Thermal stress fracture of work rolls during steel rolling process

^Breakage part of work roll: roll barrel

 ^How it looks like?

-Normally occurs in roughing stands. Generally speaking, breakage happens after less than 10 pcs of steel rolling from beginning of work roll change, and more likely to happen in winter.

 -Fracture surface shows a radial direction from hub to barrel surface.

 $See pic as below:

^Why this happened?

-Caused by Max temperature difference between barrel surface and hub. Over-high temperature difference normally caused by temperature of barrel surface climbing up too fast, due to lack of cooling water during the steel rolling process.

We Kaida Roll suggest:

-Roll pre-heating, particularly in winter, meaning work rolls shouldn’t be colder than room temperature,

 -small output at the begging of rolling process, then gradually increasing rolling steel output until reach a stable temperature difference of the barrel cross section. 

 -Keep adequate cooling water