Cyclic Deformation Behavior of Austenitic Steels in the Temperature Range -60°C ≤T ≤550°C

Smaga, Marek; Hahnenberger, Frank; Sorich, Andreas; Eifler, Dietmar

doi:10.4028/www.scientific.net/kem.465.439

Cited by 8 publications

(4 citation statements)

References 6 publications

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“…Because, the fcc austenite has a lower strength compared to the bcc α'-martensite [11], it can be defined as the matrix and the α'-martensite as reinforcements of a "dynamically composite material" with a changing volume fraction and distribution of α'-martensite during mechanical monotonic and cyclic loading. Because α'-martensite formation leads to cyclic hardening, and this formation consequently influences significantly the fatigue life of metastable austenitic steels [11][12][13][14][15][16][17][18][19][20][21][22], it is important to have a reliable method for determining susceptibility to deformation induced α'-martensite formation. The susceptibility depends generally on two parameters: (i) the metastability of the initial austenitic microstructure, as a function of its chemical composition [4][5][6][7] and grain size [23], and (ii) the loading conditions such as load temperature [16,[19][20] and deformation rate [22].…”

Section: Introductionmentioning

confidence: 99%

Metastability and fatigue behavior of austenitic stainless steels

et al. 2018

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This study presents the results of a detailed investigation of metastability and susceptibility to deformation induced α'-martensite formation of several austenitic steels (AISI 304, AISI 321, AISI 348 and two batches from AISI 347) in the solution-annealed state. Besides conventional characterization of metastability by calculating stacking-fault energy and threshold temperature (designated as M S and M d30 ), the present work introduced a new method for determining susceptibility to α'-martensite formation. The method was based on dynamically applied local plastic deformation and non-destructive micro-magnetic measurement of α'-martensite content. The parameter I ξ was established, which correlated very well with the grade of α'-martensite formation during cyclic loading. The cyclic deformation and phase transformation behavior of cyclically loaded specimens from different metastable austenitic steels were investigated in total-strain and stress controlled fatigue tests with load ratio R = -1 at ambient temperature. The influence of the strain rate on the cyclic deformation and phase transformation behavior was also examined. During the fatigue tests, besides stress-strain hysteresis and temperature measurement, in situ micro-magnetic measurements were performed. Using the compressive measured data, the influence of plastic induced self-heating of the specimen and the strain rate on α'-martensite formation was analyzed.

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Section: Introductionmentioning

confidence: 99%

Metastability and fatigue behavior of austenitic stainless steels

et al. 2018

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“…This is caused by deformation‐induced transformation from paramagnetic austenite to ferromagnetic α’‐martensite, resulting in cyclic hardening after initial cyclic softening in the fatigue tests, which can only be seen in the cyclic deformation curves of CC specimens, Figure 10c–e. This deformation‐induced α’‐martensite formation increases the fatigue lifetime at stress‐controlled fatigue tests [19, 20, 41]. Furthermore, an increasing amount of phase transformation with decreasing stress amplitude can be observed, Figure 8.…”

Section: Resultsmentioning

confidence: 85%

Influence of microstructural defects and the surface topography on the fatigue behavior of “additively‐subtractively” manufactured specimens made of AISI 316L

Blinn

Greco

Smaga

et al. 2021

Materialwissenschaft Werkst

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As additive manufacturing offers only low surface quality, a subsequent machining of functional and highly loaded areas is required. Thus, a sound knowledge of the interrelation between the additive and subtractive manufacturing process as well as the resulting mechanical properties is indispensable. In this work, specimens were manufactured by using laser‐based powder bed fusion (L‐PBF) with substantially different sets of process parameters as well as subsequent grinding (G) or milling (M). Despite the substantially different surface topographies, the fatigue tests revealed only a slight influence of the subtractive manufacturing on the fatigue behavior, whereas the different laser‐based powder bed fusion process parameters led to pronounced changes in fatigue strength. In contrast, a significant influence of subtractive finishing on the fatigue properties of the defect‐free continuously cast (CC) reference specimens was observed. This can be explained by a dominating influence of process‐induced defects in laser‐based powder bed fusion material, which overruled the influence of surface machining. However, although both laser‐based powder bed fusion parameter sets resulted in substantial defects, one set yielded similar fatigue strength compared to continuously cast specimens.

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“…deformation-induced a 0 -martensite formation in the workpiece surface layer [42]. These beneficial alternations, therefore, result in an increased microhardness [41], higher fatigue strength in High Cycle Fatigue (HCF) regime [43] and in Very High Cycle Fatigue (VHCF) regime [44], as well as an increase in wear resistance [45]. When cryogenically turning different batches, which naturally exhibit varying austenite stability, different contents of a 0 -martensite occur despite very similar thermomechanical loads [46].…”

Section: Introductionmentioning

confidence: 99%

Surface layer hardening of metastable austenitic steel – Comparison of shot peening and cryogenic turning

Hotz

Kirsch

Zhu

et al. 2020

Journal of Materials Research and Technology

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In this paper, the effect of shot peening and cryogenic turning on the surface morphology of the metastable austenitic stainless steel AISI 347 was investigated. In the shot peening process, the coverage and the Almen intensity, which is related to the kinetic energy of the beads, were varied. During cryogenic turning, the feed rate and the cutting edge radius were varied. The manufactured workpieces were characterized by X-ray diffraction regarding the phase fractions, the residual stresses and the full width at half maximum.The microhardness in the hardened surface layer was measured to compare the hardening effect of the processes. Furthermore, the surface topography was also characterized. The novelty of the research is the direct comparison of the two methods with identical workpieces (same batch) and identical analytics. It was found that shot peening generally leads to a more pronounced surface layer hardening, while cryogenic turning allows the hardening to be realized in a shorter process chain and also leads to a better surface topography. For both hardening processes it was demonstrated how the surface morphology can be modified by adjusting the process parameter.

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Cyclic Deformation Behavior of Austenitic Steels in the Temperature Range -60°C ≤T ≤550°C

Cited by 8 publications

References 6 publications

Metastability and fatigue behavior of austenitic stainless steels

Metastability and fatigue behavior of austenitic stainless steels

Influence of microstructural defects and the surface topography on the fatigue behavior of “additively‐subtractively” manufactured specimens made of AISI 316L

Surface layer hardening of metastable austenitic steel – Comparison of shot peening and cryogenic turning

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