scholarly journals Influence of Crystal Structure of Nitride Compound Layer on Torsion Fatigue Strength of Alloy Steel

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1352 ◽  
Author(s):  
Yoshitomi Yamada ◽  
Eto Hirohito ◽  
Koji Takahashi
Keyword(s):  
Crystal Structure ◽  
Fatigue Strength ◽  
Crystal Structures ◽  
Alloy Steel ◽  
High Strength ◽  
Compound Layer ◽  
Fatigue Tests ◽  
Commercial Vehicles ◽  
Torsional Fatigue ◽  
Number Of Cycles

The demand for high-strength components for commercial vehicles has recently increased. Conventional gas nitrocarburizing has been used to increase strength and productivity of the crankshaft. A potential-controlled nitriding process was recently developed to control the crystal structure of the nitride compound layer. It has been found that this treatment improves the bending fatigue strength compared with conventional treatment, and has the potential to cope with the increase in crankshaft strength. However, the effect of torsional fatigue strength has not been studied. Therefore, in this study, the influence of the crystal structure of the nitride compound layer on torsional fatigue strength was investigated. Two kinds of test specimens with different crystal structures of the compound layer were prepared using gas nitriding treatment with controlled nitriding potential for an alloy steel bar (JIS-SCM435). Torsional fatigue tests were carried out using these test specimens. Although the compound layer of these test specimens had different crystal structures, the hardness distribution and residual stress distribution on the diffusion layer were almost the same. The relationship between stress amplitude and number of cycles to failure (S-N curve) showed that the torsional fatigue limits of the specimens were almost the same. This indicates that the crystal structure of the nitride compound layer did not affect the torsional fatigue limits, because the origin of the torsional fatigue failure is inside the specimen.

scholarly journals Determination of the Mechanical Properties of Friction Welded Tube Yoke and Tube Joint

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Efe Işık ◽  
Çiçek Özes
Keyword(s):  
Tensile Strength ◽  
Friction Welding ◽  
Welded Joint ◽  
Fatigue Tests ◽  
Commercial Vehicles ◽  
Base Materials ◽  
Torsional Fatigue ◽  
Welding Interface ◽  
Load Carrying ◽  
Welded Tube

This paper deals with the friction welding of the tube yoke and the tube of the drive shaft used in light commercial vehicles. Tube yoke made from hot forged microalloyed steel and the tube made from cold drawn steel, with a ratio (thickness/outside diameter ratio) of less than 0.1, were successfully welded by friction welding method. Hardness distributions on both sides of the welded joint across the welding interface were determined and the microstructure of the joint was investigated. Furthermore, joint strength was tested under tensile, static torsional, and torsional fatigue loadings. The tested data were analyzed by Weibull distribution. The maximum hardness value along the welded joint was detected as 553 Hv1. The lowest detected tensile strength of the joint was 13% less than the base materials’ tensile strength. The torsional load carrying capacity of the friction welded thin walled tubular joint without any damage was obtained as 4.252,5 Nm in 95% confidence interval. After conducting fully reversed torsional fatigue tests, the fatigue life of friction welded tubular joints was detected as 220.066,3 cycles.

Influence of Strength Level of Steels on Fatigue Strength and Fracture Morphology of Spot Welded Joints

2011 ◽  
Vol 462-463 ◽  
pp. 94-99
Author(s):  
Keiichiro Tohgo ◽  
Tomoya Ohguma ◽  
Yoshinobu Shimamura ◽  
Yoshifumi Ojima
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Mild Steel ◽  
Welded Joints ◽  
High Strength ◽  
Fracture Morphology ◽  
Fatigue Tests ◽  
Finite Element Analyses ◽  
Ultra High Strength Steel ◽  
Spot Welded

In this paper, fatigue tests and finite element analyses are carried out on spot welded joints of mild steel (270MPa class) and ultra-high strength steel (980MPa class) in order to investigate the influence of strength level of base steels on fatigue strength and fracture morphology of spot welded joints. From the fatigue tests the following results are obtained: (1) Fatigue limit of spot welded joints is almost the same in both steels. (2) Fatigue fracture morphology of spot welded joints depends on the load level in the ultra-high strength steel, but not in the mild steel. From discussion based on the finite element analyses the following results are obtained: (3) The fatigue limit of spot welded joints can be predicted by stress intensity factors for a nugget edge, fracture criterion for a mixed mode crack and threshold value for fatigue crack growth in base steel. (4) Plastic deformation around a nugget in spot welded joints strongly affects the fatigue fracture morphology.

Torsional Fatigue of 63Sn-37Pb and Sn-0.7Cu Solders

2007 ◽  
Vol 353-358 ◽  
pp. 2908-2911
Author(s):  
Ning Bai ◽  
Xu Chen ◽  
Xin Li
Keyword(s):  
Steady State ◽  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Equivalent Strain ◽  
Fatigue Tests ◽  
Load Drop ◽  
Torsional Fatigue ◽  
Von Mises ◽  
Fatigue Criterion ◽  
Better Than

A series of torsional fatigue tests were conducted on 63Sn-37Pb and Sn-0.7Cu solders. A continuous load drop was observed during the test. It was found that the load drop percentage had little effect on the elastic strain-life curve but strong effect on the plastic strain-life curve. The fatigue strength coefficient, fatigue strength exponent and fatigue ductility exponent had no great changes with the load drop. However, fatigue ductility coefficient showed a great difference and was linearly varying with load drop. A fatigue criterion of Coffin-Manson type was proposed in relation to load drop. The descending curve of the stress range with cycle was observed to consist of transient, steady state and tertiary regions. The percentage of load drop corresponding to the turning point from the steady state to the tertiary region was about 25% for all strain ranges of 63Sn-37Pb, and 30% for all strain ranges of Sn-0.7Cu. The torsional fatigue lives were correlated with von Mises equivalent strain amplitudes well. The fatigue behavior of Sn-0.7Cu is better than that of 63Sn-37Pb.

scholarly journals USING THE LINEAR DAMAGE SUMMATION HYPOTHESIS IN THE FATIGUE TESTS ANALYSIS OF TITANIUM ALLOY PIECES

2021 ◽  
pp. 1-6
Author(s):  
Evgeniya Gnatyuk ◽  
Arkadiy Skvortsov ◽  
Svetlana Kuleshova
Keyword(s):  
Titanium Alloy ◽  
Endurance Limit ◽  
Linear Regression Analysis ◽  
High Strength ◽  
Fatigue Tests ◽  
Test Pieces ◽  
Operational Testing ◽  
Strength Material ◽  
Number Of Cycles ◽  
Damage Summation

This paper presents the results of fatigue tests of titanium alloy, and also describes the use of the hypothesis of linear damage summation when processing the results of fatigue tests. On the basis of the experiments, the endurance limit of the titanium alloy was determined, which lies in the range from 460 to 480 MPa with the number of cycles from 105 to 108. The purpose of the experiment was to determine the endurance limit of high strength material, as well as a mathematical measurement of the expected destruction. In this study, empirical methods were used such as indirect observation of the object under study, description and measurement of technical influences exerted on it by an artificial means, as well as linear regression analysis to establish the relationship between stress and durability. As a result of the experiment, fatigue curves were obtained for various probabilities, which give grounds to conclude that the use of the linear damage summation hypothesis in processing the results of fatigue tests entails a satisfactory practical accuracy of the calculation of endurance limit. This experiment is aimed at improving metal production by studying the quality of titanium alloy test pieces and performing mathematical analysis of possible problems arising in the process of its operational testing.

Proposal for the Implementation of Elevated Temperature Design Fatigue Curve for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V Steels

2004 ◽  
Author(s):  
Tatsumi Takehana ◽  
Takeru Sano ◽  
Susumu Terada ◽  
Hideo Kobayashi
Keyword(s):  
Elevated Temperature ◽  
Fatigue Strength ◽  
High Strength ◽  
Fatigue Curve ◽  
Temperature Limit ◽  
Fatigue Tests ◽  
Low Alloy Steels ◽  
Alloy Steels ◽  
Elevated Temperature Design

2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels have been used extensively as materials for elevated temperature and high-pressure hydro-processing reactors. These steels have both of high strength at elevated temperature and high resistance against elevated temperature hydrogen attack due to the addition of vanadium. The operating temperature of these reactors is between 800 and 900deg.F. The fatigue evaluations of these reactors per ASME Sec. VIII Div.2 and Div.3 can’t be performed in spite of demand for fatigue analysis because the temperature limit of design fatigue curve in ASME Sec. VIII Div.2 and Div.3 for carbon and low alloy steels is 700deg.F. Results of load and strain controlled fatigue tests conducted over the temperature range from room temperature to 932deg.F (500deg.C) are reported for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels. These data were compared with data for 2-1/4Cr-1Mo steels available from the literatures. The fatigue strength for a 2-1/4Cr-1Mo-V steel in high cycle region is higher than that for 2-1/4Cr-1Mo steels and in low cycle region is lower. The fatigue strength for a 3Cr-1Mo-V steel is almost same as that for 2-1/4Cr-1Mo-V steels. Therefore an elevated temperature design fatigue curve for 2-1/4Cr-1Mo-V and 3Cr-1Mo-V steels is newly proposed. It is found from the case study that the different fatigue life can be predicted by using different mean stress correction procedure.

scholarly journals Weld toe modification using spherical-tip WC tool FSP in fatigue strength improvement of high-strength low-alloy steel joints

2018 ◽  
Vol 160 ◽  
pp. 1019-1028 ◽  
Author(s):  
Hajime Yamamoto ◽  
Yoshikazu Danno ◽  
Kazuhiro Ito ◽  
Yoshiki Mikami ◽  
Hidetoshi Fujii
Keyword(s):  
Fatigue Strength ◽  
Alloy Steel ◽  
High Strength ◽  
Low Alloy Steel ◽  
Fatigue Strength Improvement ◽  
Weld Toe ◽  
Steel Joints ◽  
Strength Improvement

Fatigue Strength Assessment for High Strength Steel Welded Joints

2010 ◽  
Author(s):  
Ho Jung Kim ◽  
Sung Won Kang ◽  
Jae Myung Lee ◽  
Myung Hyun Kim
Keyword(s):  
Fatigue Strength ◽  
Welded Joints ◽  
High Strength Steel ◽  
Fatigue Behavior ◽  
High Strength ◽  
Fatigue Tests ◽  
Cold Metal Transfer ◽  
Strength Assessment ◽  
Back Plate ◽  
Cold Metal

The aim of the present paper is to investigate and to compare the fatigue characteristics of butt welded joints made of high strength steel with tensile strength 700MPa. The influence of different back plate materials and the groove shapes of copper backing are investigated. Various backing methods have been used in the steel construction industries, but steel backing, which is the most frequently used, sometimes is not capable of providing sufficient fatigue strengths for welded joint, particularly for high strength steel. Therefore, alternative backing methods have been investigated in order to improve the fatigue strength by employing ceramic backing, CMT (Cold Metal Transfer) [1] and copper backing. The main objective of the work is to estimate the fatigue test results for improving fatigue strength by comparing different backing materials and groove shapes. A series of fatigue tests with different types of backings has been carried out to obtain the fatigue life of butt welded joints. It was observed that the fatigue behavior of welded joints can be substantially improved by changing back bead shapes. The result has shown that the back bead shape of copper backing is better than others except for that of CMT, accompanied by improved fatigue strength.

Retrofitting for Fatigue Cracks at Connection between the Main Girder Web and Lateral Girder Flange Using the Bolting-Stop-Hole Method with Attached Plates

2014 ◽  
Vol 891-892 ◽  
pp. 130-135
Author(s):  
Takeshi Mori ◽  
Kazuya Sasaki ◽  
Mitsuru Nakanuma
Keyword(s):  
Fatigue Crack ◽  
Fatigue Strength ◽  
Fatigue Cracks ◽  
High Strength ◽  
Fatigue Tests ◽  
Steel Plates ◽  
Small Scale ◽  
Bolted Connections ◽  
Repair Method ◽  
Main Girder

For the purpose of clarifying the fatigue strength of a main girder web connected to a lateral girder flange which is repaired by bolting-stop-hole method with attached steel plates, fatigue tests have been performed on girder specimens. In addition, fatigue tests have been also carried out on small scale plate specimens modeling the repaired parts in order to investigate the fatigue crack origin and fatigue strength of the repaired parts. Furthermore, the effect of the repair method has been compared with those of stop-hole method and/or bolting-stop-hole method through the fatigue tests. It has been confirmed that the fatigue strength of the repaired parts is considerably high and almost equal to that of friction type of high strength bolted connections.

Effect of Radical Nitriding on Fatigue Strength of Ni-Base Superalloy

2009 ◽  
Vol 417-418 ◽  
pp. 205-208 ◽  
Author(s):  
Kazuhiro Morino ◽  
Norio Kawagoishi ◽  
K. Yamane ◽  
K. Fukada
Keyword(s):  
Fatigue Strength ◽  
Base Alloy ◽  
Compound Layer ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Propagation Behavior ◽  
Initiation And Propagation ◽  
Rotating Bending Fatigue ◽  
Rotating Bending ◽  
Base Superalloy

In order to investigate the effect of nitriding on the crack initiation and propagation behavior of Ni-base super alloy, Alloy 718, rotating bending fatigue tests were carried out until 108 cycles at room temperature. By nitriding at 500°C for 12h, compound layer of about 5μm in thickness was formed and the initiation of a fatigue crack was strongly suppressed causing the increase in fatigue strength. A crack initiated in brittle manner at the compound layer in all of fractures. However the crack propagated in ductile manner controlled by the property of the base alloy. That is, there is no or little influence of nitriding on the crack growth rate of the alloy.

Fatigue Strength of Small Pinned Connections Made from Alloy Steel Fv 520B

1967 ◽  
Vol 182 (1) ◽  
pp. 615-630 ◽  
Author(s):  
D. J. White
Keyword(s):  
Fatigue Strength ◽  
Alloy Steel ◽  
Design Method ◽  
Systematic Investigation ◽  
Fatigue Tests ◽  
Mean Stress ◽  
Interference Fit ◽  
Cadmium Plating ◽  
Engineering Sciences ◽  
Pinned Connections

Published work on pin-loaded lugs is reviewed, particular attention being given to photoelastically determined stress distributions and to results of fatigue tests for the purpose of identifying those factors that affect fatigue strength. Fatigue tests have been conducted on lugs of width 1 [Formula: see text] in made from alloy steel FV 520B and loaded by means of a [Formula: see text]-in diameter pin. A systematic investigation was made of pin fit for both clearance and interference and the effect of various treatments was investigated; these included cadmium plating the lug bore and pin, applying the ‘Sulfinuz’ process to the lug and overstraining the lug bore. Two conditions of mean stress were investigated, namely, pulsating or repeated tension and 15 tonf/in2 mean tension. Strength comparisons are based on the fatigue strength at 108 cycles, for the appropriate mean stress, of untreated lugs with exact-fit pins, these showing the lowest strength of all the lugs tested. It was found that clearance-fit pins and interference-fit pins were beneficial and with the larger values of clearance and interference tested the fatigue strength was almost doubled. Cadmium plating was ineffective while both Sulfinuz treated lugs and lugs with overstrained bores gave strength ratios of at least 1.6. An increase in mean stress from pulsating tension to 15 tonf/in2 mean tension, significantly reduced fatigue strength in most cases. On the basis of the present experimental results, the design method proposed for lugs with interference-fit pins in Royal Aeronautical Society Data Sheet A.05.02, amended by Engineering Sciences Data No. 67012, may sometimes prove to be unsafe and caution is warranted in interpreting the safe loads predicted.

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