Steel Bar (Rebar) Quality Problem

[mavericktim89]

Hi, I'm working in a Steel Bar Rolling Mill and we produce steel bars for construction. Lately I'm problems with the Yield Strength of the finished products. The YS has a very large difference between the head and tail of the product. I have tried a few things to arrest this problem:

1. Increase/maintain the pinching of the pinch roller and control it's speed
2. Adjusting the cooling box water flow rate and pressure
3. Maintaining a uniform bar diameter throughout the whole product (consistent tolerance)

However the problem still exists. What else I can think of is:

1. Raw material chemical composition problem
2. Under heat raw material in furnace

Has anyone had this problem before?

 

[weldstan]

Is rebar continuous cast? Do check chemistry of both ends regardless of ingot or cc.

 

[FennLane]

What kind of Rebar as this may have a bearing on the problems you are having.

Where do you buy our raw material and have you checked the stock you are using prior to rolling?

 

[Ron]

Most rebar mills are charged by varying scrap metal. This always creates quality issues in the final product. Consider adding some better quality scrap....a bit more actual steel rather than car bodies and refrigerators. This will involve the management in helping to induce more incentive to get better quality steel.