The Effects of Induction Heating Conditions on Controlling Residual Stresses in Welded Pipes

1982 ◽  
Vol 104 (4) ◽  
pp. 267-273 ◽  
Author(s):  
E. F. Rybicki ◽  
P. A. McGuire
Keyword(s):  
Residual Stresses ◽  
Induction Heating ◽  
Outer Surface ◽  
304 Stainless Steel ◽  
Residual Stress State ◽  
Surface Temperatures ◽  
Inner Surface ◽  
Induced Stresses ◽  
Welded Pipe ◽  
Type 304

Induction heating for stress improvement (IHSI) is a method for reducing the tensile weld induced stresses on the inner surfaces of the girth welded pipes. The process entails inductively heating the outside of a welded pipe while cooling the inner surface with flowing water. A 10-in. Schedule 80 Type 304 stainless steel pipe was selected for this study. Residual stresses due to welding were first determined using a finite element computational model. Several IHSI treatments subsequent to welding are then examined computationally to determine the effect of induction coil length and maximum outer surface temperatures on the final residual stress state. All IHSI treatments gave reduced inside surface tensile weld induced stresses on the inner surface. Longer coils and higher outer surface temperatures led to inner surface stresses that were more compressive.

A Computational Model for Improving Weld Residual Stresses in Small Diameter Pipes by Induction Heating

1981 ◽  
Vol 103 (3) ◽  
pp. 294-299 ◽  
Author(s):  
E. F. Rybicki ◽  
P. A. McGuire
Keyword(s):  
Residual Stresses ◽  
Induction Heating ◽  
Laboratory Data ◽  
Small Diameter ◽  
Computational Results ◽  
Computational Capability ◽  
Inner Surface ◽  
Girth Welding ◽  
Welded Pipe ◽  
Compressive Residual Stresses

Girth welding can produce tensile residual stresses on the pipe inner surface. Because tensile stresses enhance the possibility of stress corrosion cracking, methods for altering the weld-induced stress state are being investigated. One method, Induction Heating for Stress Improvement (IHSI), involves induction heating the pipe while cooling the inner surface. The method is being evaluated using both experimental and computational studies. This paper presents computational results of a 101.66-mm (4-in.) Schedule 80 stainless steel pipe. Results include comparisons of computed values for residual stresses with laboratory data. Computed values of residual stresses and laboratory data are in agreement and, for this case, clearly show that the IHSI process can change weld-induced tensile residual stresses to compressive values. A comparison of computational results for applying the IHSI process to a stress-free pipe and a welded pipe indicate that for geometry and process parameters considered here, the IHSI-induced compressive residual stresses on the pipe inner surface for these two cases are similar. The experimental results presented here show the feasibility of controlling weld-induced residual stresses. The computational results demonstrate a capability for predicting the observed stress behavior. The computational capability then provides an efficient tool to aid in developing ways for controlling residual stresses for other pipe sizes and weldment geometries.

scholarly journals Residual Stress State of X65 Pipeline Girth Welds Before and After Local and Furnace Post Weld Heat Treatment

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Yao Ren ◽  
Anna Paradowska ◽  
Bin Wang ◽  
Elvin Eren ◽  
Yin Jin Janin
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Post Weld Heat Treatment ◽  
Pipe Length ◽  
Stress Profiles ◽  
Girth Welds ◽  
Welded Pipe ◽  
Weld Heat

This research investigated the effects of global (in other words, furnace-based) and local post weld heat treatment (PWHT) on residual stress (RS) relaxation in API 5L X65 pipe girth welds. All pipe spools were fabricated using identical pipeline production procedures for manufacturing multipass narrow gap welds. Nondestructive neutron diffraction (ND) strain scanning was carried out on girth welded pipe spools and strain-free comb samples for the determination of the lattice spacing. All residual stress measurements were carried out at the KOWARI strain scanning instrument at the Australian Nuclear Science and Technology Organization (ANSTO). Residual stresses were measured on two pipe spools in as-welded condition and two pipe spools after local and furnace PWHT. Measurements were conducted through the thickness in the weld material and adjacent parent metal starting from the weld toes. Besides, three line-scans along pipe length were made 3 mm below outer surface, at pipe wall midthickness, and 3 mm above the inner surface. PWHT was carried out for stress relief; one pipe was conventionally heat treated entirely in an enclosed furnace, and the other was locally heated by a flexible ceramic heating pad. Residual stresses measured after PWHT were at exactly the same locations as those in as-welded condition. Residual stress states of the pipe spools in as-welded condition and after PWHT were compared, and the results were presented in full stress maps. Additionally, through-thickness residual stress profiles and the results of one line scan (3 mm below outer surface) were compared with the respective residual stress profiles advised in British Standard BS 7910 “Guide to methods for assessing the acceptability of flaws in metallic structures” and the UK nuclear industry's R6 procedure. The residual stress profiles in as-welded condition were similar. With the given parameters, local PWHT has effectively reduced residual stresses in the pipe spool to such a level that it prompted the thought that local PWHT can be considered a substitute for global PWHT.

scholarly journals Improving the Inner Surface State of Thick-Walled Tubes by Heat Treatments with Internal Quenching Considering a Simulation Based Optimization

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1303
Author(s):  
Fabian Mühl ◽  
Moritz Klug ◽  
Stefan Dietrich ◽  
Volker Schulze
Keyword(s):  
Heat Treatment ◽  
Residual Stresses ◽  
Surface State ◽  
Treatment Process ◽  
Treatment Method ◽  
Fe Model ◽  
Heat Treatment Process ◽  
Residual Stress State ◽  
Optimization Study ◽  
Inner Surface

Internal Quenching is an innovative heat treatment method for difficult to access component sections. Especially, the microstructure, as well as the residual stress state at inner surfaces, of thick-walled tubes can be adjusted with the presented flexible heat treatment process. Based on multiphysical FE-models of two different steels, a simulative optimization study, considering different internal quenching strategies, was performed in order to find the optimal cooling conditions. The focus hereby was on the adjustment of a martensitic inner surface with high compressive residual stresses. The simulatively determined optimal cooling strategies were carried out experimentally and analyzed. A good agreement of the resulting hardness and residual stresses was achieved, validating the presented Fe-model of the Internal Quenching process. The shown results also indicate that the arising inner surface state is very sensitive to the transformation behavior of the used steel. Furthermore, the presented study shows that a preliminary simulative consideration of the heat treatment process helps to evaluate significant effects, reducing the experimental effort and time.

scholarly journals Residual Stresses Induced by Surface Working and Their Improvement by Emery Paper Polishing

2020 ◽  
Vol 4 (2) ◽  
pp. 21
Author(s):  
Makoto Hayashi
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Diffraction Method ◽  
304 Stainless Steel ◽  
Heat Treated ◽  
Emery Paper ◽  
Type 304 ◽  
Type 304 Stainless Steel

In many of machine parts and structural components, materials surface would be worked. In this study, residual stresses on the surfaces were measured by X-ray diffraction method, and effects of surface working on the residual stresses were examined. In case of lathe machining of type 304 stainless steel bar, the residual stresses in circumferential directions are tensile, and those in axial directions are almost compressive. Highly tensile residual stresses in the circumferential directions were improved by emery paper polishing. 10 to 20 times of polishing changes high tensile residual stresses to compressive residual stresses. In the case of shot peening on a type 304 stainless steel plate, the compressive residual stress inside is several hundred MPa lower than that on the surface. By applying the emery paper polishing to the shot peened surface 10 or 20 times, the residual stress on the surface is improved to −700 MPa. While fatigue strength at 288 °C in the air of the shot peened material is 30 MPa higher than solution heat treated and electro-polished material, the fatigue strength of the shot peened and followed by emery paper polished material is 60 MPa higher. Thus, the emery paper polishing is simple and a very effective process for improvement of the residual stresses.

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.

Residual Stress Measurement in 304 Stainless Steel Weld Overlay Pipes

1996 ◽  
Vol 118 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Hung-Ju Yen ◽  
Mark Ching-Cheng Lin ◽  
Lih-Jin Chen
Keyword(s):  
Residual Stress ◽  
Compressive Residual Stress ◽  
Stress Measurement ◽  
Residual Stress Distribution ◽  
304 Stainless Steel ◽  
Steel Weld ◽  
Weld Overlay ◽  
Stainless Steel Weld ◽  
Inner Surface ◽  
Welded Pipe

Welding overlay repair (WOR) is commonly employed to rebuild piping systems suffering from intergranular stress corrosion cracking (IGSCC). To understand the effects of this repair, it is necessary to investigate the distribution of residual stresses in the welded pipe. The overlay welding technique must induce compressive residual stress at the inner surface of the welded pipe to prevent of IGSCC. To understand the bulk residual stress distribution, the stress profile as a function of location within wall is examined. In this study the full destructive residual stress measurement technique—a cutting and sectioning method—is used to determine the residual stress distribution. The sample is type 304 stainless steel weld overlay pipe with an outside diameter of 267 mm. A pipe segment is cut from the circular pipe; then a thin layer is removed axially from the inner to the outer surfaces until further sectioning is impractical. The total residual stress is calculated by adding the stress relieved by cutting the section away to the stress relieved by axially sectioning. The axial and hoop residual stresses are compressive at the inner surface of the weld overlay pipe. Compressive stress exists not only at the surface but is also distributed over most of the pipe’s cross section. On the one hand, the maximum compressive hoop residual stress appears at the pipe’s inner surface. The magnitude approaches the yield strength of the material; the compressive stress exists from the inner surface out to 7.6 mm (0.3 in.) radially. On the other hand, compressive axial residual stress begins at depths greater than 2.5 mm (0.1 in.); its maximum value is located at 10.7 mm (0.42 in.) with magnitude close to four-tenths of yield strength. The thermal-mechanical induced crack closure from significant compressive residual stress is discussed. This crack closure can thus prevent IGSCC very effectively.

scholarly journals Residual Stress State of X65 Pipeline Girth Welds Before and After Local and Furnace Post Weld Heat Treatment

2016 ◽  
Author(s):  
Yao Ren ◽  
Anna Paradowska ◽  
Bin Wang ◽  
Elvin Eren
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Residual Stresses ◽  
Outer Surface ◽  
Post Weld Heat Treatment ◽  
Stress Profiles ◽  
Stress States ◽  
Girth Welds ◽  
Welded Pipe ◽  
Weld Heat

This research investigated the effects of global (in other words, furnace-based) and local post weld heat treatment (PWHT) on residual stress (RS) relaxation in API 5L X65 pipe girth welds. Two pipe spools were fabricated using identical pipeline production procedures for manufacturing multi-pass narrow gap welds. Non-destructive neutron diffraction strain scanning was carried out on girth welded pipe spools and stress-free comb samples and also thin slices for the determination of lattice spacing. All residual stress measurements were carried out at the KOWARI strain scanning instrument at the Australian Nuclear Science and Technology Organization (ANSTO). Residual stresses of two pipe spools (in the as-welded condition) were measured through the thickness in the weld material and adjacent parent metal starting from the weld toe. Three line-scans were completed 3mm below outer surface, at mid thickness and 3mm above the inner surface. PWHT was adopted for stress relaxation; one pipe was conventionally heat treated entirely in an enclosed furnace and the other was locally heated by a flexible ceramic heating pad. Residual stresses were measured after PWHT at exactly the same locations as those used for the as-welded condition. Residual stress states of the two pipe spools in as-welded condition and after PWHT were compared and the results were presented in full stress maps. Additionally, through thickness residual stress profiles and the results of one line scan (3mm below outer surface) were compared with the respective residual stress profiles advised in British Standard BS 7910 “Guide to methods for assessing the acceptability of flaws in metallic structures” and the UK nuclear industry’s R6 procedure. The residual stress states of the two pipe spools measured in the as-welded condition were similar. With the given parameters, local PWHT has effectively reduced residual stresses in the pipe spool to such a level that it prompted the thought that local PWHT can be considered a substitute for global PWHT.

Failure Mechanisms of Equal and Unequal Wall Thickness Hybrid Maraging Steel-P20 Tubular Joints: Effects of Welding Residual Stresses

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Alireza Ebrahimi ◽  
Shawn Kenny ◽  
Mohsen Mohammadi
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Maraging Steel ◽  
Wall Thickness ◽  
Mechanical Performance ◽  
Fe Modeling ◽  
Residual Stress State ◽  
Welded Pipe ◽  
Pipe Joint

Abstract Joining an additively manufactured component to a forged or cast part through welding processes has recently attracted the attention of engineers and scientists. This technique integrates the technical benefits of additive manufacturing (AM) technology with conventional processes that may be more cost-efficient. In this paper, the effect of residual stresses on the mechanical performance of a hybrid welded pipe joint connecting an additively manufactured maraging steel (MS1) pipe segment with a conventional P20 steel tube having an equivalent outside diameter was studied. A sequentially coupled thermo-mechanical continuum finite element (FE) modeling procedure to predict the residual stress state on circumferential pipe hybrid MS1-P20 joints subjected to multi-axial loads was developed and validated. Available experimental data on a welded pipe joint with conventional stainless steel (SUS304) were used to calibrate the model. The FE modeling procedures were further validated for the hybrid MS1-P20 joint. The predicted residual stress state was mapped on the pipe joint with equal and unequal wall thickness joint transitions. The mechanical performance of these pipe joints was evaluated with the application of internal pressure, uniaxial tension, and flexural loads. The major contribution of this study was the proposition of a new concept of hybrid joints, where a significant transition of the load was expected. The new hybrid joint concept was presented to meet the existing design criteria requirements without sacrificing other parameters (e.g., component weight and manufacturing expense) and facilitate the production of hybrid components using AM techniques.

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