A Study of Cyclic Thermal Straining in a Welded Joint, Using a Closed-Loop, Servo-Controlled Testing Machine

1992 ◽  
Vol 114 (4) ◽  
pp. 422-427 ◽  
Author(s):  
Y. Z. Itoh ◽  
H. Kashiwaya
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Thermal Stress ◽  
Residual Stresses ◽  
Closed Loop ◽  
Thermal Stresses ◽  
Testing Machine ◽  
Step Test ◽  
Transient Thermal ◽  
Incremental Step

For investigating the origin of residual stresses in welded joints, the transient thermal stresses in a carbon-manganese-silicon steel (JIS SM41B), a cast martensitic stainless steel (JIS SCS5), an austenitic stainless steel (JIS SUS304), and a titanium alloy (Ti-6Al-4V) were investigated by subjecting round bar specimens, in which both ends were fixed, to thermal of cycles. The specimens were heated in air by high-frequency induction. The cyclic thermal straining tests were conducted for the case of a single thermal cycle and the case of multiple thermal cycles, using a closed loop, servo-controlled testing machine. The experimental results made clear that the transient thermal stress behavior was dependent on metallurgical effects, such as phase transformations, strain hardening, the Bauschinger effect, etc. The effects on phase transformation on the transient thermal stress behavior of SCS5 and SM41B were especially remarkable. However, the effects of phase transformations on the residual stresses due to the thermal straining cycle were negligible in SM41B and not observed in both SUS304 and Ti-6Al-4V. The residual stresses tended to increase with increase of the peak temperature of thermal cycles in SM41B, SUS304 and Ti-6Al-4V. However, when the peak temperature increased above 600°C in SCS5, the residual stress rapidly decreased and became compressive because of the expansion due to the martensite transformation. This study led to the conclusion that the transient thermal stresses for various peak temperatures could easily be obtained by an incremental step test using a single specimen and that this incremental step test could simply estimate the residual stress character of butt-welded joints.

Development of Residual Stress Improvement for Nuclear Pressure Vessel Instrumentation Nozzle Weld Joint (P-43+P-8) by Means of Induction Heating

2006 ◽  
Author(s):  
Takuro Terajima ◽  
Takashi Hirano
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Residual Stresses ◽  
Induction Heating ◽  
Weld Joint ◽  
Thermal Stresses ◽  
Pressure Vessels ◽  
Weld Joints

As a counter measurement of intergranular stress corrosion cracking (IGSCC) in boiling water reactors, the induction heating stress improvement (IHSI) has been developed as a method to improve the stress factor, especially residual stresses in affected areas of pipe joint welds. In this method, a pipe is heated from the outside by an induction coil and cooled from the inside with water simultaneously. By thermal stresses to produce a temperature differential between the inner and outer pipe surfaces, the residual stress inside the pipe is improved compression. IHSI had been applied to weld joints of austenitic stainless steel pipes (P-8+P-8). However IHSI had not been applied to weld joints of nickel-chromium-iron alloy (P-43) and austenitic stainless steel (P-8). This weld joint (P-43+P-8) is used for instrumentation nozzles in nuclear power plants’ reactor pressure vessels. Therefore for the purpose of applying IHSI to this one, we studied the following. i) Investigation of IHSI conditions (Essential Variables); ii) Residual stresses after IHSI; iii) Mechanical properties after IHSI. This paper explains that IHSI is sufficiently effective in improvement of the residual stresses for this weld joint (P-43+P-8), and that IHSI does not cause negative effects by results of mechanical properties, and IHSI is verified concerning applying it to this kind of weld joint.

Residual Stress Simulation of Stud Welding in a Rectangular Steel Tubular Surface

2010 ◽  
Vol 44-47 ◽  
pp. 581-585
Author(s):  
Lei Wang ◽  
Qi Lin Zhang ◽  
Lu Chen
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Thermal Stresses ◽  
Three Dimensional ◽  
Element Model ◽  
Stud Welding ◽  
Tubular Surface ◽  
Three Dimensional Models ◽  
Transient Thermal ◽  
Stress Simulation

A thermal-mechanical coupled finite element model has been presented to predict residual and thermal stresses during different stages of stud welding. The finite study was carried out using three-dimensional models. To enhance the accuracy of the numerical solution material properties including physical, thermal and mechanical properties supposed to be temperature-dependent. After the temperature distributions as a result of welding were calculated, thermal and residual stress values obtained. Residual stresses are attributed to the elasto-plastic response of the object towards the transient thermal stresses generated by the welding. After all temperature values reach the room temperature, the residual stresses decrease to a small value.

Characterising Residual Stresses in Rectangular Beam Specimens Following Thermo-Mechanical Loading

2006 ◽  
Author(s):  
Ali Mirzaee-Sisan ◽  
Christopher E. Truman ◽  
David J. Smith
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stainless Steel ◽  
Stress Field ◽  
Residual Stresses ◽  
Mechanical Loading ◽  
Ferritic Steel ◽  
Thermal Stresses ◽  
Residual Stress Field ◽  
Rectangular Beam

The neutron diffraction (ND) technique was used to characterise residual stress fields in thin rectangular beam specimens containing residual stresses induced thermo-mechanically by partial quenching. Two types of material were considered, type 316H stainless steel and A533B ferritic steel. The work was motivated by a need to investigate the influence of residual stress on the fracture behaviour of steels. During quenching, specimens experienced a severe temperature gradient which induced thermal stresses resulting in plastic strains and a subsequent residual stress field. An extensive finite element (FE) analysis was undertaken to predict the residual stress following thermo-mechanical loading. It was shown that partial quenching generated a considerable residual stress field in 316H stainless steel. However, the level of residual stresses in the A533B steel specimens was lower than that 316H stainless steel specimens. There was acceptable agreement between the finite element simulations and measurements with simulations generally predicting higher tensile residual stresses following partial quenching than those measured in the 316H stainless steel, and lower tensile residual stresses than those measured in the A533B ferritic steel.

Modeling and Measurement of Residual Stresses in a Steel Vessel Containing Glass

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
S. Nakhodchi ◽  
B. G. Thomas ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Thermal Stress ◽  
Residual Stresses ◽  
Constitutive Equations ◽  
High Level Waste ◽  
Stress Model ◽  
Temperature Dependent ◽  
Steel Vessel ◽  
High Level

Residual stresses in a stainless steel vessel containing glass have been evaluated using measurements and numerical simulation. High-level nuclear wastes are often vitrified in glass cast in cylindrical stainless steel containers. Knowledge of the internal stresses generated in both the glass and container during this process is critical to structural integrity and public safety. In this research, residual stresses were measured near the surface of a High Level Waste container using an Incremental Center Hole Drilling technique. Residual stress magnitudes were found to be at or near to the yield stress in the container wall. A transient finite-element thermal-stress model has been developed to simulate temperature, distortion, and stress during casting and cooling in a simple slice domain of both the glass and the container. Contact thermal-stress elements were employed to prevent penetration at the glass–container interface. Roughness of these contact surfaces was modeled as an equivalent air gap with temperature-dependent conductivity in the thermal model. The stress model features elastic-viscoplastic constitutive equations developed based on the temperature-dependent viscosity of the glass and elastic-plastic constitutive equations for the stainless steel. The simulation was performed using the commercial ABAQUS program with a user material subroutine. The model predictions are consistent with the residual stress measurements, and the complete thermal–mechanical behavior of the system is evaluated.

Evaluation of the residual stress in stainless steel 304L hydraulically expanded joints

2020 ◽  
pp. 095440892096401
Author(s):  
Ying Hong ◽  
Xuesheng Wang ◽  
Yan Wang ◽  
Zhao Zhang ◽  
Yong Han
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Yield Strength ◽  
Residual Stresses ◽  
Heat Exchangers ◽  
Nuclear Power ◽  
The Finite Element Method ◽  
Power Stations ◽  
Stainless Steel 304 ◽  
Initial Clearance

Stainless steel 304 L tubes are commonly used in the fabrication of heat exchangers for nuclear power stations. The stress corrosion cracking (SCC) of 304 L tubes in hydraulically expanded tube-to-tubesheet joints is the main reason for the failure of heat exchangers. In this study, 304 L hydraulically expanded joint specimens were prepared and the residual stresses of a tube were evaluated with both an experimental method and the finite element method (FEM). The residual stresses in the outer and inner surfaces of the tube were measured by strain gauges. The expanding and unloading processes of the tube-to-tubesheet joints were simulated by the FEM. Furthermore, an SCC test was carried out to verify the results of the experimental measurement and the FEM. There was good agreement between the FEM and the experimental results. The distribution of the residual stress of the tube in the expanded joint was revealed by the FEM. The effects of the expansion pressure, initial tube-to-hole clearance, and yield strength of the tube on the residual stress in the transition zone that lay between the expanded and unexpanded region of the tube were investigated. The results showed that the residual stress of the expanded joint reached the maximum value when the initial clearance was eliminated. The residual stress level decreased with the decrease of the initial tube-to-hole clearance and yield strength. Finally, an effective method that would reduce the residual stress without losing tightness was proposed.

scholarly journals An Elastoplastic Thermal-Stress Analysis of a Free Plate

1956 ◽  
Vol 23 (3) ◽  
pp. 395-402
Author(s):  
Jerome Weiner
Keyword(s):  
Thermal Stress ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Uniqueness Theorem ◽  
Unique Solution ◽  
Heat Input ◽  
Thermal Stresses ◽  
Elastoplastic Material ◽  
Heuristic Solution ◽  
Peak Magnitude

Abstract The thermal stresses in a free plate of elastoplastic material subjected to a varying heat input over one face are determined. A heuristic solution is first found by suitable modifications of the known elastic solution. It is then verified that the solution satisfies all the conditions of the appropriate uniqueness theorem and represents therefore the unique solution to the problem. Residual stresses are determined and found to depend markedly on the peak magnitude of the heat input.

Changes in Residual Stress in Worked Surface Layer of Type 304 Austenitic Stainless Steel Due to Tensile Deformation

2000 ◽  
Vol 123 (1) ◽  
pp. 130-134
Author(s):  
Makoto Hayashi ◽  
Kunio Enomoto
Keyword(s):  
Solid Solution ◽  
Residual Stress ◽  
Stainless Steel ◽  
Surface Layer ◽  
Residual Stresses ◽  
Tensile Deformation ◽  
End Mill ◽  
Heat Treated ◽  
304 Austenitic Stainless Steel ◽  
Type 304

Changes in the residual stress in a worked surface layer of type 304 austenitic stainless steel due to tensile deformation were measured by the X-ray diffraction residual stress measuring method. The compressive residual stresses introduced by end-mill, end-mill side cutter, and grinder were easily changed into tensile stresses when the plate specimens were subjected to tensile stress greater than the yield stress of the solid solution heat-treated material. The residual stresses after the tensile deformation depend on the initial residual stresses and the degree of preliminary working. The behavior of the residual stress changes can be interpreted if the surface-worked material is regarded as a composite made of solid solution heat-treated material and work-hardened material.

scholarly journals Fabrication of Micro-Punch Array by Plasma Printing for Micro-Embossing into Copper Substrates

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2640
Author(s):  
Tomomi Shiratori ◽  
Tatsuhiko Aizawa ◽  
Yasuo Saito ◽  
Kuniaki Dohda
Keyword(s):  
Stainless Steel ◽  
Closed Loop ◽  
Plasma Nitriding ◽  
Testing Machine ◽  
Three Dimensional ◽  
Copper Plate ◽  
Two Dimensional ◽  
Sand Blasting ◽  
Geometric Configurations ◽  
Micro Pattern

Copper substrates were wrought to have micro-grooves for packaging by micro-stamping with use of a AISI316 stainless steel micro-punch array. The micro-texture of this arrayed punch was first tailored and compiled into CAD data. A screen film was prepared to have the tailored micro-pattern in correspondence to the CAD data. A negative pattern to this screen was printed directly onto the AISI316 die substrate. This substrate was plasma nitrided at 673 K for 14.4 ks. The unprinted die surfaces were selectively nitrogen super-saturated to have sufficiently high corrosion toughness and hardness; other surfaces were masked by the prints. The two-dimensional micro-pattern on the screen was transformed into a three-dimensional nitrogen supersaturated micro-texture embedded in the AISI316 die. The printed surfaces were selectively sand-blasted to fabricate the micro-textured punch array for micro-embossing. A uniaxial compression testing machine was utilized to describe the micro-embossing behavior in copper substrates and to investigate how the micro-texture on the die was transcribed to the copper. The micro-punch array in this study consisted of three closed loop heads with a width of 75 µm and a height of 120 µm after plasma nitriding and sand-blasting. Since the nitrogen supersaturated heads had sufficient hardness against the blasting media, the printed parts of AISI316 die were removed. The micro-embossing process was described by comparison of the geometric configurations between the multi-punch array and the embossed copper plate.

Invsetigation about Residual Stresses of Plasma-Spraying Sm2Zr2O7/YSZ Thermal Barrier Coatings of Different Substrate Conditions

2011 ◽  
Vol 308-310 ◽  
pp. 1177-1181 ◽  
Author(s):  
Hong Song Zhang ◽  
Gang Yi Cai ◽  
Shu Sen Yang
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Plasma Spraying ◽  
Thermal Stresses ◽  
Thermal Barrier ◽  
Shear Stresses ◽  
Substrate Thickness ◽  
Optimum Thickness ◽  
Slight Effect ◽  
Axial Residual Stress

Effect of substrate conditions, including material type, thickness and radius of substrate, on residual thermal stresses of plasma spraying Sm2Zr2O7/YSZ TBCs was analyzed through finite element method in this paper. The radial and shear stresses of the coating decrease with increasing of distance from the center to edge, and they decrease abruptly at the edge of the specimen, while the axial residal stress increase abruptly at the edge of substrate. All residual stresses increase with increasing of thermal expansion coefficient of substrate. The thickness of substrate has slight effect on the radial residual stress, axial residual stress and shear stress are almost uneffected by substrate thickness. The optimum thickness of substrate is 10mm. Radius of substrate have no effect on radial stress when it is greater than 28mm.

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.

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