A repair process for fatigue damage using plasma nitriding

Alsaran, Akgün; Kaymaz, İrfan; Çelik, A.; Yetim, A.F.; Karakan, Mehmet

doi:10.1016/j.surfcoat.2003.12.017

Cited by 33 publications

(19 citation statements)

References 13 publications

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“…The lower temperature treated samples were clearly compromised by the much longer diffusion treatment time of 48 h. Finally, Ti-6Al-4V samples exhibiting the largest decline in fatigue limit (approximately 25%) were those treated at 900 1C for 2 h, when compared to untreated Ti-6Al-4V. The improved performance in fatigue life for the treatments performed at 800 1C (as opposed to treatments at 700 1C and 900 1C) is attributed to the increased build-up of compressive residual surface stresses at 800 1C which inhibit crack propagation by resisting cyclic slip [5,43]. Moreover, longer plasma nitriding durations have been associated with recrystallisation and grain growth -which may lead to premature failure, decreasing the overall fatigue life [5].…”

Section: Rotating-bending Fatigue Testingmentioning

confidence: 99%

“…For this reason thermochemical processes such as PIRAC nitrogen-diffusion may also be employed to interrupt the growth of nucleated cracks under the tensile part of the fatigue loading cycle. In fact, this effect (linked to the creation of surface compressive stresses) suppresses the propagation of surface-initiated cracks to the subsurface [43,47]. In the event that a surface crack progresses to the interior, it can otherwise cross grain boundaries unhindered, by changing from one slip system to another according to the new grain orientation [48].…”

Section: Rotating-bending Fatigue Testingmentioning

confidence: 99%

“…Particularly, in the HCF regime, fatigue strength is known to diminish drastically with increasing grain size due to premature and sudden crack formation [17]. Thermochemical processes such as nitriding and mechanical surface treatments such as shot peening, ball-burnishing and rollerburnishing are known to induce subsurface crack nucleation [43,53,54]. These form as a result of tensile stresses in the treatment/substrate interfacial regions, which balance out the compressive residual stresses induced in the surface by the diffusion process.…”

Section: Fracture Topographymentioning

confidence: 99%

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Evaluating the effects of PIRAC nitrogen-diffusion treatments on the mechanical performance of Ti–6Al–4V alloy

Bonello

Wilson

Housden

et al. 2014

Materials Science and Engineering: A

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a b s t r a c tPowder Immersion Reaction Assisted Coating (PIRAC) is a relatively simple nitrogen diffusion based process which has been proposed as a technique capable of considerable improvements in the tribological performance of ceramics and metals alike; however, the necessary exposure of the substrate material to high temperatures for several hours may have an adverse effect on the bulk properties of materials such as titanium alloys. The effect of PIRAC treatments on the bulk metallography and mechanical properties of Ti-6Al-4V has been studied. Following PIRAC nitrogen-diffusion treatment, studies using X-ray diffraction and cross-sectional microscopy have shown evidence of the formation of a thin ( $ 1.4 mm) TiN/Ti 2 N layer, together with the presence of some Ti 3 Al intermetallic phase. Semilogarithmic S-N plots show a deleterious effect after PIRAC treatment in terms of material cyclic fatigue strength, particularly at higher treatment temperatures. Samples processed at 800 1C for 4 h however exhibit better fatigue performance than others treated at lower temperatures for longer nitriding times. Fractographic inspection has shown that fatigue cracks originate at (or near) the surface for the untreated Ti-alloy and from the subsurface regions following diffusion treatment, owing to the build-up of compressive stresses in the latter, which hinder crack propagation.

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Section: Rotating-bending Fatigue Testingmentioning

confidence: 99%

Section: Rotating-bending Fatigue Testingmentioning

confidence: 99%

Section: Fracture Topographymentioning

confidence: 99%

See 1 more Smart Citation

Evaluating the effects of PIRAC nitrogen-diffusion treatments on the mechanical performance of Ti–6Al–4V alloy

Bonello

Wilson

Housden

et al. 2014

Materials Science and Engineering: A

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“…The effect of surface treatment after cyclic prestraining on the fatigue strength is noted in Ref. 18. An increase in the characteristics of high-cycle fatigue resistance of AISI 4140 steel specimens took place after plasma nitriding of the initial specimen and the specimen cyclically prestrained to 30% of its number of cycles to failure, as well as after re-nitridation following the cyclic prestraining to the same level.…”

Section: Introductionmentioning

confidence: 98%

The effect of PVD coatings on the tensile strength and low-cycle fatigue resistance of stainless steel and titanium alloys

Gopkalo

Rutkovskyy

2011

Fatigue &Amp; Fracture of Engineering Materials &Amp; Structures

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A B S T R A C T PVD coatings applied to components form hard, stronger layers and generate high residual compressive stresses that limit the plastic deformation in surface layers of the base metal thus increasing its tensile strength and resistance to fatigue loading. The purpose of this paper is to experimentally determine the influence of the deposition of 2 to 16.5-μm-thick PVD coatings of TiN , Cr, (Cr+TiN), (TiC)N, (TiAl)N onto specimens of stainless steel 321 and titanium alloys of types MILT-81556A and (10-2-3; 4966) on their tensile strength and low-cycle fatigue resistance when the development of large elastic-plastic strains takes place. The tensile and low-cycle fatigue tests were conducted under conditions of axial zero-to-tension cycle of the stress-controlled loading on flat 1-to 1.5-mm-thick specimens in the initial state (uncoated specimens) and after application of a PVD coating, including those after pretensioning or after cyclic prestraining in the low-cycle fatigue range. The deposition of PVD coatings is found to enhance the characteristics of tensile strength and low-cycle fatigue resistance in the quasi-static fracture range. The deposition of PVD coatings on specimens cyclically prestrained to the values of 53-86% of the number of cycles to fracture, changes the cyclic properties of the material and predetermines the fatigue fracture mode only.

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“…However, due to the depth limitation, the orthopedics treated in such a way is quite costly and still the lifetime is limited. Since plasma assisted thermo chemical surface treatments improve wear, corrosion resistance and fatigue strength, the plasma nitriding or carburising CoCrMo alloy may be beneficial for the medical application [11][12][13]. But no much study about the plasma nitriding CoCrMo alloy is reported [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%