scholarly journals Residual Stress Investigations in Austenitic Steel Samples With Different Degree of Low Cycle Fatigue

1999 ◽  
Vol 33 (1-4) ◽  
pp. 279-289 ◽  
Author(s):  
G. D. Bokuchava ◽  
V. V. Luzin ◽  
J. Schreiber ◽  
Yu. V. Taran
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Austenitic Steel ◽  
Cyclic Load ◽  
Low Cycle Fatigue ◽  
Texture Evolution ◽  
Austenitic Stainless Steels ◽  
Martensite Phase ◽  
Cycle Fatigue ◽  
Stress Evolution

Austenitic stainless steels are widely used because of their high corrosion resistance and toughness. The influence of the applied cyclic load on the mechanical properties of the material is of great current interest. In order to investigate residual stress evolution a series of the austenitic steel samples (X6CrNiTi1810) with different degrees of low cycle fatigue was studied. Martensitic phase formation was observed at different degrees of low cycle fatigue. Residual stresses, microstresses in both phases, as well as martensitic precipitation volume fractions, were estimated. Usually after plastic deformation the martensite phase produces a structure of oriented plates or laths. Therefore martensite texture formation during phase transition can be expected. Indeed the registered neutron diffraction spectra from austenitic fatigued samples show texture presence and its variation in dependence of the fatigue degree. The attempt to consider the texture evolution in dependence of fatigue degree and its influence on the residual stresses was made.

Influence of Initial and Welding Residual Stresses on Low Cycle Fatigue and Ratcheting Response Simulations of Elbows

2017 ◽  
Author(s):  
Nazrul Islam ◽  
Tasnim Hassan
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Simulation Models ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Girth Welding ◽  
Stress States ◽  
Welding Processes

Earlier studies [1] showed that the ANSYS software package customized with an advanced rate-independent constitutive model was unable to simulate some of the low-cycle fatigue responses of elbow components. Hence, simulations are performed to investigate the influence of manufacturing and welding residual stresses on elbow low-cycle fatigue responses. The sequentially coupled thermo-mechanical finite element analysis is performed to determine the initial residual stress states in elbows due to the elbow manufacturing processes and welding of elbows to straight pipes. Real-time girth-welding processes are taken into account to simulate the welding induced residual stress field. Incorporating these initial residual stresses in the computations, low-cycle fatigue and strain ratcheting responses are simulated by ANSYS. The simulation responses demonstrate that the influence of manufacturing and welding residual stresses in elbows on its low-cycle fatigue responses is negligible. Hence, the question remains what is missing in the simulation models that some of the elbow low-cycle fatigue responses cannot be simulated.

scholarly journals Influence of stress ratio on residual stress evolution near cold-expanded hole due to low-cycle fatigue by crack compliance data

2020 ◽  
Vol 15 (55) ◽  
pp. 174-186
Author(s):  
Andrey Chernov ◽  
Sviatoslav Eleonsky ◽  
Vladimir Pisarev
Keyword(s):  
Residual Stress ◽  
Stress Ratio ◽  
Low Cycle Fatigue ◽  
Quantitative Description ◽  
Stress Range ◽  
Cycle Fatigue ◽  
Stress Evolution ◽  
Residual Stress Field ◽  
Field Influence

Modified version of the crack compliance method is used for determination of stress intensity factor (SIF) related to narrow notches emanating from cold-expanded holes. These notches are inserted at different stages of low-cycle fatigue under constant external load. It is shown how residual SIF values, generated by residual stress field influence, can be separated from total experimental SIF values. Residual SIF values, obtained at different stage of low-cycle fatigue with the same stress range Δσ  = 350 MPa but different stress  R = –0.4 and  R = –1.0, provide quantitative description of residual stress evolution near cold-expanded hole. It shown that maximal residual stress relaxation of order 20 per cent occurs at 95 lifetime per cent for both loading programs.

scholarly journals Residual stresses in hot bulk formed parts: microscopic stress analysis for austenite-to-martensite phase transformation

2021 ◽  
Author(s):  
Sonja Uebing ◽  
Dominik Brands ◽  
Lisa Scheunemann ◽  
Jörg Schröder
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Martensite Phase ◽  
Stress Evolution ◽  
Different Types ◽  
Stress States ◽  
Formed Part ◽  
Formula Method

AbstractIn this contribution, the two-scale analysis of residual stress states in a hot bulk formed part with subsequent cooling in the framework of the $$\hbox {FE}^2$$ FE 2 -method is presented. The induction of specific residual stress states in order to improve a component’s properties is an area of current research. In general, residual stresses can be induced inside a component in different ways, e.g., quenching, phase transformation in hot forming processes or dislocation movements. It is widely known that different types of residual stresses can be characterized based on the scale the type acts on. In addition to the macroscopic residual stress analysis, in which residual stresses of first type are considered, this contribution specifically analyzes the microscopic residual stress evolution as a consequence of the cooling of the component.

Stability and Relaxation of Welding Residual Stresses

2011 ◽  
Vol 681 ◽  
pp. 55-60 ◽  
Author(s):  
Majid Farajian ◽  
Thomas Nitschke-Pagel ◽  
Klaus Dilger
Keyword(s):  
Residual Stress ◽  
Yield Strength ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Weld Bead ◽  
Small Scale ◽  
Internal Stresses ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Weld Toe

Residual stress relaxation of butt-welded small scale steel specimens under static and cyclic mechanical loading was investigated. The experiments were carried out on different types of steel with yield strengths between 300 and 1200MPa. The x-ray and neutron diffraction techniques were applied for the residual stresses analysis. The maximum values of initial residual stresses were measured at the weld bead centerline and were not as frequently assumed as high as the yield strength of the material. From fatigue point of view the internal stresses at the weld toe are of importance. It was observed that only a fraction of maximum residual stress accommodated in the weld bead centerline, is available at the weld toe. Under static tensile and compressive loading by increasing the load level the residual stress field relaxes continuously. The relaxation sets in with delay under compression since the tensile residual stresses should be first overcome. Under cyclic loading, once the first relaxation takes place further cyclic relaxation is either not considerable or continues moderately depending on loading conditions. In high cycle fatigue the residual stresses are stable until 2x106 cycles. In low cycle fatigue however the variation of the residual stresses continues until failure. This variation is partly related to crack initiation and propagation. The von Misses failure criterion with the local yield strength as material resistance against plastic deformation was able to describe the relaxation of surface welding residual stresses in low cycle fatigue.

Effects of Heat-Treatment Residual Stress on Low Cycle Fatigue Life of a Turbine Disk in PM Superalloy

2015 ◽  
Author(s):  
Rongqiao Wang ◽  
Da Li ◽  
Dianyin Hu ◽  
Yang Hai ◽  
Jun Song
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Fatigue Life ◽  
Residual Stresses ◽  
Low Cycle Fatigue ◽  
Turbine Disk ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Turbine Disks ◽  
Pm Superalloy

Turbine disks in powder metallurgy (PM) superalloy have been widely used in advanced aeroengines. The production of PM superalloy turbine disks involves a series of heat treatment processes, which would inevitably create residual stresses. It has been proved that the low cycle fatigue (LCF) life of the turbine disk is affected by the residual stresses. The computational simulation of heat treatment is considered as an effective way to evaluate the residual stresses in a turbine disk. A finite element software was used to simulate the heat-treatment processes of a FGH95 turbine disk to obtain the residual stress field. To investigate the relaxation of residual stress in FGH95, smooth bar specimens were measured by X-ray diffraction before and after being loaded. Modified by the residual stresses, SWT model is used to predict the low cycle fatigue life of the turbine disk modified by the residual stress field obtained from the simulation of heat treatment. By the comparison between the prediction modified by the residual stress and the prediction without modification, a considerable decrease in low cycle fatigue life is indicated.

Parameter Analysis for Time-Dependent Low-Cycle Fatigue Life

1994 ◽  
Vol 116 (4) ◽  
pp. 479-482 ◽  
Author(s):  
Koji Yamaguchi ◽  
Kazuo Kobayashi ◽  
Kiyoshi Ijima ◽  
Satoshi Nishijima
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Low Cycle Fatigue ◽  
Austenitic Stainless Steels ◽  
Original Data ◽  
Parameter Analysis ◽  
304 Stainless Steel ◽  
Cycle Fatigue ◽  
Well Test ◽  
Design Code

Temperature and strain rate dependences of low-cycle fatigue life can be represented by a modified Larson-Miller parameter. The parameter P is written by P=T(logN25−Alog ε˙ + B), where T is temperature, N25 is fatigue life, ε˙ is strain rate, and A and B are constants. In the analysis, each data of several kinds of engineering materials from ferritic steels to austenitic stainless steels are used. These are the authors original data published in the documents of NRIM Fatigue Data Sheets. The result of 304 stainless steel has been compared with statistical analysis result by Diercks adopted in a design code. The fatigue life curves represented by the proposed parameter analysis fitted well test data in high-cycle region as well as ones in low-cycle region.

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