Hot-rolling & Cold-rolling

- Feb 14, 2019-

Hot-rolling & Cold-rolling

 

1. What is hot-rolling & cold-rolling?

 

Hot Rolling: Hot rolling is a kind of metalworking in comparison with cold rolling. When metal stock is processed through hot rollling, it is heated above its recrystallization temperature. In short, the process that the billets is heated and rolled a couple of times and cut into desirable shape and finally straightened out is called hot rolling.

 

Cold rolling: In cold rolling, the material is hot-rolled steel, which is going to be cold-rolled after pickling and getting rid of oxide. Finally the finished products is harden.

 

2. Comparison between advantages & disadvantages

 

Hot-rolling

Advantage: 

Hot rolling can destory the inside structure of ingots to subdivide it into grains and get rid of microstructural flaws. As a result, the structural thickness and mechanical properties are improved. This kind of change is found in the direction of rolling with isotropy. The bubbles, cracks and loose parts disappear under high temperature and prussure.

Disadvantage:

a. After hot-rolling, non-metallic inclusion(mainly sulfide and oxide) inside ingots become flakes layered inside, which reduces ingots’ tensile property in the direction of thickness and possibly tear ingots when weld joints shrink.

b. Nonuniform cooling causes residual stress. The structual steel of various cross-sections contains residual stress, which balances itself when there is no any external force and grows with larger cross-section. Despite its balance by itself, it can partly influence the structural properties when there is some external force, such as defromation, stability, etc.

 

Cold-rolling

Advantage: 

High speed to shape the stock, high production, no damages on coating, diverse cross-section to meet different needs. Cold-rolling can improve the yield point of the steel stock vis profound plastic deformation.

Disadvantage:

a. The residual stress is produced though without thermal plastical compression to influence the overall and partial buckling.

b. Cold-rolling section steel with open section is characterized by low free torsional rigidity.

c. Low concentrated load at place of joint is subjected to relatively small thickness.

 

After identification of the process, you have a preliminary sense to choose a proper lathe or a machine. 

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What next? ----A lathe can help you to turn your bar into desirable size and appearance.


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Finally, your bar is going tobe like this. Bright, shiny, smooth and attractive!


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Yantai Haige Machine Tools Co., Ltd. was built in 1999, which specializes in producing steel finishing equipment, such as hard chrome electroplating equipment, Series JY Bar Straightening Machine, Abrasive Belt Ginder, Drawing Machine, Shot Blasting Machine, Centerless Grinding Machine, CNC skiving and Roller Burnishing Machine and Auxiliary Machine etc. We also engage in continuous hard chrome plating equipment and heat treatment equipment.

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Click here to find more: 

http://www.steelfinishingline.com