Thermal fatigue resistance of gas and plasma nitrided 41CrAlMo7 steel

Pellizzari, M.; Molinari, A.; Straffelini, Giovanni

doi:10.1016/s0921-5093(02)00867-5

Cited by 73 publications

(49 citation statements)

References 14 publications

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“…In the literature we can find contradictory result regarding to the thermal fatigue resistance of some nitrided surfaces. Thus Pellizari et al [8] claim that nitrided surfaces decreased the fatigue resistance on the contrary Spies et al [9] claim that the nitrided surface increased fatigue resistance. The authors did not present the temperature field and consequently they also could not calculate (asses) the stress field (predominately tensile or compression stresses) on the tested specimens from which the reason for the appearance of cracks based.…”

Section: Discussionmentioning

confidence: 99%

A newly developed test rig for the study of thermal fatigue

Fazarinc¹,

Turk²,

Kugler³

et al. 2007

WIT Transactions on Modelling and Simulation, Vol 46

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For simulation and better study of thermal fatigue, a new test rig has been developed. The rig has computer guided heating and quenching of the specimen that enables constant thermal loading and gathering of reliable experimental data. At the same maximal testing temperature it is possible to generate different and higher temperature gradients in comparison to other tests. The cooling rates that were measured were almost 4000 °C/s, which is considerably higher than the known rates so far measured (calculated) in cases of thermal fatigue cases (500-1000 °C) and thus fewer cycles to crack nucleation were needed. Verification of the abilities of the rig was carried out with specimens (AISI H11 tool steel) which had different wall thicknesses (2.75-4 mm) and different surface qualities (heat treated and gas nitrided). The gas nitrided specimens exhibited lower thermal fatigue resistance. The shape of cracks was a grid, which is a typical characteristic of tools subjected to thermal fatigue (tools for hot forming of materials, etc.). Some specimens were additionally mechanically loaded and cracks that were at right-angles to the direction of the compression force were essentially detained; their nucleation and growth were suppressed. The measured temperatures in the surface layer were used to calculate the initial stress field using the Finite Element Method (FEM). The computed results matched well with the experimental data on the number of cycles needed for crack initiation.

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Section: Discussionmentioning

confidence: 99%

A newly developed test rig for the study of thermal fatigue

Fazarinc¹,

Turk²,

Kugler³

et al. 2007

WIT Transactions on Modelling and Simulation, Vol 46

View full text Add to dashboard Cite

show abstract

“…[3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Several research works related to thermal fatigue resistance of die materials (i.e. steels, cast irons) were carried out where reasons for initiation and growth of cracks at hot working dies (forging, die casting) [17][18][19][20][21][22][23][24][25][26][27][28][29][30] and hot working rolls [3][4][5][6]9,[31][32][33][34] were investigated using various laboratory tests. However, detailed knowledge about the influence of the stress state, the temperature and the oxidation on the initiation and propagation of thermal cracks in hot working applications is still lacking.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of the thermal fatigue resistance for 3.1C, 0.8Si, 0.9Mn, 1.7Cr, 4.5Ni and 0.3Mo ICDP cast iron roll at 600 °C

Terčelj¹,

Fajfar²,

Godec³

et al. 2017

Mater. Tehnol.

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Using a new test rig the characteristics related to the thermal fatigue resistance for ICDP (Indefinite Chill Double Pour) cast iron for hot working rolls was investigated. Tests were carried out at 600°C to obtain the characteristics of cracks at (500, 1000 and 1500) cycles. For comparative purposes, additionally a test at 500°C was carried out. The average length of all the cracks, their density, average length of five longest cracks and relevant microstructural characteristics for the mentioned cycles were determined. It was found that the cracks initiation and their growth are related to the cracking and spalling of the carbides, shape of graphite, distribution of carbides and graphite particles, oxidation, etc. The obtained results contribute to a better understanding of the thermal cracking of selected roll cast iron. Based on these results the suggestions for improving the thermal fatigue resistance for the cast iron roll are given. Keywords: roll cast iron, thermal fatigue, cementite, graphite, cracks Novo razvita naprava je bila uporabljena za raziskave lastnosti ICDP litega`eleza, ki so povezane z odpornostjo na termi~no utrujanjem. Zna~ilnosti razpok so bile dolo~ene po (500, 1000 in 1500) ciklih, pri 600°C. Za primerjavo je bilo izvedenih nekaj testiranj tudi pri 500°C. Na osnovi rezultatov testiranj je bilo za vsako {tevilo ciklov dolo~ena povpre~na dol`ina vseh dobljenih razpok, njihova gostota, povpre~na dol`ina petih najdalj{ih razpok, vklju~no z ostalimi relevantnimi mikrostrukturnimi zna~ilnostmi. Rezultati so pokazali, da sta nukleacija in rast razpok tesno povezana s pokanjem in drobljenjem karbidov, z geometrijo grafita, z volumsko porazdelitvijo karbidov ter grafitnih delcev, z oksidacijo, itd. Rezultati prispevajo k bolj{emu razumevanju termi~nega pokanja izbranega materiala za valje. Na osnovi predstavljenih rezultatov so podani predlogi za izbolj{anje odpornosti litega`eleza za valje na termi~no utrujanje.

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“…Nitriding is a thermochemical surface-treatment process of ferritic steel components in order to improve properties such as the resistances against fatigue, corrosion and wear [1][2][3][4][5][6][7]. In order to introduce nitrogen into the component, gaseous nitriding, employing NH 3 -based atmospheres, is widely adopted.…”

Section: Introductionmentioning

confidence: 99%