HRSG-Pipeline Weld Residual-Stress Measurement to Assess Influence Over Creep-Analysis Results From Italian Code, American Standard

2019 ◽  
Author(s):  
Ottaviano Grisolia ◽  
Lorenzo Scano ◽  
Francesco Piccini ◽  
Antonietta Lo Conte ◽  
Massimiliano De Agostinis ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Measurement ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Welding Process ◽  
Diffraction Method ◽  
Hole Drilling ◽  
Creep Analysis ◽  
Maximum Residual Stress ◽  
American Standard

Abstract Previous study carried out residual stress characterization for the welds of the high-temperature-section (superheater / reheater) lower headers of the bottom-supported heat-recovery steam generator (HRSG). Modeling the gas-tungsten arc, manual welding process considered only weld-lay for the ASTM A 335-Grade P22 finned-tube angle joint to the cylinder. Present study aims at indirectly assessing findings of previous analysis measuring maximum residual stress on the joint’s exservice material. To achieve that a tee similar to the previous was not available: for both experimental and numerical analyses present study considers a P22 circumferential “V”-groove butt joint on HRSG pipeline section, creep-operated for the same period and temperature as the previous case. In the experimental activity X-ray diffraction method (or alternatively, hole-drilling strain gage one) applies as close as possible to the weld, being residual stress maximum at the fusion boundary. Thermal analysis for the previous case also showed it keeps nearly constant during weld cooling, relaxing most during creep: after 200,000 hours of operation, welding-process simulation predicted a maximum residual stress of 70 MPa; tee-joint creep-analysis found out a maximum equivalent stress of 91 MPa. As for the sample withdrawal, dimensions should be sufficient to avoid any interference with measurement area. The experimental procedures should comply with the European standard EN 15305 on the matter (the American standard ASTM E 837 for the alternate method). Comparison of analysis results for the two cases, confirms tendencies previously found out in creep-behavior, though different equivalent stress contributions. Comparison of predicted and observed residual stress values should allow for validation of numerical models used in both welding process and stress analysis.

Post Welding Heat Treatment Simulation in Welded Stainless Steel Pipe and Comparison with Experiment

2009 ◽  
Vol 83-86 ◽  
pp. 237-243
Author(s):  
Mohammad Sedighi ◽  
B. Davoodi
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stainless Steel ◽  
Stress Distribution ◽  
Numerical Models ◽  
Welding Process ◽  
Steel Pipe ◽  
Hole Drilling ◽  
Distribution Data ◽  
Stainless Steel Pipe

Due to the intense concentration of heat in the welding process, residual stresses are produced in the specimen. One of the most effective ways to relief welding stress is Post Welding Heat Treatment (PWHT). In this paper, finite element method is employed to model and analyze PWHT for two pass butt-welded SUS304 stainless steel pipe. In this simulation, firstly, the welding process has been modeled. Then the stress distribution of the specimen has been transferred to a second analysis for stress relaxation modeling. Norton law is used to investigate creep in stress relief process. Experimental tests are also carried out to verify the effectiveness of the proposed numerical models. The hole drilling method is used to measure the stress distribution in the specimen. The residual stress distribution data before and after PWHT are compared to investigate the effect of heat treatment on residual stress. Based on the modeling and experimental results, the tensile and compressive stresses distributions have been reduced. They are in a reasonable agreement with each other and prove the capability of the proposed modeling technique to simulate PWHT.

Evaluate welding residual of 6082-T6 aluminum alloy welded plate by using ultrasonic method

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940038
Author(s):  
Zhongyin Zhu ◽  
Guoqing Gou ◽  
Zhiyi Zhang ◽  
Chuanping Ma ◽  
Wei Gao
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Ultrasonic Method ◽  
Welding Process ◽  
Diffraction Method ◽  
Element Model ◽  
Hole Drilling ◽  
X Ray Diffraction ◽  
Effective Depth ◽  
Good Agreement

The residual stress beneath the surface is crucial to the safety of the structures. Neutron Diffraction and Hole-drilling are the two methods being used to measure the inner residual stress. Longitudinal Critically Refracted (LCR) wave transmission that is propagated parallel to surface also can be used for measuring residual stress, but measurements are within an effective depth and need to be further studied. In this paper, the parameters of K are separately tested in WZ, HAZ and BM zone. The welding process of 6082-T6 aluminum alloy welded joints is simulated in SYSWELD, the finite element model has been verified by the X-ray diffraction method. The residual stress value calculated by SYSWELD and the values obtained from the ultrasonic measurement show a good agreement. It is demonstrated that the residual stress of 6082-T6 aluminum alloy welded plate can be evaluated by using the ultrasonic method.

The Experimental Study of Diffraction Angle of Aluminum Alloy 3003

2012 ◽  
Vol 625 ◽  
pp. 291-296
Author(s):  
Neng Quan Duan ◽  
Jian Liang Ren ◽  
Rui Qiang Pang
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Stress Measurement ◽  
Electrical Measuring ◽  
Diffraction Method ◽  
Measuring Method ◽  
X Ray ◽  
Equal Strength ◽  
Diffraction Angle ◽  
Stress Measuring

The most suitable diffraction angle of aluminum alloy 3003 used for stress measuring is aimed to be determined in this paper. The experiment makes a stress measurement of a loading aluminum alloy 3003 equal strength beam with the traditional electrical measuring method and the X-ray stress measurement. With the electrical measuring method as reference, the research study the measured values that acquired from the X-ray diffraction method when the diffraction angle are 142° and 156°, and then compare them with that acquired from electrical measuring method. The measurement results demonstrate that the diffraction angle at 156 ° is better than at 142 ° based on the assessment standards of the liner slope and the distribution of data. Thus the optimum diffraction angle for X-ray to measure the macroscopic stress of aluminum alloy 3003 is 156 °. In this paper，the stress caused by the load on the equal strength beam is assumed to be "residual stress" and thus the conclusion has reference values for the standardization of residual stress measurement of aluminum alloy by XRD and has theoretical guiding significance in the production practices.

Residual Stress Prediction by Means of 3D FEM Simulation

2011 ◽  
Vol 223 ◽  
pp. 431-438 ◽  
Author(s):  
Aldo Attanasio ◽  
Elisabetta Ceretti ◽  
Cristian Cappellini ◽  
Claudio Giardini
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Stress Measurement ◽  
Numerical Models ◽  
Orthogonal Cutting ◽  
Residual Stress Distribution ◽  
Tool Geometry ◽  
Distribution Analysis ◽  
3D Fem ◽  
Workpiece Material

In cutting field, residual stress distribution analysis on the workpiece is a very interesting topic. Indeed, the residual stress distribution affects fatigue life, corrosion resistance and other functional aspects of the workpiece. Recent studies showed that the development of residual stresses is influenced by the cutting parameters, tool geometry and workpiece material. For reducing the costs of experimental tests and residual stress measurement, analytical and numerical models have been developed. The aim of these models is the possibility of forecasting the residual stress distribution into the workpiece as a function of the selected process parameters. In this work the residual stress distributions obtained simulating cutting operations using a 3D FEM software and the corresponding simulation procedure are reported. In particular, orthogonal cutting operations of AISI 1045 and AISI 316L steels were performed. The FEM results were compared with the experimental residual stress distribution in order to validate the model effectiveness.

scholarly journals Efficiency of Plasticity Correction in the Hole-Drilling Residual Stress Measurement

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3396
Author(s):  
Tomáš Návrat ◽  
Dávid Halabuk ◽  
Petr Vosynek
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Uniaxial Tension ◽  
Relative Error ◽  
Computational Simulation ◽  
Equivalent Stress ◽  
Biaxial Stress ◽  
Hole Drilling ◽  
Plane Shear ◽  
Plasticity Effect

This paper focuses on the analysis of the plasticity effect in the measurement of the residual stress by the hole-drilling method. Relaxed strains were evaluated by the computational simulation of the hole-drilling experiment using the finite element method. Errors induced by the yielding were estimated for uniaxial tension, plane shear stress state and equi-biaxial stress state at various magnitudes of residual stress uniformly distributed along the depth. The correction of the plasticity effect in the evaluation of residual stress was realized according to the method proposed by authors from the University in Pisa, which was coded in MATLAB. Results obtained from the MATLAB script were compared to the original input data of the hole-drilling simulation and discussed. The analyses suggested that the plasticity effect is negligible at the ratio of applied equivalent stress to yield stress, being 0.6, and that the correction of the plasticity effect is very successful at the previous ratio, being 0.9. Failing to comply with the condition of the strain gauge rosette orientation according to the principal stresses directions causes an increase in the relative error of corrected stresses only for the case of uniaxial tension. It affects the relative error negligibly for the plane shear and equi-biaxial stress states.

Dual-Axis Hole-Drilling ESPI Residual Stress Measurements

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Gary S. Schajer ◽  
Michael Steinzig
Keyword(s):  
Residual Stress ◽  
Measurement Errors ◽  
Measurement Method ◽  
Stress Measurement ◽  
Experimental Tests ◽  
Optical Data ◽  
Hole Drilling ◽  
Similar Response ◽  
Plane Normal ◽  
Stress Components

A novel dual-axis ESPI hole-drilling residual stress measurement method is presented. The method enables the evaluation of all the in-plane normal stress components with similar response to measurement errors, significantly lower than with single-axis measurements. A numerical method is described that takes advantage of, and compactly handles, the additional optical data that are available from the second measurement axis. Experimental tests were conducted on a calibrated specimen to demonstrate the proposed method, and the results supported theoretical expectations.

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