Rolling bearing and large inclusions evaluation method, and its bearing steel

摘要

It is primarily intended to provide a large inclusions evaluation method of bearing steel can be evaluated quantitatively large inclusions even at high cleanliness. Another object of the second to provide a suitable bearing steel is evaluated based on the large inclusions evaluation method. Furthermore, it is an object of the third that eliminate the percentage loss products and short life products, to provide a rolling bearing which can achieve a long life of the entire bearing. In order to achieve the objectives of the first size large inclusions that were placed in an ultrasonic transmission medium ultrasonic probe and rod consisting evaluated bearing steel, present in the inspection volume of and to determine the number, to estimate the presence probability of large inclusions evaluated bearing steel. Also, by limiting the large inclusions present in the steel in the bearing based on the large inclusion evaluation method, to achieve the second object. Furthermore, in order to achieve the third object, a diameter of 180mm or less, the material of seamless steel pipe wall thickness of 25mm or less and a rolling bearing which is guaranteed to be free from defects of 1mm or more in length at the stage of the material to prepare.