Cyclic plasticity, cyclic creep and fatigue life of duplex stainless steel in cyclic loading with positive mean stress

Polák, Jaroslav; Petrenec, Martin; Man, Jiří

doi:10.4149/km_2011_5_347

Cited by 4 publications

(7 citation statements)

References 21 publications

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“…Fatigue damage evolution is nearly identical as in symmetrical strain controlled loading. When mean stress increases the cyclic creep rate increases and mean strain develops rapidly during the initial cycles and later shows a tendency to saturation 36 . Similar features exhibits our SAF 2507 steel cycled with various stress amplitudes and mean stresses.…”

Section: Resultssupporting

confidence: 79%

“…The hysteresis loops were recorded and plastic strain amplitude ɛ ap and mean strain ɛ m were evaluated neglecting the presence of the shallow notch. Plastic strain amplitude was equal to the half‐width of the closed hysteresis loop and mean strain was equal to the mean value of the maximum and minimum strain in a cycle 36 …”

Section: Methodsmentioning

confidence: 99%

“…Plastic strain amplitude was equal to the half-width of the closed hysteresis loop and mean strain was equal to the mean value of the maximum and minimum strain in a cycle. 36 Cycling was interrupted in predefined number of cycles and the central area of the notch was photographed using Navitar microscope with CCD MegaView IIIu digital camera. To document the surface evolution in the central area of the notch around 40 images were taken at each interruption of cycling.…”

Section: N I T I a T I O N A N D S H O R T C R A C K G R O W T H -Ementioning

confidence: 99%

“…Recent study of the cyclic stress–strain and cyclic creep behaviour of SAF 2205 duplex steel in stress controlled loading with positive mean stresses 36 revealed the dependence of the cyclic stress–strain curve and of the fatigue life on the mean stress. In the interval of stress amplitudes and mean stresses leading to the fatigue lives from 10 4 cycles to 10 7 cycles positive mean stress resulted in the decrease of the fatigue life.…”

Section: Introductionmentioning

confidence: 99%

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Initiation and short crack growth in austenitic–ferritic duplex steel‐effect of positive mean stress

Polák

Petrenec

Man

et al. 2011

Fatigue Fract Eng Mat Struct

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A B S T R A C TThe effect of the mean stress on the crack initiation and short crack growth of austenitic-ferritic duplex steel has been studied. High mean stresses and stress amplitudes result in appreciable mean strain relaxation and long-term hardening. Mean stress produces unidirectional slip bands and slip steps that serve as nuclei for persistent slip bands and persistent slip markings. It leads to the acceleration of the crack initiation and production of a high density of cracks. Crack linkage contributes to the growth of short cracks. The concept of equivalent crack was used to describe the crack growth. The kinetics of short crack growth with positive mean stress is similar to that in symmetric loading, that is, exponential growth is observed. Positive mean stress results in earlier crack initiation and in the acceleration of the crack growth rate. Both factors contribute to the decrease of the fatigue life. a = crack length a ir = length of real initiated crack a ie = initial equivalent crack length a f = length of a final crack σ a = stress amplitude σ m = mean stress σ 0.2 = yield stress σ UTS = ultimate tensile strength ε m = mean strain ε ap = plastic strain amplitude ε f = fatigue ductility coefficient c = fatigue ductility exponent k g = crack growth coefficient K tot = total stress intensity range K max tot = total maximum stress intensity N = number of cycles p = Walker parameter N i = number of cycles to initiation N f = number of cycles to fracture I N T R O D U C T I O NIn the prediction of fatigue life of materials and structures two main approaches have been applied. 1-5 In the first approach the fatigue life curves of smooth specimens are employed. Originally stress-based Wöhler curve and later, recognizing the importance of the plastic strain for fatigue life, Manson-Coffin curve have been used. 2,3 For Correspondence: J. Polák. E-mail: polak@ipm.cz bodies without stress and strain gradient the fatigue life curves can be used directly for life prediction. In bodies with notches the local stress-strain approach based on fatigue life curves allows to estimate the macrocrack initiation. 4,5 In the second approach the fatigue life of bodies containing macroscopic long cracks is evaluated using fracture mechanics methodology. 6,7 It allows the more exact evaluation of the fatigue life or residual fatigue life by adopting the integration of the crack growth rate.

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Section: Resultssupporting

confidence: 79%

Section: Methodsmentioning

confidence: 99%

Section: N I T I a T I O N A N D S H O R T C R A C K G R O W T H -Ementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Initiation and short crack growth in austenitic–ferritic duplex steel‐effect of positive mean stress

Polák

Petrenec

Man

et al. 2011

Fatigue Fract Eng Mat Struct

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“…Lead is insoluble in free-cutting steel and during the cutting process lead particles are sheared and smeared over the tool-chip interface. 9,10 Lead improves the machinability with little effect on mechanical properties. Due to its low shear strength, lead acts as a solid lubricant.…”

Section: Introductionmentioning

confidence: 99%

Analyzing the heat-treatment effect on the mechanical properties of free-cutting steels

Külekçi¹,

Eşme²,

Kahraman³

et al. 2016

Mater. Tehnol.

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In this research, the heat-treatment effect on the mechanical properties of free-cutting steels was investigated. Free-cutting steels (FCSs) are used where high degrees of machining are required as they increase the machining speed and reduce the tool wear. The effect of heat treatment on mechanical properties was identified using tensile and fatigue tests, and microstructure images taken with a scanning electron microscope (SEM). The studied material included commercially available AISI 12L14 cylindrical bars of free-cutting steel. FCS was heated to 900°C and held at this temperature for different time spans. The degradation of the mechanical properties of free-cutting steel due to the elevated temperature was assessed. At a microscopic level, more mechanical damage was observed between the steel matrix and the second phase of the heat-affected specimens. Keywords: fatigue, tensile strength, free-cutting steel, heat treatment V prispevku je bil raziskan vpliv toplotne obdelave na mehanske lastnosti avtomatnih jekel. Avtomatna jekla (FCS) se uporabljajo v primerih, ko so zahtevane velike stopnje obdelave, saj dopu{~ajo ve~je hitrosti rezanja ob manj{i obrabi orodja. Vpliv toplotne obdelave na mehanske lastnosti je bil dolo~en z rezultati nateznega preizkusa in preizkusa utrujenosti. Z vrsti~nim elektronskim mikroskopom (SEM) so bili narejeni posnetki mikrostrukture. Preiskovane so bile komercialno dosegljive palice iz avtomatnega jekla AISI 12L14. FCS je bil segret na 900°C in razli~no dolgo zadr`an na tej temperaturi. Dolo~eno je bilo zmanj{anje mehanskih lastnosti avtomatnega jekla zaradi povi{ane temperature. V toplotno obdelanih vzorcih je bilo z mikroskopom opa`enih ve~mehanskih po{kodb.

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Mechanical and functional fatigue of non-oriented and grain-oriented electrical steels

Backes,

Smaga,

Beck

2024

International Journal of Fatigue

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Cyclic plasticity, cyclic creep and fatigue life of duplex stainless steel in cyclic loading with positive mean stress

Cited by 4 publications

References 21 publications

Initiation and short crack growth in austenitic–ferritic duplex steel‐effect of positive mean stress

Initiation and short crack growth in austenitic–ferritic duplex steel‐effect of positive mean stress

Analyzing the heat-treatment effect on the mechanical properties of free-cutting steels

Mechanical and functional fatigue of non-oriented and grain-oriented electrical steels

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