Wyniki wyszukiwania - BazTech

1

Effect of burnishing on the contact fatigue of regenerative thermally sprayed coatings

Starosta R.

Journal of KONES

|

2013

|

Vol. 20, No. 1

309--315

EN

This study of the resistance to contact fatigue of Ni-5%Al alloy coatings and Ni-5%Al-15%Al2O3 composite coatings were evaluated. The coatings were prepared by flame spraying (Casto-Dyn DS 8000 torch) and plasma spraying (PN 120 plasma jet). The coatings were subjected to a finishing treatment: turning, burnishing and grinding. Depending on coatings phase composition and finishing treatment, the parameter mean values of surface roughness (Ra) were in the wide range of 0.28 to 2.61 􀁐m. The coatings after burnishing characterized by smallest of surface roughness. The largest value of the parameter Ra was observed in the case of coatings after turning. The presence of the reinforcing phase in the coating increases the surface roughness of thermally sprayed composite coatings. The hardness of coatings also depends on the finishing methods. The minimum hardness equal to 192 HV2 was found in the case of coatings of Ni-5%Al obtained by using a Casto-Dyn DS 8000 gas torch. Burnished Ni-5%Al-15%Al2O3 coatings obtained by plasma spraying characterized by hardness 291 HV2. Resistance of fatigue surface of thermally sprayed coatings on a SCF (standing contact fatigue) test stand was assessed. The test was designed based on the guidelines of the PN-80/H-04324 Polish standard. During the fatigue tests were provided constant contact of co-acting parts, without slipping. Based on the survey it was found that the plasma sprayed coatings (PN120 plasma-jet) have a greater resistance to fatigue then the coatings obtained by flame spraying Casto-Dyn DS 8000 torch. Composite coatings of Ni-5%Al- 15%Al2O3 are more resistant to contact fatigue, compared to the alloy coatings of Ni-5%Al. Burnishing increases the fatigue resistance of coatings when compared to turning. Burnished and polished surfaces are characterized by a similar contact fatigue resistance.

2

Ocena trwałości eksploatacyjnej metodą stykowej wytrzymałości zmęczeniowej stali łożyskowej 100CrMnSi6-4

Jeleńkowski J., Rożniatowski K., Nakonieczny A.

Inżynieria Powierzchni

|

2012

|

nr 2

55-63

PL

W artykule zaprezentowano badania stykowej wytrzymałości zmęczeniowej stali łożyskowej l OOCrMnSi6-4, poddanej innowacyjnej obróbce cieplnej, w której dotychczasową standardową obróbkę cieplną zastąpiono hartowaniem izotermicznym. W miejsce nisko odpuszczonego martenzytu otrzymano mikrostrukturę złożoną z martenzytu, bainitu dolnego z midribami oraz austenitu szczątkowego. Temperaturę Ms dla nowych warunków obróbki cieplnej określano w badaniach dylatometrycznych. Mikrostrukturę stali obrazowano przy użyciu mikroskopu świetlnego i elektronowego mikroskopu skaningowego. Formy zużycia pittingowego obrazowano mikroskopem wyposażonym w kolorową kamerę cyfrową. Stwierdzono, że mikrostruktura zapewniająca najlepszą zmęczeniową wytrzymałość stykową badanej stali zawiera bainit dolny z midribami, tworzący się w zakresie temperaturowym najniższej trwałości przechłodzanego austenitu przy temperaturze niższej od Ms. Przemiana w tym zakresie temperaturowym rozdrabnia też istotnie strukturę stali. Badania stykowej wytrzymałości zmęczeniowej przeprowadzono w warunkach określonych normą.

EN

The article presents the contact fatigue strength testing of bearing steel 100CrMnSi6-4, subjected to an innovative heat treatment in which the current standard heat treatment was replaced by isothermal gueriching. In place of low-tempered martensite the microstructure consisting of martensite, lower bainite with midribs and retained austenite was obtained. Ms temperature for the new conditions of heat treatment was determined in dilatometric studies. Imaging of microstructure of steel was carried out using light microscope and scanning electron microscope. Forms of pitting wear were imaged by a microscope equipped with a colour digital camera. It was found that the microstructure providing the best contact fatigue strength of tested steel contained the lower bainite with midribs, which was formed in the temperature range of the lowest stability of under cooled austenite, at a temperature below the Ms. The transformation in this temperature range also significantly refines the structure of steel The contact fatigue tests were carried out under the conditions specified in proper standard.

3

Rolling contact fatigue of Ti64 bearings before and after laser gas nitriding

Santos E.C., Kida K., Rozwadowska J., Kashima Y.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2011

|

z. 99

50-52

EN

Due to their biocompatibility and high strength-to-weight ratio titanium and Ti alloys are widely used in high end application in the medical and aeronau- tical industries. The materials` low wear resistance presents a disadvantage that is approached in this work. In order to enhance the rolling contact fa- tigue properties of the bearings` working surface, a laser coating technique was used. Non-coated and coated specimens were tested in equal conditions and it was found that layers of titanium nitride significantly improve the rolling contact fatigue performance of titanium components.

4

The analysis of finish tooling influence on contact fatigue of steel applied to sea water pump shafts

Charchalis A., Starosta R., Labuda W.

Journal of KONES

|

2011

|

Vol. 18, No. 2

85-92

EN

The article presents the research results referring to the analysis of the influence of finish treatment (lathing, grinding, burnishing) on the contact fatigue of steel applied to marine pump shafts. The research was performed on a roller 25mm in diameter made of X5CrNi18-10 (AISI304 L) stainless steel. The lathing process was carried out by means of a Sandvik Coromant cutting too, the grinding was done by grinding attachment to a lathe, whereas the process of burnishing was performed by SRMD burnisher by Yamato. Within the research, the optimalization of burnishing technological parameters was conducted on account of the minimalization of Ra surface roughness coefficient as well as the maximalization of SU degree of surface layer relative hardness. The multi criteria optimalization conducted by min-max method with regard to minimum surface roughness as well as maximum degree of surface layer hardness demonstrated that burnishing process should be carried out at the following technological parameters: burnishing force 1.1 kN, burnishing speed 35 m/min, feed 0.13 mm/rev. In addition, the influence of the burnisher passes number on the surface layer quality was determined. It is essential for this research to determine the burnishing influence on the service conditions which comprises the electrochemical corrosion research, friction wear and contact fatigue research. The paper will present the research results of contact fatigue examination of samples after finish machining.

5

Zużycie i trwałość szyn kolejowych

Adamiec P., Dziubiński J., John A.

Przegląd Mechaniczny

|

2002

|

nr 7-8

54-58

PL

Zaproponowano metodykę oceny trwałości szyn, badano zużycie eksploatacyjne szyn twardych (332 HB) po obróbce cieplnej oraz szyn zwykłych (266 HB) bez obróbki cieplnej, analizowano zużycie ścierno-adhezyjne szyn oraz ich zużycie w efekcie zmęczenia kontaktowego, wyznaczono charakterystyki trwałościowe badanych szyn, wykorzystując pomiary zużycia szyn w torze na terenie Śląskiej DOKP; stwierdzono korzystny wpływ dużej twardości szyn na ich trwałość przy kryterium odporności na ścieranie, natomiast nie stwierdzono wpływu twardości szyn na ich odporność na zmęczenie kontaktowe.

EN

Methods of assessment of the life of rails. Service wear was examined of hard rails (332 HB) after heat treatment and common rails (266 HB) without heat treatment. Abrasive adhesive wear of the rails and their wear caused by contact fatigue were analysed. Life characteristics of the rails were determined on the basis of rail wear measurement in the Silesian railway system. Positive influence is found of high hardness or the rails upon their life at a abrasion resistance criterion, while no influence is found of the rail hardness upon their contact fatigue resistance.