The mechanism of oxide inclusions in fatigue crack initiation in the very-high cycle fatigue (VHCF) regime was clarified by subjecting bearing steels deoxidized by Al (Al-deoxidized steel) and Si (Si-deoxidized steel) to ultrasonic tension-compression fatigue tests (stress ratio, R = −1) and analyzing the characteristics of the detected inclusions. Results show that the main types of inclusions in Si- and Al-deoxidized steels are silicate and calcium aluminate, respectively. The content of calcium aluminate inclusions larger than 15 µm in Si-deoxidized steel is lower than that in Al-deoxidized steel, and the difference observed may be attributed to different inclusion generation processes during melting. Despite differences in their cleanliness and total oxygen contents, the Si- and Al-deoxidized steels show similar VHCF lives. The factors causing fatigue failure in these steels reveal distinct differences. Calcium aluminate inclusions are responsible for the cracks in Al-deoxidized steel. By comparison, most fatigue cracks in Si-deoxidized steel are triggered by the inhomogeneity of a steel matrix, which indicates that the damage mechanisms of the steel matrix can be a critical issue for this type of steel. A minor portion of the cracks in Si-deoxidized steel could be attributed to different types of inclusions. The mechanisms of fatigue fracture caused by calcium aluminate and silicate inclusions were further analyzed. Calcium aluminate inclusions first separate from the steel matrix and then trigger crack generation. Silicate inclusions and the steel matrix are closely combined in a fatigue process; thus, these inclusions have mild effects on the fatigue life of bearing steels. Si/Mn deoxidation is an effective method to produce high-quality bearing steel with a long fatigue life and good liquid steel fluidity.

通过对Al（Al脱氧钢）和Si（Si脱氧钢）脱氧的轴承钢进行超声张力压缩疲劳试验，阐明了超高循环疲劳（VHCF）疲劳裂纹萌生中氧化物夹杂物的形成机理。 （应力比，R= -1）并分析检测到的夹杂物的特征。结果表明，硅和铝脱氧钢中夹杂物的主要类型分别为硅酸盐和铝酸钙。Si脱氧钢中大于15 µm的铝酸钙夹杂物含量低于Al脱氧钢，观察到的差异可能归因于熔化过程中夹杂物的产生过程不同。尽管在清洁度和总氧含量上存在差异，但Si和Al脱氧的钢仍具有相似的VHCF寿命。这些钢中引起疲劳破坏的因素显示出明显的差异。铝酸钙夹杂物是造成铝脱氧钢中裂纹的原因。相比之下，硅脱氧钢中的大多数疲劳裂纹是由钢基体的不均匀性引起的，这表明钢基质的损伤机理可能是这类钢的关键问题。硅脱氧钢中的一小部分裂纹可归因于不同类型的夹杂物。进一步分析了铝酸钙和硅酸盐夹杂物引起的疲劳断裂机理。铝酸钙夹杂物首先从钢基质中分离出来，然后引发裂纹的产生。硅酸盐夹杂物和钢基质在疲劳过程中紧密结合。因此，这些夹杂物对轴承钢的疲劳寿命有轻微的影响。Si / Mn脱氧是生产具有长疲劳寿命和良好钢液流动性的高质量轴承钢的有效方法。硅脱氧钢中的一小部分裂纹可归因于不同类型的夹杂物。进一步分析了铝酸钙和硅酸盐夹杂物引起的疲劳断裂机理。铝酸钙夹杂物首先从钢基质中分离出来，然后引发裂纹的产生。硅酸盐夹杂物和钢基质在疲劳过程中紧密结合。因此，这些夹杂物对轴承钢的疲劳寿命有轻微的影响。Si / Mn脱氧是生产具有长疲劳寿命和良好钢液流动性的高质量轴承钢的有效方法。硅脱氧钢中的一小部分裂纹可归因于不同类型的夹杂物。进一步分析了铝酸钙和硅酸盐夹杂物引起的疲劳断裂机理。铝酸钙夹杂物首先从钢基质中分离出来，然后引发裂纹的产生。硅酸盐夹杂物和钢基质在疲劳过程中紧密结合。因此，这些夹杂物对轴承钢的疲劳寿命有轻微的影响。Si / Mn脱氧是生产具有长疲劳寿命和良好钢液流动性的高质量轴承钢的有效方法。铝酸钙夹杂物首先从钢基质中分离出来，然后引发裂纹的产生。硅酸盐夹杂物和钢基质在疲劳过程中紧密结合。因此，这些夹杂物对轴承钢的疲劳寿命有轻微的影响。Si / Mn脱氧是生产具有长疲劳寿命和良好钢液流动性的高质量轴承钢的有效方法。铝酸钙夹杂物首先从钢基质中分离出来，然后引发裂纹的产生。硅酸盐夹杂物和钢基质在疲劳过程中紧密结合。因此，这些夹杂物对轴承钢的疲劳寿命有轻微的影响。Si / Mn脱氧是生产具有长疲劳寿命和良好钢液流动性的高质量轴承钢的有效方法。