Evaluation of Fracture Initiation in the Mannesmann Piercing Process

Fanini, Silvio; Ghiotti, Andrea; Bruschi, Stefania

doi:10.1063/1.2729596

Cited by 6 publications

(5 citation statements)

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“…Ceretti et al modelled crack opening using a Latham and Cockroft ductile damage model [4,5]. In the following years, Fanini and coworkers produced an in-depth study of the Mannesmann effect [6][7][8][9][10], explained it by the occurrence of a tensile stress in the direction normal to the compression by the rolls in the cross section. They focused on the onset of crack opening mechanism and therefore omitted the piercer plug in their simulations for simplicity.…”

Section: Rotation Axismentioning

confidence: 99%

“…They focused on the onset of crack opening mechanism and therefore omitted the piercer plug in their simulations for simplicity. Comparing several ductile damage models, they finally advocated a version of the Lemaitre model [8] and emphasized the impact of pre-existing porosity due to casting [6,9] or more generally of any metallurgical weakness or brittleness of the centreline of the billet. Starting from this conclusion, Skripalenko and coworkers recently studied the effect of the plug shape and more generally of the tooling on final shell porosity [11][12]; among the damage models, they promoted the normalized Latham and Cockroft one [13].…”

Section: Rotation Axismentioning

confidence: 99%

“…Comparing several ductile damage models, they finally advocated a version of the Lemaitre model [8]. They emphasized the impact of pre-existing porosity due to casting [6,9] or more generally of any metallurgical weakness or brittleness of the centerline of the billet. Starting from this conclusion, Skripalenko and coworkers recently studied the effect of the plug shape and more generally of the tooling on final shell porosity [11][12].…”

Section: Defect and Diffusion Forummentioning

confidence: 99%

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Identifying Heterogeneous Friction Coefficients on the Hot Forming Tools in Mannesmann Cross-Roll Piercing

Fernandes

Marouf

Montmitonnet

et al. 2022

DDF

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As in all metal rolling processes, Mannesmann cross-roll piercing relies on entrainment by friction between the billet and the rolls. But contrary to other rolling processes, a strong back-push is imposed by the piercing force (Fig. 1). Entrainment of the billet through the mill is therefore a critical problem which can be solved by optimizing the surface state of all tools (rolls, guide rolls, piercing plug). This is why the effect of friction with all the tools on the tube entrainment speed and on the state of stress has been investigated using the 3D Finite Element Method (FEM, ForgeNxT). It has been found that friction between billet and cross rolls is a driving force on the first (upstream) half of the rolls but may become resistant on the downstream part for certain process settings. Friction between piercer plug and hot metal is always resistant. Friction with rotating Diescher guide disks is a driving force in the piercing direction, but works against pierced shell rotation, causing shell torsion (“twist”). If static lateral guide shoes are preferred, their pure sliding friction is resistant in both directions. Friction on the upstream part of rolls must therefore be as high as possible for correct entrainment and process stability, which explains the practice of giving it very high roughness. The surface of the piercer plug must be smoother to minimize its frictional resistance. The surface states of lateral guides and of the downstream half of rolls can be used as process optimization variables. Results suggest how to obtain estimates of friction coefficients from mill measurements.

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Section: Rotation Axismentioning

confidence: 99%

Section: Rotation Axismentioning

confidence: 99%

Section: Defect and Diffusion Forummentioning

confidence: 99%

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Identifying Heterogeneous Friction Coefficients on the Hot Forming Tools in Mannesmann Cross-Roll Piercing

Fernandes

Marouf

Montmitonnet

et al. 2022

DDF

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“…Regarding the RTP process, the Hansel–Spittel law has been frequently used for the constitutive modelling of the billet material behaviour. Ghiotti and Fanini [ 23 , 24 , 25 ] modelled the flow stress of a DIN St52 steel in a skew rolling process with this formulation. Pschera et al [ 26 ] used this constitutive formulation for modelling the 10CrMo9-10 steel rheological behaviour during the RTP and the posterior analysis of material damage.…”

Section: Introductionmentioning

confidence: 99%

Application of an Incremental Constitutive Model for the FE Analysis of Material Dynamic Restoration in the Rotary Tube Piercing Process

Murillo-Marrodán

García

Barco³

et al. 2020

Materials

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In the numerical simulation of hot forming processes, the correct description of material flow stress is very important for the accuracy of the results. For complex manufacturing processes, such as the rotary tube piercing (RTP), constitutive laws based on both power and exponential mathematical expressions are commonly used due to its inherent simplicity, despite the limitations that this approach involves, namely, the use of accumulated strain as a state parameter. In this paper, a constitutive model of the P91 steel derived from the evolution of dislocation density with strain, which takes into account the mechanisms of dynamic recovery (DRV) and dynamic recrystallization (DRX), is proposed for the finite element (FE) analysis of the RTP process. The material model is developed in an incremental manner to allow its implementation in the FE code FORGE®. The success of this implementation is confirmed by the good correlation between results of the simulation and experimental measurements of the manufactured tube (elongation, twist angle, mean wall thickness and eccentricity). In addition, this incremental model allows addressing how the restoring mechanisms of DRV and DRV occur during the RTP process. The analysis puts into evidence that DRV and DRX prevail over each other cyclically, following an alternating sequence during the material processing, due mainly to the effect of the strain rate on the material.

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“…These models are based on the slip line field theory or upper bound techniques [1] and, more recently, on FE simulations of the deformation process [2][3][4]. Predictive models, on the other hand, are founded on energy-based damage theories [5,6] and provide a more comprehensive description of the process-related causes and phenomena of the ME [7,8]. They can be particularly useful in predicting the process conditions that cause the fracture to occur and propagate.…”

Section: Introductionmentioning

confidence: 99%