Slitting in hot rolled coils for steel pipe manufacturing

Symptoms

We are using hot rolled coils for steel pipe manufacturing. Hot rolled coils are slitted depending upon the pipe diameter and the helix angle calculation. We often encounter edge-like cracking up to 25 mm at slitted edges of hot rolled coils. Edge splitting of slitted coils was also observed.

The slitting problem was encountered in hot rolled coils when these are sent for slitting. Edge-like cracking was observed at slitted coils’ edges before welding.

Kindly advise what could be the real cause of edge splitting and what remedial measures can be taken?

Medicine

Normally hot roll product is very easy to slit, and results in very few difficulties, especially in regard to cracking.

The first thing to check would be the chemistry of the material itself.

Second, how has the material been cooled after being rolled from the steel mill?  The outside edges of course will be the first to be affected, and if too hard in Rockwell, they could be subjected to the cracking you are describing. 

Lastly, insure your set up is proper on the slitter.  Below, I have included some technical data from Cowles, a leading manufacturer of slitting knives and equipment.

I hope this information helps you determine your root cause of your cracking of the edges.