scholarly journals The effects of robot welding and manual welding on the low- and high-cycle fatigue lives of SM50A carbon steel weld zones

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401982826
Author(s):  
Changwan Han ◽  
Changhwan Yang ◽  
Hanjong Kim ◽  
Seonghun Park
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Arc Welding ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Weld Zone ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Three Point Bending ◽  
Robot Welding

The purpose of this study is to analyze the differences between the effects of robot welding and manual welding on the low- and high-cycle fatigue lives of the weld zones for T-shaped weld structures fabricated from SM50A carbon steel using a CO2 gas arc welding method. Fatigue tests were conducted using a three-point bending method, and the S-N curves of the manual welding and robot welding crossed each other at approximately 3 × 104 cycles. The robot welding weld zone had better high-cycle fatigue lives than the manual welding. The results are attributable to the fact that the more uniform and higher welding speed of the robot welding leads to smaller weld zone area (i.e. ~12% smaller than the manual welding) and also smaller grain size than the manual welding. Because a smaller grain size in the robot welding weld zone results in a higher hardness than the manual welding and material brittleness increases with increasing hardness, the robot welding weld zone shows better high-cycle fatigue lives but poorer low-cycle fatigue lives than the manual welding.

Effect of Different Welded Structures on Mechanical Properties of TA2 Tube-to-Tubesheet Joints

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Xinlong Wei ◽  
Yang Qian ◽  
Junhui Wang ◽  
Jianxin Zhou ◽  
Xiang Ling
Keyword(s):  
Applied Load ◽  
Low Cycle Fatigue ◽  
Weld Zone ◽  
Steel Tube ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Welded Structures ◽  
Pull Out ◽  
Weld Toe ◽  
Welded Tube

Four types of TA2 welded tube-to-tubesheet joints prepared by manual tungsten arc argon-shielded welding technique are studied in this paper. The pull-out tests and low cycle fatigue tests were performed to optimize welded structures of tube and tubesheet. The results show that fractures of welded TA2 tube and tubesheet samples occur at weld zone of TA2 steel tube for the pull-out tests and low cycle fatigue tests. The extension-tubesheet welded joints have the maximum pull-out forces and the best fatigue resistance, and the internal-bore welded joint with 45 deg bevel occupies second place. Fractures are both initiated from weld toe of the outside of tube for the pull-out tests and low cycle fatigue tests. Crack propagates along the direction of 45 deg for the pull-out test. However, crack propagates perpendicularly to the direction of the applied load for low cycle fatigue test, and then fractures immediately parallel to the direction of the applied load. Fatigue striations with a spacing of about 10 μm can be observed on the fatigue crack propagation zone. However, hemispheroidal dimples exist on instant rupture zone.

scholarly journals Effect of Grain Size on Low Cycle Fatigue in Low Carbon Steel

1981 ◽  
Vol 24 (196) ◽  
pp. 1692-1699 ◽  
Author(s):  
Kenji HATANAKA ◽  
Toshiro YAMADA
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Low Cycle Fatigue ◽  
Low Carbon Steel ◽  
Cycle Fatigue ◽  
Low Carbon

Modification of the Equation for Description of Wöhler's Curves

2010 ◽  
Vol 27 (1) ◽  
pp. 99-104 ◽  
Author(s):  
Sylwester Kłysz ◽  
Janusz Lisiecki ◽  
Tomasz Bąkowski
Keyword(s):  
Experimental Data ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Fatigue Threshold ◽  
Cycle Fatigue ◽  
Exponential Equation ◽  
The Way

Modification of the Equation for Description of Wöhler's Curves The paper presents the way to modify the equation σ = f(2Nf) in order to improve the fit of experimental results from High Cycle Fatigue tests. In particular, the study deals with introduction of the 5-parameter exponential equation that enables better fit of the full Wöhler's curve to experimental data within the range of stress at the level of fatigue threshold as well as approximation to the quasi-static range and Low Cycle Fatigue tests for the highest stress values. It is illustrated how individual parameters affect the procedure and possibility to match the aforementioned equation to experimental data.

scholarly journals Experimental Study on Forged TC4 Titanium Alloy Fatigue Properties under Three-Point Bending and Life Prediction

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5329
Author(s):  
Bohan Wang ◽  
Li Cheng ◽  
Dongchun Li
Keyword(s):  
Titanium Alloy ◽  
Life Prediction ◽  
High Cycle Fatigue ◽  
Fatigue Cracks ◽  
Fracture Morphology ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Three Point Bending ◽  
Tc4 Titanium Alloy

Ultrasonic fatigue tests of TC4 titanium alloy equiaxed I, II and bimodal I, II obtained by different forging processes were carried out in the range from 105 to 109 cycles using 20 kHz three-point bending. The results showed that the S-N curves had different shapes, there was no traditional fatigue limit, and the bimodal I had the best comprehensive fatigue performance. The fracture morphology was analyzed by SEM, and it was found that the fatigue cracks originated from the surface or subsurface facets, showing a transgranular quasi-cleavage fracture mechanism. EDS analysis showed that the facets were formed by the cleavage of primary α grains, and the fatigue cracks originated from the primary α grain preferred textures, rather than the primary α grain clusters. From the microstructure perspective, the reasons for better equiaxed high-cycle-fatigue properties and better bimodal ultra-high-cycle-fatigue properties were analyzed. The bimodal I fatigue life prediction based on energy was also completed, and the prediction curve was basically consistent with the experimental data.

scholarly journals Comments on Linear Summation Hypothesis of Fatigue Failures

2014 ◽  
Vol 21 (3) ◽  
pp. 77-85 ◽  
Author(s):  
Grzegorz Szala
Keyword(s):  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Load Level ◽  
Test Results ◽  
Cycle Fatigue ◽  
Load Spectrum ◽  
Linear Summation ◽  
Analysis Of Results ◽  
Fatigue Failures

Abstract This paper presents a comparative analysis of results of fatigue life calculations with the u se of the linear summation hypothesis of fatigue failures (LHSUZ), confronted with experimental test results. Te calculations and fatigue tests were performed for variable amplitude(VA), two-step and ten-step loading conditions, both in the low-cycle fatigue (LCF) and high-cycle fatigue (HCF) range, for the case of C45 steel as an example. Experimental verification of the hypothesis LHSUZ did not revealed any significant influence of load level and form of load spectrum on conformity of results of the calculation by using the LHSUZ, to results of fatigue tests on C45 steel. However, it enabled to assess magnitude of a correction factor which appears in the considered linear hypothesis.

scholarly journals Experimental Stress Analysis for Four 24-in. ANSI Standard B16.9 Tees

1977 ◽  
Vol 99 (4) ◽  
pp. 537-552 ◽  
Author(s):  
J. K. Hayes ◽  
S. E. Moore
Keyword(s):  
Carbon Steel ◽  
Nuclear Power ◽  
Low Cycle Fatigue ◽  
Branch Pipe ◽  
Fatigue Tests ◽  
Elastic Response ◽  
Experimental Stress ◽  
Stress Distributions ◽  
Cycle Fatigue ◽  
Experimental Stress Analysis

This paper describes the experimental stress analysis of low cycle fatigue tests of four tees tested by Combustion Engineering, Inc. (C-E) under subcontract to Union Carbide Nuclear Division. These tests are part of the ORNL Design Criteria for Piping and Nozzles Program which is being conducted for the development of design criteria for nuclear power plant service piping components. The test assemblies were fabricated at C-E from commercially obtained ANSI B16.9 tees and matching diameter steel pipes welded to the tees, with suitable end closures and fixtures for applying the loads. The tees tested and discussed in this report are described in the following: Tee Number/Material/Nominal Size: T–11/carbon steel/24″×24″×24″ sch 160; T–12/carbon steel/24″×24″×10″ sch 40; T–13/carbon steel/24″×24″×10″ sch 160; T–16/stainless steel/24″×24″×24″ sch 10. Each tee test assembly was instrumented with approximately 240 rectangular strain gage rosettes for determining elastic stress distributions, and six linear variable displacement transducers for determining flexibility factors. Elastic-response tests were conducted for 12 loading conditions consisting of internal pressure, pure bending and torsional moments and direct force loads applied individually to the branch pipe extension and to one end of the run pipe. The other run pipe extension was fixed rigidly to the loading frame. Automatic data handling equipment and data reduction techniques were used to process the strain gage readings. For each loading condition, stress distributions were determined and the locations and magnitudes of the maximum stresses were identified. Test results are presented and compared with appropriate design formulas of the ASME Boiler and Pressure Vessel Code, Section III. After the elastic-response tests were completed, three of the tees were low-cycle fatigue tested by pressure cycling using transformer oil. The T-11 and T-13 tees were pressure cycled for 100 psig (790 kPa) to 7000 psig (48 360 kPa); whereas, the T-12 tee was pressure cycled from 0 psig (100 kPa) to 1800 psig (12 510 kPa). A low-cycle fatigue test was performed on the T-16 tee assembly by applying a bending moment to the branch pipe in the plane of the tee with the tee pressurized to a constant internal pressure of 300 psig (2170 kPa). All low-cycle fatigue tests were performed until a through-the-wall fatigue crack occurred as evidenced by a leak. Subparagraph NB-3653.6 of ASME Code, Section III, Division I, Nuclear Power Plant Components was used to calculate the fatigue design life and comparisons were made with the experimentally determined fatigue life.

Effects of Silicon and Chromium on the Fatigue Properties of Al-Zn-Mg-Cu Cast Alloy

2004 ◽  
Vol 449-452 ◽  
pp. 617-620
Author(s):  
In Bae Kim ◽  
Yong Su Park ◽  
Kyung Hyun Kim ◽  
In Gon Kim
Keyword(s):  
Fatigue Test ◽  
High Cycle Fatigue ◽  
Base Alloy ◽  
Cast Alloy ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Maximum Value ◽  
Metallographic Observation

Effects of Si and Cr additions on the fatigue properties of Al-Zn-Mg-Cu cast alloy were investigated by low and high cycle fatigue tests. It was found that in the low cycle fatigue test, fatigue life of base alloy showed the maximum value of 3,075 cycles, whereas in Si and Cr containing alloys, it was 2,993 and 1,413 cycles, respectively. The same trend was obtained in high cycle fatigue test, i.e., the fatigue strength in base alloy showed the highest value of 104MPa and decreased to 100MPa for Cr containing alloy and 81MPa for Si containing alloy. The fatigue ratio was about 0.20 for all three alloys. The tensile strength of base alloy also showed the maximum value of 513MPa, and decreased with the addition of Si and Cr to 400 and 500MPa, respectively. Metallographic observation revealed that the fatigue crack initiated at the surface and propagated along the grain boundary.

scholarly journals Fatigue Characteristics of Selected Light Metal Alloys

2016 ◽  
Vol 61 (1) ◽  
pp. 271-274 ◽  
Author(s):  
M. Cieśla ◽  
G. Junak ◽  
A. Marek
Keyword(s):  
Titanium Alloy ◽  
Fatigue Life ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Light Metal ◽  
Fatigue Tests ◽  
The Other ◽  
Metal Alloys ◽  
Cycle Fatigue

The paper addresses results of fatigue testing of light metal alloys used in the automotive as well as aerospace and aviation industries, among others. The material subject to testing comprised hot-worked rods made of the AZ31 alloy, the Ti-6Al-4V two-phase titanium alloy and the 2017A (T451) aluminium alloy. Both low- and high-cycle fatigue tests were conducted at room temperature on the cycle asymmetry ratio of R=-1. The low-cycle fatigue tests were performed using the MTS-810 machine on two levels of total strain, i.e.Δεc= 1.0% and 1.2%. The high-cycle fatigue tests, on the other hand, were performed using a machine from VEB Werkstoffprufmaschinen-Leipzig under conditions of rotary bending. Based on the results thus obtained, one could develop fatigue life characteristics of the materials examined (expressed as the number of cycles until failure of sample Nf) as well as characteristics of cyclic material strain σa=f(N) under the conditions of low-cycle fatigue testing. The Ti-6Al-4V titanium alloy was found to be characterised by the highest value of fatigue life Nf, both in lowand high-cycle tests. The lowest fatigue life, on the other hand, was established for the aluminium alloys examined. Under the high-cycle fatigue tests, the life of the 2017A aluminium and the AZ31 magnesium alloy studied was determined by the value of stress amplitude σa. With the stress exceeding 150 MPa, it was the aluminium alloy which displayed higher fatigue life, whereas the magnesium alloy proved better on lower stress.

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