An analytical calculation method of the load distribution and stiffness of an angular contact ball bearing

In resulfurized special steel, MnS and Al2O3 are two main inclusions that deteriorate fatigue life and machinability. It is important that these two inclusions should be well controlled to increase steel quality and usage performance. In the present study, a Mg–Ca treatment was employed to modify the MnS and Al2O3 inclusions in resulfurized steels to reduce detrimental effects on fatigue life and machinability. In the laboratory study, Ni–Mg alloy was added to 16MnCrS5 and 49MnVS3 steels. Both Al2O3 and CaO–Al2O3 were gradually modified to MgO·Al2O3 and MgO, being surrounded by MnS, that is, a complex inclusion with an oxide core and sulfide outer layer was formed. The amount of the complex inclusion increased with Mg content. In the hot forging experiment, non-Mg treated inclusions were in the morphology of long strip, while those with Mg treatment were seen to be less deformed with spherical morphology of low aspect ratio in which case inclusions had less effect on steel mechanical properties. The Mg–Ca treatment was also applied to the manufacture of resulfurized special steel in steel plants. The scanning electron microscope–energy dispersive spectrometer and statistical results agreed well with those in the laboratory studies.

https://www.mdpi.com/1996-1944/12/2/197/pdf

Morphology Study on Inclusion Modifications Using Mg⁻Ca Treatment in Resulfurized Special Steel

An analytical method for dynamic analysis of a ball bearing with offset and bias local defects in the outer race

A quantitatively distributed wear-measurement method for spur gears during micro-pitting and pitting tests

A tribo-dynamic based pitting evolution model of planetary gear sets: A topographical updating approach

A model to predict initiation and propagation of micro-pitting on tooth flanks of spur gears

The evaluation of wear progress of gear tooth flanks made of 16MnCr5 was performed using non-destructive micro-magnetic testing, specifically Barkhausen noise (BN) and incremental permeability (IP). Based on the physical interaction of the microstructure with the magnetic field, the micro-magnetic characterization allowed the analysis of changes of microstructure caused by wear, including phase transformation and development of residual stresses. Due to wide parameter variation and application of bandpass filter frequencies of micro-magnetic signals, it was possible to indicate and separate the main damage mechanisms considering the wear development. It could be shown that the maximum amplitude of BN correlates directly with the profile form deviation and increases with the progress of wear. Surface investigations via optical and scanning electron microscopy indicated strong surface fatigue wear with micro-pitting and micro-cracks, evident in cross-section after 3 × 10⁵ cycles. The result of fatigue on the surface layer was the decrease of residual compression stresses, which was indicated by means of coercivity by BN-analysis. The different topographies of the surfaces, characterized via confocal white light microscopy, were also reflected in maximum BN-amplitude. Using complementary microscopic characterization in the cross-section, a strong correlation between micro-magnetic parameters and microstructure was confirmed and wear progress was characterized in dependence of depth under the wear surface. The phase transformation of retained austenite into martensite according to wear development, measured by means of X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) was also detected by micro-magnetic testing by IP-analysis.

/pdf/micro-magnetic-and-microstructural-characterization-of-wear-4bblh1g8es.pdf

Micro-Magnetic and Microstructural Characterization of Wear Progress on Case-Hardened 16MnCr5 Gear Wheels.

Micro-magnetic testing methods are qualified for non-destructive quantification of hardness, hardness depth and residual stresses. Among others they are applied for detection of grinding burn in gear wheels, but an application for wear condition monitoring has not yet been published. In this paper, results of initial research of determination of wear condition in gear wheels by application of micro-magnetic testing systems are presented. For comparison of different wear conditions, gears were loaded for increasing numbers of cycles in a test rig based on FVA information sheet 54/7 and DIN ISO 14635 part 1. Operating conditions were altered by usage of different lubricants. Afterwards, wear conditions were determined by conventional techniques, i. e., measuring change in profile and loss of material. Four measurement principles were evaluated for change in micro-magnetic properties determination, magnetic Barkhausen noise analysis, permeability and eddy-current measurements, as well as harmonic an...

Max Weibring

Papers

A model to predict initiation and propagation of micro-pitting on tooth flanks of spur gears

Micro-Magnetic and Microstructural Characterization of Wear Progress on Case-Hardened 16MnCr5 Gear Wheels.

Application of micro-magnetic testing systems for non-destructive analysis of wear progress in case-hardened 16MnCr5 gear wheels