Evaluating the fatigue limit of metals having surface compressive residual stress and exhibiting shakedown

2019 ◽  
Vol 43 (2) ◽  
pp. 211-220 ◽  
Author(s):  
Jinta Arakawa ◽  
Tatsuya Hanaki ◽  
Yoshiichirou Hayashi ◽  
Hiroyuki Akebono ◽  
Atsushi Sugeta
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Compressive Residual Stress

Effect of Pre-Strain and Roller Working on Torsional Fatigue Properties of a Structural Steel

2011 ◽  
Vol 295-297 ◽  
pp. 2227-2230
Author(s):  
Cong Ling Zhou
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Work Hardening ◽  
Compressive Residual Stress ◽  
Strain Ratio ◽  
Fatigue Tests ◽  
The Other ◽  
Fatigue Properties ◽  
Torsional Fatigue ◽  
Stress Work

In this study, fatigue tests have been performed using two kinds of specimens made of 25 steel. One is pre-strained specimen with pre-strain ratio changing from 2% to 8% by tension, the other is roller worked with deformation of 0.5 mm and 1.0 mm in diameter direction. In the case of pre-strained specimen, the fatigue limit increases according to increase of tensile pre-strain, the fatigue limit of 8% pre-strained specimen is 25% higher than that of non-pre-strained one; in the case of roller worked specimen, the fatigue limit of R05 and R10 is 126% and 143% to that of non-roller worked specimen, respectively. These remarkable improvements of fatigue limit would be caused by the existence of compressive residual stress, work-hardening and the elongated microscopic structures.

Effect of Shot Peening on Fatigue Properties of Zr-based Amorphous Matrix Composites

2011 ◽  
Vol 1300 ◽  
Author(s):  
Changwoo Jeon ◽  
Choongnyun Paul Kim ◽  
Sunghak Lee
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Amorphous Matrix ◽  
Fatigue Cracks ◽  
Microstructural Analysis ◽  
Fatigue Properties ◽  
Composite Surface ◽  
Cast Composite

AbstractEffects of shot peening on fatigue properties of Zr-based amorphous matrix composite containing ductile crystalline particles were investigated, and fatigue processes were analyzed and compared with those of an as-cast composite. The microstructural analysis results of the shot-peened composite surface indicated that the deformation and surface flexion were observed as the shot-peening time or pressure increased. The compressive residual stress formed on the shot-peened surface was about the half of the ultimate tensile strength, and was not varied much with shot-peening time or pressure. The fatigue limit and fatigue ratio of the shot-peened composite were considerably higher than those of the as-cast composite. This was because the compressive residual stress formed by the shot peening induced the initiation of fatigue cracks at the specimen interior, instead of the specimen surface, thereby leading to the enhanced fatigue limit and fatigue life.

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.

scholarly journals Fatigue Limit of Custom 465 with Surface Strengthening Treatment

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 238 ◽  
Author(s):  
Gang An ◽  
Ren-jing Liu ◽  
Guang-qiang Yin
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Limit ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Subsurface Layer ◽  
Micro Hardness ◽  
Surface Residual Stress ◽  
Surface Strengthening ◽  
The Relationship

In order to study the effect of nitriding or shot peening on the surface modification and fatigue properties of martensitic stainless-steel Custom 465, the residual stress and micro-hardness of the strengthened layer are determined by X-ray and micro-hardness tester, respectively. The up-and-down method is used to measure the rotational bending fatigue strength at 1 × 107 cycles, and the fatigue fracture characteristic is observed by scanning electron microscopy. The relationship between surface residual stress and internal fatigue limit of surface strengthening treatment is discussed. Results show that nitriding or shot peening surface strengthening layer forms a certain depth of compressive residual stress, where in the surface compressive residual stress of the nitrided specimens is greater than the shot peened specimens. The micro-hardness of the nitrided or shot peened surface strengthening layer is significantly improved, where in the surface micro-hardness of nitriding specimens are higher than shot peening specimens. The nitriding or shot peening surface strengthening can significantly improve the fatigue limit of Custom 465, wherein the fatigue limits of nitrided and shot peened surface strengthened specimens are 50.09% and 50.66% higher than that of the un-surface strengthened specimens, respectively. That is, the effect of the two strengthening methods on fatigue limit is not very different. The fracture characteristics show that the fatigue crack of the un-surface strengthened specimens originates from the surface, while the fatigue crack of surface strengthened specimens originates from the subsurface layer under the strengthened layer. The relationship between the internal fatigue limit and the surface residual stress of the surface strengthened specimen can be used as a method for predicting the fatigue limit of the surface strengthened specimens.

The establishment of the fatigue limit diagram in consideration of compressive residual stress of ASTM CA6NM stainless cast steel

2016 ◽  
Vol 2016 (0) ◽  
pp. OS02-34
Author(s):  
Tatsuya HANAKI ◽  
Yoshiichiro HAYASHI ◽  
Hiroyuki AKEBONO ◽  
Masahiko KATO ◽  
Atsushi SUGETA
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Compressive Residual Stress ◽  
Cast Steel

scholarly journals Improving Fatigue Limit and Rendering Defects Harmless through Laser Peening in Additive-Manufactured Maraging Steel

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 49
Author(s):  
Shiori Tsuchiya ◽  
Koji Takahashi
Keyword(s):  
Residual Stress ◽  
Fatigue Strength ◽  
Fatigue Limit ◽  
Maraging Steel ◽  
Compressive Residual Stress ◽  
Surface Defects ◽  
Defect Size ◽  
Specimen Surface ◽  
Dominant Factor ◽  
Laser Peening

Additive-manufactured metals have a low fatigue limit due to the defects formed during the manufacturing process. Surface defects, in particular, considerably degrade the fatigue limit. In order to expand the application range of additive-manufactured metals, it is necessary to improve the fatigue limit and render the surface defects harmless. This study aims to investigate the effect of laser peening (LP) on the fatigue strength of additive-manufactured maraging steel with crack-like surface defects. Semicircular surface slits with depths of 0.2 and 0.6 mm are introduced on the specimen surface, and plane bending-fatigue tests are performed. On LP application, compressive residual stress is introduced from the specimen surface to a depth of 0.7 mm and the fatigue limit increases by 114%. In a specimen with a 0.2 mm deep slit, LP results in a high-fatigue-limit equivalent to that of a smooth specimen. Therefore, a semicircular slit with a depth of 0.2 mm can be rendered harmless by LP in terms of the fatigue limit. The defect size of a 0.2 mm deep semicircular slit is greater than that of the largest defect induced by additive manufacturing (AM). Thus, the LP process can contribute to improving the reliability of additive-manufactured metals. Compressive residual stress is the dominant factor in improving fatigue strength and rendering surface defects harmless. Moreover, the trend of the defect size that can be rendered harmless, estimated based on fracture mechanics, is consistent with the experimental results.

scholarly journals Effect of surface compressive residual stress introduced by surface treatment on fatigue properties of metallic material

2018 ◽  
Vol 165 ◽  
pp. 18006
Author(s):  
Jinta Arakawa ◽  
Tatsuya Hanaki ◽  
Yoshiichirou Hayashi ◽  
Hiroyuki Akebono ◽  
Atsushi Sugeta
Keyword(s):  
Residual Stress ◽  
Surface Treatment ◽  
Fatigue Limit ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Mean Stress ◽  
Metallic Material ◽  
Effect Of Surface

This study considers shakedown in evaluating the fatigue limit of metals with compressive residual stress at the surface. We begin by applying tension-compression fatigue tests to ASTM CA6NM under conditions of controlled load and displacement to obtain fatigue limit diagram in compressive mean stress. The results imply that shakedown occurs under the condition of controlled displacement, therefore, shakedown should be considered when evaluating the fatigue limit of metals with compressive residual stress at the surface.

Monitoring of mechanical properties of prestressed glass fiber epoxy composites over 12 months after fabrication

2021 ◽  
pp. 002199832110047
Author(s):  
Mahmoud Mohamed ◽  
Siddhartha Brahma ◽  
Haibin Ning ◽  
Selvum Pillay
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Flexural Strength ◽  
Compressive Residual Stress ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Initial Increase ◽  
Fiber Volume

Fiber prestressing during matrix curing can significantly improve the mechanical properties of fiber-reinforced polymer composites. One primary reason behind this improvement is the generated compressive residual stress within the cured matrix, which impedes cracks initiation and propagation. However, the prestressing force might diminish progressively with time due to the creep of the compressed matrix and the relaxation of the tensioned fiber. As a result, the initial compressive residual stress and the acquired improvement in mechanical properties are prone to decline over time. Therefore, it is necessary to evaluate the mechanical properties of the prestressed composites as time proceeds. This study monitors the change in the tensile and flexural properties of unidirectional prestressed glass fiber reinforced epoxy composites over a period of 12 months after manufacturing. The composites were prepared using three different fiber volume fractions 25%, 30%, and 40%. The results of mechanical testing showed that the prestressed composites acquired an initial increase up to 29% in the tensile properties and up to 32% in the flexural properties compared to the non-prestressed counterparts. Throughout the 12 months of study, the initial increase in both tensile and flexural strength showed a progressive reduction. The loss ratio of the initial increase was observed to be inversely proportional to the fiber volume fraction. For the prestressed composites fabricated with 25%, 30%, and 40% fiber volume fraction, the initial increase in tensile and flexural strength dropped by 29%, 25%, and 17%, respectively and by 34%, 26%, and 21%, respectively at the end of the study. Approximately 50% of the total loss took place over the first month after the manufacture, while after the sixth month, the reduction in mechanical properties became insignificant. Tensile modulus started to show a very slight reduction after the fourth/sixth month, while the flexural modulus reduction was observed from the beginning. Although the prestressed composites displayed time-dependent losses, their long-term mechanical properties still outperformed the non-prestressed counterparts.

scholarly journals Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2767
Author(s):  
Ki-Won Jeong ◽  
Jung-Suk Han ◽  
Gi-Uk Yang ◽  
Dae-Joon Kim
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Low Temperature ◽  
Compressive Residual Stress ◽  
Yttria Stabilized Zirconia ◽  
Ambient Atmosphere ◽  
Aged Specimen ◽  
Stabilized Zirconia ◽  
M Phase ◽  
The Relationship

Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.

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