Modeling nanostructural surface modifications in metal cutting by an approach of thermodynamic irreversibility: Derivation and experimental validation

Buchkremer, S.; Klocke, Fritz

doi:10.1007/s00161-016-0533-y

Cited by 25 publications

(19 citation statements)

References 38 publications

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“…The analysis of microstructural modifications in metal cutting of steel, i.e., the formation of a white layer, leads to a first Process Signature Component based on process simulations [28]. For this purpose a new thermodynamic model was developed by Buchkremer and Klocke.…”

Section: Exemplary Process Signature Component For Processes With a Tmentioning

confidence: 99%

“…The Process Signature Component shows that when the thermal energy falls below a certain limit, the mechanical impact starts dominating the resulting material modifications leading to residual compressive stress. With increasing mechanical energy also more heat is generated during the process, ultimately leading to residual tensile stress in the workpiece surface layer [28,29].…”

Section: Exemplary Process Signature Component For Processes With a Tmentioning

confidence: 99%

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Underlying Mechanisms for Developing Process Signatures in Manufacturing

et al. 2018

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The concept of Process Signatures allows the reliable and knowledge-based prediction of material modifications (e.g., changes of hardness, residual stress, microstructure and chemical composition) researchers in the field of surface integrity, and manufacturing technologies have already been seeking for a long time. A Process Signature is based on the correlation between the internal material loads in manufacturing processes (e.g., stress, strain, temperature) and the resulting material modifications. The target of this paper is to get a comprehensive view on the development of single Process Signature Components for processes with different predominant impacts. Particularly, a mechanism-based approach leading to significant descriptives of internal material loads for a specific material modification is proposed. By this, a deeper understanding of the underlying mechanisms leading to changes of the workpiece surface layer properties caused by manufacturing processes is provided. The challenging identification of significant mechanisms and descriptives of internal material loads is highlighted for each process, and supporting measurement methods and modeling approaches are presented. Process Signatures are expected to enable the solution of the so-called inverse problem in manufacturing.

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Section: Exemplary Process Signature Component For Processes With a Tmentioning

confidence: 99%

Section: Exemplary Process Signature Component For Processes With a Tmentioning

confidence: 99%

Underlying Mechanisms for Developing Process Signatures in Manufacturing

et al. 2018

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“…Recently, Buchkremer and Klocke have presented a thermodynamically motivated DRX model based on the variation of Helmholtz free energy to predict the dynamically recrystallized grain size during the orthogonal cutting of AISI 4140 with SFTC Deform ® -2D [21]. Their experimental and simulative results showed that the austenitizing temperature is not reached or exceeded for cutting speeds v c = 50-150 m/min and undeformed chip thicknesses h = 0.05-0.2 mm.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the research conducted by Buchkremer and Klocke, dynamic recrystallization is considered as a fundamental mechanism of the White Layer formation [21]. The above-mentioned empirical DRX models, Yada, Zener-Hollomon and JMAK, were very similar in terms of strain-based formulation of the DRX onset criteria (i.e., current plastic strain ≥ critical plastic strain) and recrystallized grain size calculation.…”

Section: Introductionmentioning

confidence: 99%

Modelling of Grain Size Evolution with Different Approaches via FEM When Hard Machining of AISI 4140

Tekkaya

Meurer

Münstermann

2020

Metals

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Thermo-mechanical loads during hard turning lead to the formation of so-called White Layers on the machined surface. Characterized by a very fine microstructure and high hardness, White Layers have a negative effect on the fatigue life of a component. The fundamental mechanism for the White Layer formation is the dynamic recrystallization (DRX). Therefore, in the current work, two different DRX models, Helmholtz free energy and Zener-Hollomon, are implemented into Abaqus/Explicit to predict the thickness of the White Layer when hard turning quenched/tempered AISI 4140 and the results are compared with each other. For the simulation of the machining process a Finite Element Method (FEM) model based on the Coupled-Eulerian-Lagrangian (CEL) method is built up. Although both DRX models achieved a very good match between predicted and measured White Layer thickness and grain size evolution on the workpiece rim zone, the Zener-Hollomon model produced more closer agreement.

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“…However, recent studies have shown that the machining process itself can be categorized as a SPD process as well [2]. Under specific conditions machining can be used to induce a nanocrystalline surface layer [3]. Therefore, the cutting process with involved and influencing cutting parameters, tool geometries and cooling conditions has to be adjusted to achieve the most desirable properties.…”

Section: Introductionmentioning

confidence: 99%

Analysis of surface integrity in machining of AISI 304 stainless steel under various cooling and cutting conditions

Klocke¹,

Döbbeler²,

Lung³

et al. 2018

AIP Conference Proceedings

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Recent studies have shown that machining under specific cooling and cutting conditions can be used to induce a nanocrystalline surface layer in the workspiece. This layer has beneficial properties, such as improved fatigue strength, wear resistance and tribological behavior. In machining, a promising approach for achieving grain refinement in the surface layer is the application of cryogenic cooling. The aim is to use the last step of the machining operation to induce the desired surface quality to save time-consuming and expensive post machining surface treatments. The material used in this study was AISI 304 stainless steel. This austenitic steel suffers from low yield strength that limits its technological applications. In this paper, liquid nitrogen (LN2) as cryogenic coolant, as well as minimum quantity lubrication (MQL), was applied and investigated. As a reference, conventional flood cooling was examined. Besides the cooling conditions, the feed rate was varied in four steps. A large rounded cutting edge radius and finishing cutting parameters were chosen to increase the mechanical load on the machined surface. The surface integrity was evaluated at both, the microstructural and the topographical levels. After turning experiments, a detailed analysis of the microstructure was carried out including the imaging of the surface layer and hardness measurements at varying depths within the machined layer. Along with microstructural investigations, different topological aspects, e.g., the surface roughness, were analyzed. It was shown that the resulting microstructure strongly depends on the cooling condition. This study also shows that it was possible to increase the micro hardness in the top surface layer significantly.

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Modeling nanostructural surface modifications in metal cutting by an approach of thermodynamic irreversibility: Derivation and experimental validation

Cited by 25 publications

References 38 publications

Underlying Mechanisms for Developing Process Signatures in Manufacturing

Underlying Mechanisms for Developing Process Signatures in Manufacturing

Modelling of Grain Size Evolution with Different Approaches via FEM When Hard Machining of AISI 4140

Analysis of surface integrity in machining of AISI 304 stainless steel under various cooling and cutting conditions

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