Investigation of clamping effect on the welding residual stress and deformation of monel plates by using the ultrasonic stress measurement and finite element method

Welding of nickel-based alloys is increasingly used in the industry to manufacture many important components of the marine industries, chemical processing, etc. In this study, a 3D thermomechanical finite element (FE) analysis is employed to evaluate residual stresses and deformations caused by the tungsten inert gas (TIG) welding of Monel 400 (Nickel-Copper alloy) plates. The FE results related to the residual stresses and deformations have been verified by using the hole-drilling stress measurement and common dimensional measurement tools, respectively. Residual stresses analyzed by the FE simulation are then compared with those obtained from ultrasonic stress measurement. The ultrasonic stress measurement is based on acoustoelasticity law, which presents the relation between the acoustic waves and the stress of material. The ultrasonic stress measurement is carried out by using longitudinal critically refracted (LCR) waves which are longitudinal ultrasonic waves propagated parallel to the surface inside the tested material. Two welded plates are experimentally prepared (with and without using clamp) to investigate the clamping effect on the welding residual stress and deformations. By utilizing the FE analysis along with the LCR method, the distribution of longitudinal residual stress could be achieved. It has been concluded that the applied methodologies are enough accurate to distinguish the clamping effect on the welding residual stresses and deformations of Monel plates

Evaluation of sub-surface residual stress by ultrasonic method and finite-element analysis of welding process in a Monel pressure vessel

Welding of nickel-based alloys is increasingly used in the industry to manufacture various important structures in the marine industries, chemical processing, etc. This study investigates evaluation of sub-surface residual stresses, which are produced by the welding process in a pressure vessel made from Monel 400 alloy. The residual stresses are experimentally measured by ultrasonic method in which longitudinal critically refracted (LCR) waves are propagated inside the specimen to evaluate the effect of stress on the wave velocity. Any difference in the wave velocity could be transformed to the material stress by using acoustoelasticity relations. A nondestructive hydro-test process is used to measure the acoustoelastic constant, which is an important material property needed to be embedded in the acoustoelasticity relations. By using a different frequency range than the ultrasonic transducers, the LCR wave penetrates in different depths of the specimen to measure the sub-surface stresses. The welding processes are also numerically analyzed by a 3D thermo-mechanical finite-element (FE) model, which is validated by hole-drilling stressmeasurement method. The residual stresses calculated by FE simulation are then compared with those obtained from the ultrasonic stress measurement and an acceptable agreement is achieved. It is demonstrated that the sub-surface residual stresses of the Monel pressure vessel could be accurately evaluated by combination of the FE simulation and stress measurement implemented by the LCR waves

Comparison between contact and immersion ultrasonic method to evaluate welding residual stresses of dissimilar joints

This paper presents a comparison of contact and immersion waves used to measure residual stresses. The residual stresses are produced due to a dissimilar welding of stainless steel (304) to carbon steel (A106). Longitudinal critically refracted (LCR) wave propagated by 2. MHz contact and immersion ultrasonic transducers is employed to measure the residual stresses. A Finite Element (FE) model of welding process, which is validated by hole-drilling method, is used to verify the ultrasonic results while an acceptable agreement is achieved. The best agreement is observed in the parent material while the maximum difference is measured in the heat affected zone (HAZ). The results show no considerable difference between using contact and immersion transducers in ultrasonic stress measurement of dissimilar joints

Comparison between contact and immersion method in ultrasonic stress measurement of welded stainless steel plates

This study presents a comparison between contact and immersion ultrasonic method to measure welding residual stress of austen-itic stainless steel plates (AISI 304L). Longitudinal critically refracted (LCR) waves are employed to measure the residual stresses. By using contact and immersion transducers, a 3D distribution of longitudinal residual stress for the entire of the welded plate is presented. A finite-element model of welding process, which is validated by the hole-drilling method, is used to verify the ultrasonic results. The results show no considerable differences between using contact or immersion transducers in ultrasonic stress measurement of stainless steel plates; however, some practical considerations are mentioned

Using finite element and ultrasonic method to evaluate welding longitudinal residual stress through the thickness in austenitic stainless steel plates

This paper uses a 3D thermo-mechanical finite element analysis to evaluate welding residual stresses in austenitic stainless steel plates of AISI 304L. The finite element model has been verified by the hole drilling method. The validated finite element (FE) model is then compared with the ultrasonic stress measurement based on acoustoelasticity. This technique uses longitudinal critically refracted (LCR) waves that travel parallel to the surface within an effective depth. The residual stresses through the thickness of plates are evaluated by four different series (1. MHz, 2. MHz, 4. MHz and 5. MHz) of transducers. By combining FE and LCR method (known as FELCR method) a 3D distribution of residual stress for the entire of the welded plate is presented. To find the acoustoelastic constant of the heat affected zone (HAZ), a metallographic investigation is done to reproduce HAZ microstructure in a tensile test sample. It has been shown that the residual stresses through the thickness of stainless steel plates can be evaluated by FELCR method

Evaluation of hoop residual stress variations in the thickness of dissimilar welded pipes by using the LCR ultrasonic waves

Mjerenje naprezanja pomoću ultrazvučnih valova temelji se na akustičnoelastičnom zakonu, t.j.odnosu između naprezanja i brzine valova u inženjerskim materijalima. Uzdužni kritički lomljen - Longitudinal critically refracted (LCR) val je popularni ultrazvučni val u primjeni ultrazvučnog mjerenja naprezanja. LCR val je masovni uzdužni val koji putuje na efektivnoj dubini ispod površine. U ovom radu procjenjuje se varijacija cirkularnog zaostalog naprezanja u debljini cijevi. Cijev je proizvedena zavarivanjem dviju različitih cijevi od nehrđajućeg čelika AISI 304 i ugljičnog čelika tipa A106-B. Varijacije zaostalih naprezanja u debljini cijevi mjere se pomoću četiri različite frekvencije pretvarača, dok su nominalne frekvencije 1 MHz, 2 MHz, 4 MHz i 5 MHz. Uporabom različitih frekvencija omogućeno je LCR valovima da prodru do različitih dubina i mjere veličinu naprezanja cijevi. Pokazalo se da se razlika u naprezanju između unutarnje i vanjske površine cijevi i također između strane cijevi od nehrđajućeg čelika i one od ugljičnog čelika može procijeniti pomoću LCR valova.Stress measurement by using ultrasonic waves is based on acoustoelasticity law, i. e. the relation between stress and wave velocity in engineering materials. Longitudinal critically refracted (LCR) wave is a popular ultrasonic wave in the ultrasonic stress measurement application. The LCR wave is a bulk longitudinal wave that travels within an effective depth underneath the surface. This paper evaluates hoop residual stress variation in the thickness of a pipe. The pipe is manufactured by welding two dissimilar pipes from AISI stainless steel 304 and carbon steel A106-B type. The residual stresses variations in the thickness of pipe are measured by using four different frequencies of transducers while the nominal frequencies are 1 MHz, 2 MHz, 4 MHz and 5 MHz. Using different frequencies enables the LCR waves to penetrate in different depths and measure the bulk stresses of pipe. It has been shown that the stress difference between inner and outer surfaces of pipes and also between the stainless steel and carbon steel side of dissimilar pipe can be evaluated by using the LCR waves

Taguchi optimization and ultrasonic measurement of residual stresses in the friction stir welding

The main goal of this study is optimization of residual stresses produced by friction stir welding (FSW) of 5086 aluminum plates. Taguchi method is employed as statistical design of experiment (DOE) to optimize welding parameters including feed rate, rotational speed, pin diameter and shoulder diameter. The optimization process depends on effect of the welding parameters on longitudinal residual stress, which is measured by employing ultrasonic technique. The ultrasonic measurement method is based on acoustoelasticity law, which describes the relation between acoustic waves and internal stresses of the material. In this study, the ultrasonic stress measurement is fulfilled by using longitudinal critically refracted (LCR) waves which are longitudinal ultrasonic waves propagated parallel to the surface within an effective depth. The ultrasonic stress measurement results are also verified by employing the hole-drilling standard technique. By using statistical analysis of variance (ANOVA), it has been concluded that the most significant effect on the longitudinal residual stress peak is related to the feed rate while the pin and shoulder diameter have no dominant effect. The rotational speed variation leads to changing the welding heat input which affects on the residual stress considerably

Nondestructive evaluation of welding residual stresses in austenitic stainless steel plates

This article investigates the nondestructive capability of ultrasonic waves in residual stress evaluation of austenitic stainless steel plates (AISI 304L). Longitudinal critically refracted (LCR) waves are employed to measure the residual stresses. Measuring the acoustoelastic constant through the tensile test is eliminated on the main investigated sample to keep it intact. Another welded plate with the same welding specification, geometry, thickness, and the same material is used to extract tensile test samples. To find the acoustoelastic constant of the heat affected zone (HAZ), a metallographic investigation is done to produce microstructure similar to that of the HAZ in a tensile test sample. A finite element model of welding process, which is validated by hole-drilling method, is used to verify the ultrasonic results. The results show good agreement between finite element and ultrasonic stress measurements which is accomplished nondestructively

Residual stress evaluation in dissimilar welded joints using finite element simulation and the L CR ultrasonic wave

Subsurface stresses in welded structures increase the likelihood of fatigue cracks and environmental induced material degradation. The ability to evaluate stresses at the surface as well as in the interior of welded structural members would substantially increase the accuracy of structure life estimation. The longitudinal critically refracted (L CR) wave is a bulk longitudinal mode that travels within an effective depth underneath the surface. It may be used to detect in-plane subsurface stresses in the structures. This paper presents a three dimensional thermo-mechanical analysis to evaluate welding residual stresses in dissimilar plate-plate joint of AISI stainless steel 304 and Carbon Steel A106-B type. After finite element simulation, the residual stresses were evaluated by L CR ultrasonic waves. Finally the results of two methods were compared and verified by hole-drilling method. This paper introduces a combination of "Finite Element Welding Simulation" and "Ultrasonic Stress Measurement using the L CR Wave" which is called as "FEL CR". The capabilities of FEL CR″. The capabilities of FEL CR in residual stress measurement are confirmed here. And also this paper evaluates residual stresses of dissimilar welded joints by LCR ultrasonic waves. It has been shown that predicted residual stress from three dimensional FE analyses is in reasonable agreement with measured residual stress from LCR method and also the results of both are verified with hole-drilling experimental measurements

Robotic non-destructive testing

Non-destructive testing (NDT) and evaluation (NDE) are commonly referred to as the vast group of analysis techniques used in civil, medical, and industrial sectors to evaluate the properties of materials, tissues, components, or structures without causing any damage [...]