 1.5 kN and 2.0 kN, and served as the important USRP parameter. It was found that the larger static load greatly improved the surface microstructure, microhardness and compressive residual stress, but also increased the surface roughness. Furthermore, the rotating bending fatigue endurance limit of the USRP specimen with a static load of 1.5 kN was obviously enhanced by ~14% (from ~352 MPa to ~401 MPa) relative to the untreated specimen. The enhanced fatigue limit induced by USRP was attributed to the synergistic effect of the grain refinement, as evidenced by transmission electron microscope (TEM) observation, work-hardening, the increased compressive residual stress and the reduced surface roughness. Moreover, the fatigue limit of the USRP specimen was ~4% higher than that of the rolling specimen with turning off the ultrasonic system, ~386 MPa, which showed that the role of the ultrasonic impact could enhance the fatigue property. These findings demonstrate the validity of this technique in modifying the surface characteristics and thus improving the fatigue resistance of axle material, further ensuring its service safety and reliability.

FATIGUE CHARACTERISTICS OF SKD-61 BY ULTRASONIC NANOCRYSTAL SURFACE MODIFICATION TECHNOLOGY UNDER STATIC LOAD VARIATION

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2645-2650 ◽  
Author(s):  
CHANG-MIN SUH ◽  
MOON-HWAN LEE ◽  
YOUNG-SIK PYOUN
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Surface Modification ◽  
Compressive Residual Stress ◽  
Static Load ◽  
Crystal Surface ◽  
Load Level ◽  
Surface Plastic ◽  
Smooth Specimen ◽  
Load Variation

At first, the specimens of SKD-61 are prepared and tested to verify the effects of ultrasonic nano-crystal surface modification (UNSM) technology on the variation of mechanical properties under static load variation. 20 kHz frequency was applied to the ball tip, and the applied static forces were changed three kinds of load level 40, 60, and 80 N, respectively. The grain size of SKD-61 surface treated by UNSM becomes very fine to nano-scale crystal and structure is observed till certain depth. The compressive residual stress becomes -810, -1200 and -1400 MPa to a 150 µm depth after the UNSM process according to three kinds of load level 40, 60, and 80 N, respectively. Fatigue limits of 107 cycles are increased by 8.3, 11.2, and 17.9% after UNSM at the smooth specimen according to three kinds of load level, respectively. Interior-originating fracture, fish-eye crack, occurs after UNSM because of a nano structured modification by a surface plastic deformation and compressive residual stress in the case of the smooth specimen. UNSM improves the mechanical properties effectively and is becoming a practical method to improve the service life of the trimming knives. Productivity and reliability of a cold rolling process have improved more than 2 times by the application of the UNSM trimming knives.

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