TY - THES

T1 - Fretting Wear and Fretting Fatigue of Ti-6Al-4V

AU - Juric, Josip

N1 - embargoed until null

PY - 2010

Y1 - 2010

N2 - Titanium alloys and especially Ti-6Al-4V combine good mechanical properties such as high strength and excellent corrosion resistance with low density. The examples of applications have a wide range, from medical and automotive to aerospace engineering. Using more and more lightweight components for reduction of weight and increase of capacity leads to reduced stiffness, augmented oscillatory movements between contact surfaces, and finally to fretting damage. The fretting behavior of the titanium alloy Ti-6Al-4V was characterized with fretting wear and fretting fatigue tests. Fretting wear tests were performed to characterize the wear behavior in respect of varying parameters such as contact pressure, relative amplitude and fretting cycles. Based on fretting tests at different temperatures caused by varying testing frequencies, the influence of temperature on fretting behavior was investigated. Fretting fatigue test were conducted to determine the reduction of durability in comparison to plain fatigue tests. Furthermore, the influence of different Ti-6Al-4V microstructures on fretting wear and fretting fatigue life was investigated. Fretting wear tests showed that with increasing fretting cycles or relative amplitude, the wear mass increases, whereas no influence of the contact pressure was observed. A comparison of different Ti-6Al-4V microstructures revealed, that the bimodal microstructure has the highest wear resistance. Fretting fatigue tests showed an essential reduction of durability due to fretting conditions in comparison to plain fatigue tests. The highest fretting fatigue strength of all investigated microstructures was determined for the mill-annealed microstructure. The fretting fatigue strength of Ti-6Al-4V was estimated with existing fatigue models and the aid of finite element analysis. It was observed, that the equivalent stresses in the fretting contact were responsible for the fretting fatigue damage. They cause a local low cycle fatigue loading in spite of the global high cycle fatigue load of the specimen. The performed fretting tests and the detailed analysis are the basis for the inclusion of the fretting damage in lifetime estimation of Ti-6Al-4V components.

AB - Titanium alloys and especially Ti-6Al-4V combine good mechanical properties such as high strength and excellent corrosion resistance with low density. The examples of applications have a wide range, from medical and automotive to aerospace engineering. Using more and more lightweight components for reduction of weight and increase of capacity leads to reduced stiffness, augmented oscillatory movements between contact surfaces, and finally to fretting damage. The fretting behavior of the titanium alloy Ti-6Al-4V was characterized with fretting wear and fretting fatigue tests. Fretting wear tests were performed to characterize the wear behavior in respect of varying parameters such as contact pressure, relative amplitude and fretting cycles. Based on fretting tests at different temperatures caused by varying testing frequencies, the influence of temperature on fretting behavior was investigated. Fretting fatigue test were conducted to determine the reduction of durability in comparison to plain fatigue tests. Furthermore, the influence of different Ti-6Al-4V microstructures on fretting wear and fretting fatigue life was investigated. Fretting wear tests showed that with increasing fretting cycles or relative amplitude, the wear mass increases, whereas no influence of the contact pressure was observed. A comparison of different Ti-6Al-4V microstructures revealed, that the bimodal microstructure has the highest wear resistance. Fretting fatigue tests showed an essential reduction of durability due to fretting conditions in comparison to plain fatigue tests. The highest fretting fatigue strength of all investigated microstructures was determined for the mill-annealed microstructure. The fretting fatigue strength of Ti-6Al-4V was estimated with existing fatigue models and the aid of finite element analysis. It was observed, that the equivalent stresses in the fretting contact were responsible for the fretting fatigue damage. They cause a local low cycle fatigue loading in spite of the global high cycle fatigue load of the specimen. The performed fretting tests and the detailed analysis are the basis for the inclusion of the fretting damage in lifetime estimation of Ti-6Al-4V components.

KW - Fretting-Fatigue Fretting-Wear Ti-6Al-4V Mikrostruktur

KW - Fretting wear fretting fatigue Ti-6Al-4V microstructure

M3 - Diploma Thesis

ER -