Residual-Stress, Material Characterization in P22 HRSG-Pipeline Butt Joint

2020 ◽  
Author(s):  
Ottaviano Grisolia ◽  
Lorenzo Scano ◽  
Francesco Piccini ◽  
Antonietta Lo Conte ◽  
Massimiliano De Agostinis ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Level ◽  
Outer Surface ◽  
High Stress ◽  
Base Material ◽  
Longitudinal Direction ◽  
Tangential Direction ◽  
Butt Joint ◽  
Hole Drilling ◽  
Plane State

Abstract Previous study evaluated residual stress in a circumferential “V”-groove butt joint of a heat-recovery steam generator (HRSG) pipeline; the material was ASTM A-335-Grade P22. Aim had been to check on the influence over creep-relaxation previously found out for a tee made of the same material. The butt joint had been operating for the same period of 200,000 hours, same temperature of 528°C at almost a half pressure (0.46 Kg/mm2 vs. 1.06 Kg/mm2). X-ray diffraction (XRD) technique applied close to the weld highlighted anomalously high stress-level on the outer surface for all four butt-joint samples tested. Residual-stress over 400 MPa observed along the cylinder’s tangential direction was statically not acceptable. On the inner surface where deposited beads may have tempered adjacent base material, measurement via blind hole-drilling (BHD) technique showed a symmetrical plane-state residual-stress of 199 MPa. It was consistent with that observed via XRD on the outer surface in the cylinder’s longitudinal direction. Supposing a case of incomplete post heating planned for the weld may have explained the occurrence of being much higher than 40 MPa, value predicted after 200,000 hours. Similar influence over creep results found out for the tee and the butt joint had validated modeling welding simulation considered for both joints. A comprehensive new series of XRD tests aims now at measuring residual stress across the cylinder’s wall, both inner and outer sides. The shallow layer considered has thickness sufficient for building a map of measurements covering different depths and locations on the surface. The experimental plan includes also BHD tests supporting the XRD ones. Comparison with previous measurements roughly shows stress level increasing similarly across the cylinder’s wall from the inner side on: Average stress values, however, appear lower than previous measurements, showing better compatibility to the analysis results.

Effects of Pipe Dimensions and Outer Surface-Buttering Weld Conditions on Residual Stress Distributions

2008 ◽  
Author(s):  
Nobuyoshi Yanagida
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Hoop Stress ◽  
Axial Stress ◽  
Butt Joint ◽  
Stress Distributions ◽  
The Finite Element Method ◽  
Butt Joints ◽  
Inner Surface

Effects of pipe dimensions and outer surface-buttering weld conditions on residual stress distributions were evaluated using the finite element method. Residual stresses were analyzed for 508–mm-diameter (500A) pipe 38.1 mm thick, 508–mm-diameter (500A) pipe 15.1 mm thick, and 267–mm-diameter (250A) pipe 15.1 mm thick. After the residual stresses at pipe butt joints were analyzed, residual stresses at these joints subjected to the outer surface-buttering welds were analyzed. Residual stresses were determined for various weld widths, thicknesses, and heat inputs. These analyses indicate that tensile axial stress occurred at inner surface of the pipe butt joint and that it decreased with increasing the outer surface buttering-weld width or heat input. They also indicate that compressive hoop stress occurred at inner surface of the joint and that outer surface-buttering weld increased it. The outer surface-buttering weld conditions that generate compressive residual stress at the inner surface of the pipe butt joints were determined.

The Effect of Boring After Autofrettage of Pressure Cylinders

2009 ◽  
Author(s):  
G. H. Majzoobi ◽  
A. H. Mahmoudi ◽  
S. Zahirnia
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Outer Surface ◽  
Stress Measurement ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Numerical Predictions ◽  
Inner Surface ◽  
Von Mises ◽  
Hoop Stresses

In this work, the effect of boring on residual stress distribution in thick walled pressure cylinders after autofrettage is studied by numerical simulation using finite element method. Autofrettage is performed using mandrelling technique. The simulations are validated by experiment. In this regard, some cylinders are autofrettaged through mandrelling technique and residual stress is measured using central hole drilling method. The simulation of boring is performed by removing elements of cylindrical layers of small thickness after the loading and unloading processes (autofrettage) are completed. The diametral interferences of 0.4 mm and 0.6 mm between the mandrel and the cylinder are considered for the simulations. The results indicate that boring increases the through thickness residual Von-Mises and compressive hoop stresses from the inner surface up to a certain radius thereafter the trend changes and the stresses begin to reduce. Boring has reducing effect on radial stress distribution across the wall of the cylinder. Since residual stress measurement on the inner surface of the cylinder is difficult, the measurements are made only on the outer surface of the vessel. A good agreement between the trend of numerical predictions and experimental results are observed for boring. On the whole, boring can increase the residual stress at the inner surface and reduce it at the outer surface of pressure cylinder.

The Influence of Chemical Composition on Residual Stresses in NiCoMo Alloy Deposits on 12 Ni Maraging Steel

2013 ◽  
Vol 768-769 ◽  
pp. 449-455 ◽  
Author(s):  
Zoran Bergant ◽  
Janez Grum
Keyword(s):  
Residual Stress ◽  
Chemical Composition ◽  
Residual Stresses ◽  
Base Material ◽  
Stress Generation ◽  
Hole Drilling ◽  
Residual Stress Field ◽  
Hole Drilling Method ◽  
Similar Chemical ◽  
Drilling Method

The in-plane residual stresses in laser cladded specimens, made of 12-nickel precipitation hardening maraging hot-working tool steel 1.2799 (SIST EN 10027-2) are analyzed using the hole drilling method. The CO2 laser was used to deposit the alloy NiCoMo-1 with significantly higher content of nickel and cobalt with austenitic microstructure at room temperature. The Nd:YAG laser was used to deposit the maraging alloy designated NiCoMo-2, with similar chemical composition as the base material. The comparison of residual stress field showed the sign and the magnitude of residual stresses depends on the chemical composition of the clad being deposited. The high tensile residual stresses were found in NiCoMo-1 layers and favorable compressive residual stresses were found in NiCoMo-2 layers. The metallurgical aspects of residual stress generation are discussed.

Study of Nonuniform In-Plane and In-Depth Residual Stress of Friction Stir Welding

2003 ◽  
Vol 125 (2) ◽  
pp. 201-208 ◽  
Author(s):  
Min Ya ◽  
Fulong Dai ◽  
Jian Lu
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Stress Gradient ◽  
High Stress ◽  
Hole Drilling ◽  
Friction Stir ◽  
Hole Drilling Method ◽  
Incremental Hole Drilling ◽  
Longitudinal Residual Stress ◽  
Drilling Method

Friction stir welding (FSW) is a newly developed welding technique that can join aluminum alloys of low fusion weldability. The conventional hole-drilling method does not consider the nonuniform in-plane stress around the drilled hole, it is no longer valid for the residual stress of FSW which has high stress gradient. However, assuming the relaxation of in-plane nonuniform residual stress to be uniform on a small increment of the boundary of the hole, the recently developed Moire´ interferometry incremental hole-drilling (MIIHD) method can be used. Residual stress of a thin plate of friction stir welded aluminum alloy was studied by MIIHD. The longitudinal residual stress distribution in the transversal direction and through the thickness was obtained and compared with results by strain gage method.

The Fatigue Properties of Laser Shock Processed Aluminum Alloy 7050

2007 ◽  
Author(s):  
Shikun Zou ◽  
Ziwen Cao
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
Fatigue Life ◽  
Plastic Strain ◽  
Base Material ◽  
Fatigue Properties ◽  
Hole Drilling ◽  
Drilling Process ◽  
Laser Peening ◽  
Laser Shock

In order to develop the application of laser shock processing (also named laser peening or LSP in short) as a strengthening technology for 7050 aluminum alloy fastener holes, the fatigue properties of laser shock-processed aluminum alloy specimens were investigated. At first, the dislocation density and surface residual stress induced in the shock affected zone was characterized and compared with that of the base material. Then, the fatigue specimens with stress-concentration hole (notch) were treated by LSP. The fatigue life of LSP-treated specimens were measured and compared with that of specimens made from base material without LSP. Fatigue tests were taken under special flight spectrum loading condition for mid-airframe. The results indicated that laser peening improved the fatigue life of all specimens tested. Specimens treated by LSP before hole-drilling had longer fatigue life than those specimens treated by LSP after hole-drilling. At last, the difference of both sequences was investigated by analyzing the plastic strain and residual stress induced by LSP. LSP induced both plastic strain and deformation at the surface layer. The plastic strain induced by LSP was shown to produce harmful orifices with sharp-angle near the edge of hole. The residual stress induced by LSP appears to remain compressive even after the hole-drilling process. In average, the fatigue life of specimens treated by LSP before hole-drilling was found to be 173% longer than that of untreated samples and approaching the life enhancement factor demonstrated by rod extrusion method (on specimens with large diameter holes).

Residual Stresses Determination near FSW Joints by Combining the Hole Drilling Method and Reflection Hologram Interferometry

2021 ◽  
Vol 1037 ◽  
pp. 251-257
Author(s):  
Andrey V. Chernov ◽  
Igor N. Odintsev ◽  
Vladimir S. Pisarev
Keyword(s):  
Residual Stress ◽  
Local Deformation ◽  
Butt Joint ◽  
Hole Drilling ◽  
Friction Stir ◽  
Hole Drilling Method ◽  
Tool Shoulder ◽  
Stress Components ◽  
Reflection Hologram ◽  
Hologram Interferometry

The results of residual stress characterization near friction stir welded (FSW) butt joint of aluminum plates are reported. The experimental analysis employs two-side measurements of local deformation response on small hole drilling by reflection hologram interferometry. The approach developed is based on the unequivocally solution of the properly posed inverse problem thus deriving both membrane and bending residual stress components. Residual stress components of high level are derived inside the tool shoulder borders on both specimen faces.

A brief Survey of Assessment models to Predict stress Level of Heavy Metals in Soils

2020 ◽  
Vol 13 ◽  
Author(s):  
Sangeetha Annam ◽  
Anshu Singla
Keyword(s):  
Economic Growth ◽  
Heavy Metals ◽  
Heavy Metal ◽  
Ecological Risk ◽  
Stress Level ◽  
Metal Contamination ◽  
Heavy Metal Contamination ◽  
Human Life ◽  
High Stress ◽  
Heavy Metal Stress

Abstract: Soil is a major and important natural resource, which not only supports human life but also furnish commodities for ecological and economic growth. Ecological risk has posed a serious threat to the ecosystem by the degradation of soil. The high-stress level of heavy metals like chromium, copper, cadmium, etc. produce ecological risks which include: decrease in the fertility of the soil; reduction in crop yield & degradation of metabolism of living beings, and hence ecological health. The ecological risk associated, demands the assessment of heavy metal stress levels in soils. As the rate of stress level of heavy metals is exponentially increasing in recent times, it is apparent to assess or predict heavy metal contamination in soil. The assessment will help the concerned authorities to take corrective as well as preventive measures to enhance the ecological and hence economic growth. This study reviews the efficient assessment models to predict soil heavy metal contamination.

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