Quantitative Analysis of Inclusion Engineering on the Fatigue Property Improvement of Bearing Steel

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Researchers

Research units

  • University of Science and Technology Beijing

Abstract

The fatigue property is significantly affected by the inner inclusions in steel. Due to the inhomogeneity of inclusion distribution in the micro-scale, it is not straightforward to quantify the effect of inclusions on fatigue behavior. Various investigations have been performed to correlate the inclusion characteristics, such as inclusion fraction, size, and composition, with fatigue life. However, these studies are generally based on vast types of steels and even for a similar steel grade, the alloy concept and microstructure information can still be of non-negligible difference. For a quantitative analysis of the fatigue life improvement with respect to the inclusion engineering, a systematic and carefully designed study is still needed to explore the engineering dimensions of inclusions. Therefore, in this study, three types of bearing steels with inclusions of the same types, but different sizes and amounts, were produced with 50 kg hot state experiments. The following forging and heat treatment procedures were kept consistent to ensure that the only controlled variable is inclusion. The fatigue properties were compared and the inclusions that triggered the fatigue cracks were analyzed to deduce the critical sizes of inclusions in terms of fatigue failure. The results show that the critical sizes of different inclusion types vary in bearing steels. The critical size of the spinel is 8.5 μm and the critical size of the calcium aluminate is 13.5 μm under the fatigue stress of 1200 MPa. In addition, with the increase of the cleanliness of bearing steels, the improvement of fatigue properties will reach saturation. Under this condition, further increasing of the cleanliness of the bearing steel will not contribute to the improvement of fatigue property for the investigated alloy and process design.

Details

Original languageEnglish
Article number476
Number of pages15
JournalMetals
Volume9
Issue number4
Publication statusPublished - 1 Apr 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • inclusion engineering, fatigue property, bearing steel, total oxygen content, HIGH-STRENGTH STEELS, REGIME N-GREATER-THAN-10(7) CYCLES, CRACK INITIATION, HYDROGEN EMBRITTLEMENT, CALCIUM TREATMENT, SLAG COMPOSITION, FAILURE, MECHANISM, BEHAVIOR

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