Evaluation of ductile fracture in welded tubes with tensile, hardness, flaring tests

Jang, Yun-Seok; Lee, Youngseo; Song, Mingjun; Han, Do-Suck; Kim, Naksoo; Lee, Hyungyil

doi:10.1016/j.ijmecsci.2021.106745

Cited by 10 publications

(4 citation statements)

References 58 publications

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“…The relationship between microhardness and flow stress was approximately constant [41][42][43]. That is, the flow stress was in proportion to the microhardness, as shown in Equation ( 4).…”

Section: Describing the Continuous Change In Flow Stressmentioning

confidence: 97%

The Development of a Continuous Constitutive Model for Thin-Shell Components with A Sharp Change in the Property at Welded Joints

He,

Ruan,

Liang

et al. 2024

Materials

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Large-dimension complex integral thin-shell components are widely used in advanced transportation equipment. However, with the dimensional limitations of raw blanks and the manufacturing process, there are inhomogeneous geometric and mechanical properties at welded joints after welding, which have a significant effect on the subsequent forming process. Therefore, in this paper, the microstructure of welded joints with a sharp property change was accurately characterized by the proposed isothermal treatment method using the BR1500HS welded tube as an example. In addition, an accurate constitutive model of welded tubes was established to predict the deformation behavior. Firstly, the heat-treated specimens were subjected to uniaxial tensile tests and the stress–strain curves under different heat treatment conditions were obtained. Then, the continuous change in flow stress in the direction of the base metal zone, the heat-affected zone and the weld zone was described by the relationship between the microhardness, flow stress and center angle of the welded tube. Using such a method, a continuous constitutive model of welded tubes has been established. Finally, the constitutive model was compiled into finite-element software as a user material subroutine (VUHARD). The reliability of the established constitutive model was verified by simulating the free hydro-bulging process of welded tubes. The results indicated that the continuous constitutive model can well describe the deformation response during the free hydro-bulging process, and accurately predicted the equivalent strain distribution and thickness thinning rate. This study provides guidance in accurately predicting the plastic deformation behavior of welded tubes and its application in practice in hydroforming industries.

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“…The relationship between microhardness and flow stress was approximately constant [41][42][43]. That is, the flow stress was in proportion to the microhardness, as shown in Equation ( 4).…”

Section: Describing the Continuous Change In Flow Stressmentioning

confidence: 97%

The Development of a Continuous Constitutive Model for Thin-Shell Components with A Sharp Change in the Property at Welded Joints

He,

Ruan,

Liang

et al. 2024

Materials

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show abstract

“…The thickness of the tube end is not changed at the yield moment, ε t = 0. The effective strain of the tube end at the yielding moment could be obtained Equation (8).…”

Section: Derivation Of the Yield Stress Expressionmentioning

confidence: 99%

“…As one of the most simple and popular tube-endforming processes, the tube flaring process has already been widely used to evaluate the hydroformability of tubular material and manufacture the products, such as revolution vessels, connection between tubes, etc. [6][7][8][9][10]. Pushing a conical tool into a tube, which is axially immovably supported at its bottom, or pushing a tube in its axial direction on a spatially fixed conical tool to expand the end of the tubular material is understood as tube flaring [11,12].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Circumferential Mechanical Properties of Tubular Material by Flaring Test

Zhang

Manabe

et al. 2022

Metals

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The investigation into the circumferential mechanical properties of tubular materials has been receiving increasing attention, since the tube hydroforming process has been used in the tubular materials forming field, because the circumferential mechanical properties have a significant effect on the hydroformability of the tubular materials. In the present study, a method for evaluation of the circumferential mechanical properties of the tubular materials with the flaring test was proposed. The expressions for the yield stress, strain hardening coefficient and exponent values of the tube were successfully derived based on the geometrical and mechanical relationships in the tube flaring test. To verify the reliability of this method, the calculated results of the yield stress, strain hardening coefficient and exponent values, obtained from the newly proposed method, were compared to the ones obtained with the conventional tensile tests. It was found that the method proposed in the current study is reliable, with high accuracy. The method is appropriate to evaluate the circumferential mechanical properties of the tubular materials.

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“…To accurately simulate the deformation behavior of welded steel tube during hydroforming process, the welded tube was modeled as two material system, via: weld zone and base metal region, whose stress-strain curves could be derived by considering the rule of mixture, as presented by Omar et al [20]. To predict the fracture of welded tube, Jang et al [21] established the constitutive model of the weld zone by the rule of mixture and the flow stress of the weld was estimated from the hardness ratio. Additionally, Liu et al [22] analyzed the cross section deformation of thin-walled heterogeneous rectangular welded tube in rotary draw bending by considering different yield criteria.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the influence of weld position on the deformation behavior of welded tube during free bending process

Cheng

Pan

Bai

et al. 2022

Int J Adv Manuf Technol

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The non-uniform distribution of the mechanical properties of welded tube would affect the plastic deformation behavior of tube during the free bending process. To explore the influence of weld position on the forming quality and axis dimensional accuracy of welded tube, the free bending experiment and numerical simulation of welded tube were conducted in this paper. First, the principle of free bending was theoretical deduced and the stress distribution of bent tube was analyzed. Then the hardness test and uniaxial tensile test were conducted to obtain the mechanical properties of weld zone and parent zone of welded tube. The material strength in the weld zone of welded tube is significantly higher than that in the parent zone.Finally, the free bending experiment and numerical simulation with different weld position were carried out, and the influence of weld position on the bending radius, cross-sectional distortion and wall thickness of bent tube was discussed. All these findings advance the insight into the free bending deformation behavior of welded tube and help to improve the forming quality of welded tube and facilitate the application of free bending technology in welded tube.

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Evaluation of ductile fracture in welded tubes with tensile, hardness, flaring tests

Cited by 10 publications

References 58 publications

The Development of a Continuous Constitutive Model for Thin-Shell Components with A Sharp Change in the Property at Welded Joints

The Development of a Continuous Constitutive Model for Thin-Shell Components with A Sharp Change in the Property at Welded Joints

Evaluation of Circumferential Mechanical Properties of Tubular Material by Flaring Test

Investigation on the influence of weld position on the deformation behavior of welded tube during free bending process

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