Deformation induced hardening when cryogenic turning,

Mayer, Patrick; Kirsch, Benjamin; Müller, Christopher; Hotz, Hendrik; Müller, Ralf; Becker, Simone; Harbou, Erik von; Skorupski, Robert; Boemke, Annika; Smaga, Marek; Eifler, Dietmar; Beck, Tilmann; Aurich, Jan C.

doi:10.1016/j.cirpj.2018.10.003

Cited by 23 publications

(19 citation statements)

References 27 publications

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“…The images captured with an optical microscope were converted into a binary image. An image processing method [50] utilizing a dilation algorithm [59] and Canny edge detection [60] was used to determine the a 0martensite distribution inside the workpiece surface layer.…”

Section: Methodsmentioning

confidence: 99%

“…As for the other hardening processes, the cryogenic turning process must be designed in such a way that the lowest possible temperatures and the highest possible mechanical loads are present in the workpiece surface layer. In the turning process, the low temperatures are achieved by means of a cryogenic cooling system and low cutting speeds [49,50]. High passive forces lead to pronounced deformations of the surface layer.…”

Section: Introductionmentioning

confidence: 99%

“…High passive forces lead to pronounced deformations of the surface layer. High feed rates and tools with a chamfered or strongly rounded cutting edge can be used to ensure high passive forces [50,51].…”

Section: Introductionmentioning

confidence: 99%

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Combination of cold drawing and cryogenic turning for modifying surface morphology of metastable austenitic AISI 347 steel

Hotz

Kirsch

Becker

et al. 2019

J. Iron Steel Res. Int.

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The application of components often depends to a large extent on the properties of the surface layer. A novel process chain for the production of components with a hardened surface layer from metastable austenitic steel was presented. The investigated metastable austenitic AISI 347 steel was cold-drawn in solution annealed condition at cryogenic temperatures for pre-hardening, followed by post-hardening via cryogenic turning. The increase in hardness in both processes was due to strain hardening and deformation-induced phase transformation from c-austenite to a 0-martensite. Cryogenic turning experiments were carried out with solution annealed AISI 347 steel as well as with solution annealed and subsequently cold-drawn AISI 347 steel. The thermomechanical load of the workpiece surface layer during the turning process as well as the resulting surface morphology was characterized. The forces and temperatures were higher in turning the cold-drawn AISI 347 steel than turning the solution annealed AISI 347 steel. After cryogenic turning of the solution annealed material, deformation-induced phase transformation and a significant increase in hardness were detected in the near-surface layer. In contrast, no additional phase transformation was observed after cryogenic turning of the cold-drawn AISI 347 steel. The maximum hardness in the surface layer was similar, whereas the hardness in the core of the cold-drawn AISI 347 steel was higher compared to that in the solution annealed AISI 347 steel.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Combination of cold drawing and cryogenic turning for modifying surface morphology of metastable austenitic AISI 347 steel

Hotz

Kirsch

Becker

et al. 2019

J. Iron Steel Res. Int.

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“…For calibration, cross sections of the cryogenically turned workpieces were treated with Beraha II etching agent in order contrast the α′-martensite needles. In addition to workpieces that were cryogenically turned within the framework of this study, workpieces with exceptionally high and low α′-martensite content from earlier studies by Mayer et al (2018) and Hotz et al (2018) were also used for calibration. After capturing images with an optical microscope, an image processing method according to Mayer et al (2018) was used in order to quantify the α′-martensite content in the surface layer and give insights into the α′-martensite distribution.…”

Section: Measurement Technologymentioning

confidence: 99%

“…The understanding and quantification of the causal correlations between the input parameters, the thermomechanical load and the surface integrity, especially regarding the α′-martensite content, is of high technological and economic importance in order to tailor the cryogenic turning process depending on specific application requirements. The effects of the input parameters on the thermomechanical load and the resulting surface integrity are partly well understood: Mayer et al (2018) reported on the influence of the cutting parameters, while the research of Hotz and Kirsch (2020) addressed the impact of the tool properties on the thermomechanical load and the surface integrity. These investigations demonstrate that, due to the deformation-induced phase transformation and strain hardening, the microhardness of the workpiece subsurface can almost be doubled by cryogenic turning.…”

Section: Introductionmentioning

confidence: 99%

Impact of the thermomechanical load on subsurface phase transformations during cryogenic turning of metastable austenitic steels

2020

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When machining metastable austenitic stainless steel with cryogenic cooling, a deformation-induced phase transformation from γ-austenite to α′-martensite can be realized in the workpiece subsurface. This leads to a higher microhardness and thus improved fatigue and wear resistance. A parametric and a non-parametric model were developed in order to investigate the correlation between the thermomechanical load in the workpiece subsurface and the resulting α′-martensite content. It was demonstrated that increasing passive forces and cutting forces promoted the deformation-induced phase transformation, while increasing temperatures had an inhibiting effect. The feed force had no significant influence on the α′-martensite content. With the proposed models it is now possible to estimate the α′-martensite content during cryogenic turning by means of in-situ measurement of process forces and temperatures.

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Eddy Current Detection of the Martensitic Transformation in AISI304 Induced upon Cryogenic Cutting

Fricke

Nguyen

Breidenstein

et al. 2020

steel research int.

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The combination of a hard subsurface layer and a ductile component core is advantageous for many applications. Steels are often heat treated to create such a hardened subsurface, which is both time‐ and energy‐consuming. It is of great advantage to create a hardened subsurface directly within the machining process, as the production line of most components includes such a process to produce the desired geometric dimensions and surface quality. To achieve a martensitic subsurface layer within the machining process, cryogenic, external turning using a metastable AISI304 austenitic steel is used herein. Herein eddy current testing and the analysis of higher harmonics are used for the detection of the ferromagnetic, martensitic phase in the parent austenite. A good correlation is found between the martensite content and the amplitude of the signals measured. Therefore, eddy current testing is considered as a suitable real‐time, nondestructive testing method, which forms the basis for the generation of a tailored, deformation‐induced martensitic subsurface layer during external turning.

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Deformation induced hardening when cryogenic turning,

Cited by 23 publications

References 27 publications

Combination of cold drawing and cryogenic turning for modifying surface morphology of metastable austenitic AISI 347 steel

Combination of cold drawing and cryogenic turning for modifying surface morphology of metastable austenitic AISI 347 steel

Impact of the thermomechanical load on subsurface phase transformations during cryogenic turning of metastable austenitic steels

Eddy Current Detection of the Martensitic Transformation in AISI304 Induced upon Cryogenic Cutting

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