An analysis of thermal autofrettage process with heat treatment

Shufen, Rajkumar; Dixit, Uday S.

doi:10.1016/j.ijmecsci.2018.05.053

Cited by 19 publications

(6 citation statements)

References 16 publications

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“…The geometrical parameters of the mandrel evaluated in this study, inlet angle and the straight zone length, showed no significant influence in the residual stresses after the cold expansion process. This behaviour did not match the results showed by the numerical analysis performed by Gibson et al [5,6] where there was significant variation of the hoop stress of thick-walled cylinders when the geometrical parameters of the swage were modified. Figure 25 shows the residual hoop stress obtained from the analysis performed by Gibson [5], where the influence of the straight zone length was analysed.…”

Section: Discussioncontrasting

confidence: 71%

“…Development of new steel alloys during the first half of the 20th century with higher yield and ultimate tensile strengths generated an increment of the necessary autofrettage pressure to reach the requirements of residual stresses. The inherent process difficulties to reach these pressure levels motivated the development of alternative processes (explosive autofrettage [2,3], double-layer autofrettage [4], thermal autofrettage [5], rotational autofrettage [6], etc.). In this context, around the middle of the last century, an innovative cold-forming process in gun barrels was presented [7]: the mechanical autofrettage or swaging.…”

Section: Introductionmentioning

confidence: 99%

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Parametric Analysis of the Mandrel Geometrical Data in a Cold Expansion Process of Small Holes Drilled in Thick Plates

et al. 2019

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Cold expansion technology is a cold-forming process widely used in aeronautics to extend the fatigue life of riveted and bolted holes. During this process, an oversized mandrel is pushed through the hole in order to yield it and generate compressive residual stresses contributing to the fatigue life extension of the hole. In this paper, a parametric analysis of the mandrel geometrical data (inlet angle straight zone length and diametric interference) and their influence on the residual stresses was carried out using a finite element method (FEM). The obtained results were compared with the conclusions presented in a previous parametric FEM analysis on the influence of the swage geometry in a swaging cold-forming process of gun barrels. This process could be considered, in a simplified way, as a scale-up of the cold expansion process of small holes, and this investigation demonstrated the influence of the diameter ratio (K) on the relation between the mandrel or swage geometry and the residual stresses obtained after the cold-forming process.

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Section: Discussioncontrasting

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Parametric Analysis of the Mandrel Geometrical Data in a Cold Expansion Process of Small Holes Drilled in Thick Plates

et al. 2019

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“…Jahromi et al [27] claimed that the autofrettage of a metal tube with reinforced ceramic particles on its inner surface increases the amount of compressive residual stress. Shufen et al [28] proposed that locally heating a 1080-steel tube to an elevated temperature using thermal autofrettage followed by its cooling induces compressive stresses at its inner surface. They reported that the development of the compressive residual stresses during cooling increases the fatigue performance of the tube.…”

Section: Reinforcement Of Toolingsmentioning

confidence: 99%

Reinforcement of Tooling Using Residual Stresses Generated by Cladding by Arc Welding

Israr

Buhl

Härtel

et al. 2022

Metals

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Cladding is typically used to protect components from wear and corrosion while also improving the aesthetic value and reliability of the substrate. The cladding process induces significant residual stresses due to the temperature difference between the substrate and the clad layer. However, these residual stresses could be effectively utilized by modifying processes and geometrical parameters. This paper introduces a novel methodology for using the weld-cladding process as a cost-effective alternative to various existing reinforcement techniques. The numerical analyses are performed to maximize the reinforcement of a cylindrical tool. The investigation of how the weld cladding develops compressive stresses on the specimen in response to a change in the weld beads and the welding sequence is presented. For the benchmark shape, experimental verification of the numerical model is performed. The influence of the distance between the weld beads and the effect of the tool diameter is numerically investigated. Furthermore, the variation in compressive stresses due to temperature fluctuations during the extrusion process has been evaluated. The results showed that adequate compressive stresses are generated on the welded parts through the cladding process after cooling. More compressive stresses are induced in the tool as the cross-section of the weld bead is increased. Furthermore, keeping a gap between the adjacent beads improves tool reinforcement. Hence, the targeted reinforcement of the substrate can be achieved by optimizing the welding sequence and process parameters.

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“…The resulting equation can be solved numerically to find ϕ c as a function of ϕ a . Using this solution, ρ c as a function of ϕ a is immediate from Equation 25, and then C 1 is a function of ϕ a from any part of Equations (27). Equation 23allows for all these quantities to be expressed as a function of p 0 .…”

Section: Elastic/plastic Stress Solutionmentioning

confidence: 99%

“…In addition to the autofrettage treatment by internal pressure, thermal and rotational autofrettage treatments are widely used. Thermal autofrettage has been studied in [24][25][26][27], and rotational autofrettage in [28,29].…”

Section: Introductionmentioning

confidence: 99%

A Theory of Autofrettage for Open-Ended, Polar Orthotropic Cylinders

2019

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Autofrettage is a widely used process to enhance the fatigue life of holes. In the theoretical investigation presented in this article, a semi-analytic solution is derived for a polar, orthotropic, open-ended cylinder subjected to internal pressure, followed by unloading. Numerical techniques are only necessary to solve a linear differential equation and evaluate ordinary integrals. The generalized Hooke’s law connects the elastic portion of strain and stress. The flow theory of plasticity is employed. Plastic yielding is controlled by the Tsai–Hill yield criterion and its associated flow rule. It is shown that using the strain rate compatibility equation facilitates the solution. The general solution takes into account that elastic and plastic properties can be anisotropic. An illustrative example demonstrates the effect of plastic anisotropy on the distribution of stresses and strains, including residual stresses and strain, for elastically isotropic materials.

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An analysis of thermal autofrettage process with heat treatment

Cited by 19 publications

References 16 publications

Parametric Analysis of the Mandrel Geometrical Data in a Cold Expansion Process of Small Holes Drilled in Thick Plates

Parametric Analysis of the Mandrel Geometrical Data in a Cold Expansion Process of Small Holes Drilled in Thick Plates

Reinforcement of Tooling Using Residual Stresses Generated by Cladding by Arc Welding

A Theory of Autofrettage for Open-Ended, Polar Orthotropic Cylinders

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