Surface Defect Levels in Hot Rolled Steel

[jimsan]

What is the "permissable" surface defect level in hot-rolled steel bar/billet (e.g 80mm round cornered square) which would be supplied as "suitable for upset forging"?

I understand there is an acceptable level even though , after hot forging, the defect will be transferred into the forged part.

JimSan

 

[BillPSU]

No matter if there is a standard or not for "permissable" defect the final agreement on what is permissable or not is decided between the the customer and supplier.

There are plate flatness spec's which were written many years ago. Many suppliers quote half tolerance on the flatness spec on their materials. Some suppliers give one fourth of the published spec as their flatness tolerance. What drove this tighter flatness tolerance? Customers.

Acceptable or permissable surface defects should be viewed as what does the customer need to make a good product. Agreeement must be met on both sides.

 

[MOB1]

When I worked in a steel works some years ago there were suffixes after the steel grade designation which set the surface defect limits for steel suitable for drop forging, spring manufacture etc.
There were no standards quoting these values as they depended on the section size and how much "reconditioning" the steel works carried out before and after rolling bars.