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The Differences between Bainitic, Pearlitic and Acicular Rollers


The Differences between Bainitic, Pearlitic and Acicular Rollers

Bainitic Rollers:
Bainitic rollers have good wear resistance and toughness, and can effectively resist the wear caused by rolled materials and withstand large impacts and alternating loads. The bainite in its structure can provide higher hardness and strength while maintaining a certain toughness. Widely used in the work rolls of hot rolled strip mills, it can ensure the surface quality and dimensional accuracy of the strip. Its microstructure makes the surface of the roll have less wear during long-term rolling, which can effectively extend the service life of the roll, reduce the replacement frequency and improve production efficiency.

Advantages:
The service lifespan of bainitic roller is relatively long because roll has the charateristic of excellent hardness and wear-resistance, the product efficiency is improved for reducing the frequency of roll replacement.
It can work stably under harsh rolling conditions such as high temperature, high pressure and high wear.
Disadvantages:
Complex manufacturing process: The production process has high requirements, resulting in relatively high costs.
Strict requirements for heat treatment: Precise control of heat treatment process parameters is required to obtain the ideal bainite structure.
Application:
Widely used in work rolls of hot rolled strip mills and other parts with high requirements for roll performance.

 

Pearlitic Rollers:
The strength and hardness of pearlitic rollers are relatively low, but the balance of wear resistance and toughness is better. It is often used in some occasions where the requirements for roll performance are not particularly strict. For example, pearlitic rollers can be used in the roughing or intermediate rolls of some small and medium-sized rolling mills.

Performance characteristics:
Hardness: The hardness is relatively moderate and can withstand the pressure and wear during the rolling process to a certain extent.
Wear resistance: It has certain wear resistance, but its wear resistance is usually not as good as that of bainitic or acicular ferrite rollers.
Toughness: It has good toughness and is not prone to brittle fracture when subjected to impact and alternating loads.
Advantages:
Low cost: The manufacturing process is relatively simple, and the cost of raw materials is relatively low, so the price is more economical.
Good thermal stability: It can maintain relatively stable performance within a certain temperature range.
Disadvantages:
Limited wear resistance: For some rolling conditions with high strength and high wear, it may not meet the requirements for long-term use.
Small space for hardness improvement: It is difficult to significantly increase its hardness through further processing.

 

Acicular Rollers:
Acicular ferrite rollers have excellent toughness and fatigue resistance and are often used in high-strength and high-load rolling conditions.
The wear resistance and toughness of acicular ferrite rollers are mainly as follow:


Wear resistance:
The fine and uniformly distributed microstructure of acicular ferrite can effectively withstand wearings. For example, during high-intensity rolling, its fine structure can reduce micro-wear and spalling on the surface.
Usually it has a higher hardness, which enables it to withstand the friction and wear with the rolled material and slow down the wear rate of the roll surface.
Good anti-fatigue performance means that during long-term and repeated rolling, it is not easy to cause cracks and aggravated wear due to fatigue.


Toughness:
The crystal structure characteristics of acicular ferrite give the roll good toughness and can absorb and disperse the impact energy during the rolling process. For example, when encountering sudden overload or impact, brittle fracture is not easy to occur.
The structure formed during the phase transformation can improve the toughness of the material and make it have better anti-fracture ability under complex rolling conditions.
The acicular ferrite structure can hinder the propagation of cracks. Once micro-cracks appear, they are not easy to rapidly develop into large cracks and cause roll failure.
In general, the synergy of wear resistance and toughness of acicular ferrite rollers enables them to maintain good working performance and a long service life under harsh rolling conditions.

 


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