Record Details

Microstructural and Material Quality Effects on Rolling Contact Fatigue of Highly Elastic Intermetallic NiTi Ball Bearings
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Author and Affiliation:
Dellacorte, Christopher(NASA Glenn Research Center, Cleveland, OH United States);
Howard, S. Adam(NASA Glenn Research Center, Cleveland, OH United States);
Thomas, Fransua(NASA Glenn Research Center, Cleveland, OH United States);
Stanford, Malcolm K.(NASA Glenn Research Center, Cleveland, OH United States)
Abstract: Rolling element bearings made from highly-elastic intermetallic materials (HIM)s, such as 60NiTi, are under development for applications that require superior corrosion and shock resistance. Compared to steel, intermetallics have been shown to have much lower rolling contact fatigue (RCF) stress capability in simplified 3-ball on rod (ASTM STP 771) fatigue tests. In the 3-ball tests, poor material quality and microstructural flaws negatively affect fatigue life but such relationships have not been established for full-scale 60NiTi bearings. In this paper, 3-ball-on-rod fatigue behavior of two quality grades of 60NiTi are compared to the fatigue life of full-scale 50mm bore ball bearings made from the same materials. 60NiTi RCF rods with material or microstructural flaws suffered from infant mortality failures at all tested stress levels while high quality 60NiTi rods exhibited no failures at lower stress levels. Similarly, tests of full-scale bearings made from flawed materials exhibited early surface fatigue and through crack type failures while bearings made from high quality material did not fail even in long-term tests. Though the full-scale bearing test data is yet preliminary, the results suggest that the simplified RCF test is a good qualitative predictor of bearing performance. These results provide guidance for materials development and to establish minimum quality levels required for successful bearing operation and life.
Publication Date: Mar 01, 2017
Document ID:
20170002297
(Acquired Mar 17, 2017)
Subject Category: METALS AND METALLIC MATERIALS; MECHANICAL ENGINEERING
Report/Patent Number: NASA/TM-2017-219466, E-19341, GRC-E-DAA-TN38995
Document Type: Technical Report
Contract/Grant/Task Num: WBS 401769.06.01.01.06
Financial Sponsor: NASA Glenn Research Center; Cleveland, OH United States
Organization Source: NASA Glenn Research Center; Cleveland, OH United States
Description: 22p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: BALL BEARINGS; FATIGUE TESTS; INTERMETALLICS; MICROSTRUCTURE; BINARY ALLOYS; FATIGUE LIFE; NICKEL ALLOYS; TITANIUM ALLOYS; SHOCK RESISTANCE; CORROSION RESISTANCE; FAILURE; CRACKS; DEFECTS; STEELS
Other Descriptors: BEARINGS; METALS; TRIBOLOGY
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