Discussion: “The Effect of Ausforming on the Rolling Contact Fatigue Life of a Typical Bearing Steel” (Bamberger, E. N., 1967, ASME J. Lubr. Technol., 89, pp. 63–72)

1967 ◽  
Vol 89 (1) ◽  
pp. 73-74 ◽  
Author(s):  
T. E. Tallian
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Contact Fatigue Life

The Effect of Ausforming on the Rolling Contact Fatigue Life of a Typical Bearing Steel

1967 ◽  
Vol 89 (1) ◽  
pp. 63-72 ◽  
Author(s):  
E. N. Bamberger
Keyword(s):  
Fatigue Life ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Development Program ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Metallurgical Analysis ◽  
Contact Fatigue Life ◽  
Life Improvement ◽  
Carbide Particles

A development program has been conducted on M-50 to determine the improvements possible in bearing steels by the incorporation of a hot-cold working (ausforming) treatment in their processing. Primary emphasis was on the improvements possible in rolling contact fatigue. In support of this, heat-treat, corrosion, hardness, and microstructural studies have been performed. It has been shown that a certain process for working steel in the metastable austenitic condition as applied to the rolling contact fatigue life of M-50 bearing steel will substantially improve life, thereby increasing bearing reliability. The remarkable improvements in life (exceeding 800 percent) will be a significant factor in meeting the long-life-bearing requirements for advanced air-breathing propulsion systems. A metallurgical analysis has been conducted and a mechanism is proposed which is thought to be the primary factor in providing the significant improvements in rolling contact fatigue life. It is shown that these improvements in life are possible without any significant increase in hardness of the subject materials. Evidence is presented which indicates that the life improvement is primarily due to more uniform carbide dispersion, reduction of massive carbide particles, and reduction in martensite platelet size. These microstructural changes are believed to be associated with strain-induced precipitation and its interplay with strain-hardening during the deformation cycle.

Improvement of Rolling Contact Fatigue Life of Bearing Steel by Quenching and Partitioning Process

2012 ◽  
Vol 706-709 ◽  
pp. 2152-2157 ◽  
Author(s):  
Kwan Ho Kim ◽  
Jae Seung Lee ◽  
Duk Lak Lee
Keyword(s):  
Fatigue Life ◽  
Silicon Content ◽  
Retained Austenite ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Quenching And Partitioning ◽  
Bearing Steels ◽  
Contact Fatigue Life

Over the decades, the rolling contact fatigue life of bearing steels has been enhanced mainly by the decrease in total oxygen content in the steels which was accomplished by improving steelmaking processes or facilities. However, it has almost been kept constant in the level of 5 ppm since 1990s and, therefore, it is necessary to find out other methods to enhance the RCFL. It is a well-known fact that the RCFL of bearing steels is maximized with the adequate amount of retained austenite and increasing silicon content results in the increase of the resistance to softening during tempering. In the present study, in order to take advantage of the effects of retained austenite and increasing silicon content, a new through-hardening heat treatment, quenching and partitioning (Q&P), has been chosen in place of the conventional quenching and tempering. One of the distinct differences between tempering and partitioning is no fine carbide precipitation during partitioning, leading to the stabilization of retained austenite due to the diffusion of carbon atoms from martensite, which can be realized by increasing silicon content. On the other hand, the increase of silicon content retarded the spheroidization behavior of cementites, requiring higher annealing temperature to assure the complete spheroidization. A new high carbon chromium bearing steel through-hardened by Q&P process showed superior RCFL characteristics to the conventional steel and process.

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