Metallurgy Basic Doubts

Hi Guys,

I have few doubts regarding Metallurgy.

We are using Bearing Steel (EN-31 / SAE 52100) for manufacturing certain components. We are using commercial quality material from ISMT and other suppliers to manufacture the same. We get tubes from ISMT while rounds from other suppliers. Rounds are then forged and used to make the finish components while the tubes are cut into short pieces and then used to make the finish components.

After machining all the components are heat treated to achieve surface hardness of about 61 HRC and more. Then they are polished and sold off.

My doubts are:

1) Is it better use a Tube from ISMT or Forged pcs made of commercial quality bearing steel from non-standard suppliers?

2) What is the difference between Prime Quality Steel & Commercial Quality Steel? How can I check it? Is there any difference between forged pcs of both quality? (Is the difference in quality still intact after getting forged?)

3) Is there a process that can help these components get better life?

4) I've heard that when bearings are made from forged steel 3mm from OD, ID & Width are removed. If I am not wrong its to remove some carbon. Please elaborate about this. I am not manufacturing bearings but do I need to remove 3mm material too, to get better life or other qualities.

I have other questions as well but shall post them in a day or two. In the mean while please help me out here.