Longitudinal Edge Cracks on Steel Plates After Hot Rolling

http://www.sciencedirect.com/science/article/pii/S092150930500448X

Yes, I know this article, but not enough to solve my problem,

In my workplace, hot rolled carbon steel plates are having side-cracks on edges large cracs ranging from very light to very deep in nature. I had done different trials for it but not so good result so i confused..

Scarfing, increas the furnace temperature, different turn strategies.. etc. but after all trial,

Double broadsiding (Slab edge= Plate edge) plates have this problem

What

If you don't find the answer in the rolling mill:

1. check cooling homogeneous conditions in the original material, I suppose is a continuous casting one.

2. Check temperature differences in the corresponding area at the same straw point.

3. Checkbubles in the corresponding near to surface line of the casted section

4. Check microestructure in thta area in the corresponding casted section

5. Finally, check again in the rolling mill for:

- strong cooling application in that area

- overlap of material in reducing thickness after edging (big edging) operations

Good luck

Thank you for opinion,

Rolling Trials,

deep cracks,

Rolling strategies two turn (Slab edge= Plate edge),(generally , cracks are showed under the plate side )

1- no use edger , side cracks is coming

2- slab sides sliding (50 mm each edge), side cracks is coming,

pusher type furnace is used

EH32,

lightly cracks,

1 turn, or no turn,

walking beam type furnace is used

skarfing the slab,

rerolled slab (Plate slab for thin plate)

About the reheating furnace, specially the pusher type one, please check if the distance between crack lines correspond to distances between skids inside the furnace (heating zone) or with the skids of the discharging system you use, ramp, fork,...

As soon as we saw side cracks under the plate , at first We focused the pusher type furnace , we checked under the send back slab, then skids marks, ramp, stopper etc. We tried fix furnace up those, Plate Mill was working on the walking beam furnace and the same problem comes up too.. side cracks is the same but effect is not , side cracks appearance's the same.

cracks view;

like a shell (width is 30-40 mm),

smooth scratch,grinding scratch, depth:0,2-1 mm,

Hot shortness? What is the Cu content?

Ron

I am not thinking about hot shortness, I understand we are talking about flat products with nor such kind of problems. Just temperature differences in short distances, sudden cooling, plus processing problems.

Thank you for interesting,

Grade:EH32 or A36 , no Cu,

Hot shortness?

Hot shortness?
Cu segregation.Ron

Hot shortness refers to shortness effect specially at the continuous casting due to high temperatures and high Cu concentrations, when solidifying. Segregation of Cu is not exactly the same and refers to segregation of Cu in the skin dendrite spaces when steel is maintained at high temperatures during long times. This is more typical of pusher furnaces where you can't put the charge out in breakdown times, etc, not typical of walking beam furnaces, moreover I can't find any reason why it would segregate in a line or ...

If the reasons pointed previously do not fit the problem, it could also be a problem of ingot slag passing getting sticked to the section. If cracks appear and disapear check the CC speeds when it appars and when it doesn't.