What is the difference between SUJ2 and SAE52100 bearing steel?
To put it simply, very little difference. They are both standards which are applied to the chemical composition of Chrome Steel (also known as Chromium Steel and High Carbon Chrome Steel). SUJ2 is a Japanese standard, whilst SAE52100 is a U.S. standard. Both of the above standards are exactly the same for 4 of the 7 major elements used in Chrome Steel. Of the remaining 3 elements the specifications overlap, meaning that an SUJ2 bearing steel is also in many cases conforming to SAE52100 and vice versa. That is not to say that all batches of one will also conform to the other, but the differences are minimal anyway. Don’t let anyone tell you that one is better than the other.
