Rolling Contact Fatigue of Hot-Forged Steels out of Prealloyed Powders and Powder Blend

2007 ◽  
Vol 534-536 ◽  
pp. 709-712
Author(s):  
Vladimir Dorofeyev ◽  
Anna Sviridova
Keyword(s):  
Thermomechanical Treatment ◽  
Rolling Contact Fatigue ◽  
Hot Forging ◽  
Contact Fatigue ◽  
Steel Structure ◽  
Rolling Contact ◽  
Metastable Austenite ◽  
Practical Utilization ◽  
Metallic Inclusions ◽  
Optimal Values

Powder forging is used for heavy-loaded parts (rings of rolling-contact bearings, gears etc.) production. Rolling contact fatigue is material property values of which characterize possibility of practical utilization of such parts. Rolling contact fatigue of some steels obtained out of prealloyed powders Astaloy CrM, Atomet 4601, Atomet 4901 and powder blends iron-carbon-nickel by hot forging is studied in the present paper. Effect of various kinds of heat and thermomechanical treatment on rolling contact fatigue is determined. Thermomechanical treatment provides optimal values of rolling contact fatigue. In this case steel structure contains up to 40% of retained metastable austenite which is transformed to martensite on trials. Thus typically crack is generated on residual pores and non-metallic inclusions instead of martensite zones in wrought steels.

Paper 10: Metallurgical Aspects of Rolling Contact Fatigue

1966 ◽  
Vol 181 (15) ◽  
pp. 94-103 ◽  
Author(s):  
D. Scott ◽  
B. Loy ◽  
G. H. Mills
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Contributory Factor ◽  
Surface Material ◽  
Dominant Effect ◽  
Dominant Mechanism ◽  
Metallic Inclusions ◽  
Catastrophic Fracture ◽  
Mechanism Of Failure

Metallurgical investigations aided by electron microscopy and associated techniques have been carried out on failed test specimens and bearings from service, to obtain information of use in the elucidation of the mechanisms of failure. Investigations have revealed that cracks initiating rolling contact fatigue can start at the surface and spread into the material, or start below the surface and spread outwards, the more dominant mechanism depending upon prevailing circumstances. Metallographic changes in surface material owing to rolling and sliding action, and subsurface microstructural changes at depths associated with the region of maximum Hertzian shearing stress can influence the mechanism of failure. Environment can affect the rate of crack propagation and mode of fracture; hydrogen embrittlement can be a contributory factor in catastrophic fracture, and non-metallic inclusions can have a dominant effect on the incidence of failure.

The Effect of Isothermal Heat Treatment on the Rolling Contact Fatigue of Carburized Low Carbon Microalloyed Steel

2007 ◽  
Vol 544-545 ◽  
pp. 151-154
Author(s):  
Jae Seong Lee ◽  
Bok Han Song ◽  
H. G. Sung ◽  
S. Y. Kim ◽  
Bo Young Hur
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Microalloyed Steel ◽  
Rolling Contact Fatigue ◽  
Hot Forging ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Isothermal Heat Treatment ◽  
Low Carbon ◽  
Austenite Grain

In case of the low carbon chromium steel that have widely been used for the carburized gears or rolling bearings, the austenite grain coarsening may be occasionally occurred during carburizing. To restrain this phenomenon, most of hot forged parts have been given to an isothermal heat treatment or normalizing immediately after hot forging and/or prior to carburizing. Therefore, their production cost includes unexpected additional expenses caused by such a non-value added process. To confirm the possibility of an energy saving, as well as attaining a superior fatigue life, in the production of automotive parts to be carburized, the austenite grain coarsening with the manufacturing process of the microalloyed steel, containing Nb and B as a grain refining elements, was investigated. The heat treatment characteristics and rolling contact fatigue behavior of the carburized specimens with the isothermal heat treatment were also investigated. In spite of omitting the isothermal heat treatment after hot forging, the abnormally coarse austenite grains were not found out in the carburized specimens. However, the rolling contact fatigue life of the carburized specimens, in which the isothermal heat treatment was omitted, was shorter than that of isothermally heat-treated specimens.

Observation of Crack Originating from Non-Metallic Inclusions in Furnace-Induction Heated SUJ2 Steel under One-Point Rolling Contact Fatigue at High Contact Pressure

2021 ◽  
Vol 1033 ◽  
pp. 3-7
Author(s):  
Koshiro Mizobe ◽  
Yuto Nakamura ◽  
Yuki Yano ◽  
Takahiro Matsueda ◽  
Katsuyuki Kida
Keyword(s):  
Crack Growth ◽  
Contact Pressure ◽  
Cross Sections ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Tests ◽  
Rolling Contact ◽  
Hardness Distribution ◽  
Metallic Inclusions ◽  
High Contact Pressure

It is important to reveal the mechanism of crack growth from non-metallic inclusions because it commonly causes the origin of flaking fracture. In order to observe the cracks initiated from non-metallic inclusions under contact pressure, we performed one-point rolling contact fatigue tests using furnace-induction heated SUJ2 steel. We measured the hardness distribution of the furnace-induction heated (FIH) specimen and observed cracks with the inclusions at cross-sections.

Crack Initiation Observation in Early Stage of Rolling Contact Fatigue of SUJ2 Using a Single-Ball Apparatus

2014 ◽  
Vol 620 ◽  
pp. 421-424
Author(s):  
Katsuyuki Kida ◽  
Shintaro Hazeyama ◽  
Takuma Sado ◽  
Koshiro Mizobe ◽  
Takuya Shibukawa
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Crack Initiation ◽  
Early Stage ◽  
Rolling Contact Fatigue ◽  
Testing Machine ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Metallic Inclusions ◽  
Full Cross Section

A single-ball RCF testing machine was used in order to investigate crack initiation of SUJ2 material at early stage of fatigue. This machine enables observation of a full cross section by sectioning the specimen only once. The RCF tests were carried out under a Hertzian stress of 5.3 GPa, at 3000 rpm. All of the cracks initiated from non-metallic inclusions on 300 mm2sized area were counted, and the relation between the number of cracks and their initiation depths was drawn. Furthermore subsurface shear stress distribution was calculated. Empirical data of the crack distributions and subsurface stress distribution was compared. It was found that the crack starts growing during 3.3×104- 1.0×105cycles by the subsurface shear stress.

The Microstructure Control and Rolling Contact Fatigue Behavior of a Hot Worked Automotive Application

Materials ◽  
2005 ◽  
Author(s):  
Jae-Seong Lee ◽  
Chan-Hyun Son ◽  
Bok-Han Song ◽  
Hyo-Seup Han
Keyword(s):  
Grain Size ◽  
Fatigue Resistance ◽  
Fatigue Behavior ◽  
Rolling Contact Fatigue ◽  
Hot Forging ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Automotive Application ◽  
Contact Fatigue Resistance ◽  
Ferrite Grain Size

Once hot forgings for automotive parts such as wheel bearing flange to which cyclic asymmetric bending stress is continuously applied are produced, their microstructure, such as ferrite, should be controlled appropriately for obtaining of superior mechanical properties. However, it is hard to control the microstructure uniformly because mechanical strength is reduced as coarsening of ferrite grains. To investigate the microstructural alteration based on process parameters during hot working, the variation of the ferrite grain size, hereafter FGS, was investigated by utilizing of the computer-controlled servo-hydraulic Gleeble tester which can reproduce hot deformation behavior. In addition, the effect of ferrite grain size of raw material on austenite grain behavior of hot forgings was also examined. The rolling contact fatigue resistance of induction-hardened SAE1055 steel was compared with the result of induction-hardened SAE52100 bearing steel. As a result, it was confirmed that ferrite grain sizes of hot forging depend on heating temperature and cooling-start temperature during hot forging and cooling operations. Induction-hardened SAE1055 steel showed superior rolling contact fatigue resistance to induction-hardened SAE52100 steel. This fact appears that SAE1055 steel is freer from material defects such as segregateion than comparative steel.

Rolling Contact Fatigue of Wheel and Rail

2012 ◽  
Vol 54 (5) ◽  
pp. 304-312
Author(s):  
Florian Dörner ◽  
Otto Kleiner ◽  
Christian Schindler ◽  
Peter Starke ◽  
Dietmar Eifler
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact
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