Full Analysis of Hot Rolling Roll Materials: Each Roll Costs Hundreds of Thousands, Choosing the Wrong Material Results in Direct Scrap

Those familiar with dry rolling steel know that the roll is the “heart” of the entire production line – and also the most costly consumable.

Each roll costs tens of thousands or even hundreds of thousands of yuan. Choosing the right material ensures a long rolling cycle, good surface quality, and fewer roll replacements; choosing the wrong material leads to roll breakage, breakage, and rough surfaces, causing production to stop in no time.
But there are so many types of roll materials: forged steel, cast steel, semi-steel, high-chromium cast iron, high-speed steel, infinitely hardening… Which material should be used in which position?

Today, combined with an “internal comparison table of hot rolling roll materials” in the industry, we will explain this matter thoroughly.

The Entire Hot Rolling Process, Different Roll Materials for Different Machines

The hot rolling production line, from roughing to finished products, each rolling machine has different working conditions, and therefore the roll materials are also different.

It’s not that the more expensive, the better. What matters is the suitability.

Hot Rolling Roll Material Comparison Table

Do you understand? The closer to the rear of the finishing rolling stands, the higher the material grade and the more expensive the price.
Why? Because

Finishing rolling: High temperature, large reduction ratio, the key is to be “robust”, not easy to break or crack.

Finishing rolling: Focus on surface quality and the number of rolling kilometers. The key is “wear resistance + smoothness”. The material must be upgraded.

Now let’s talk about the key points.

Finishing rolling section: Resisting impact is the top priority

Shearing machine/initial rolling: Mainly forged steel, resistance to impact is the first priority

The shearing machine is the “first step” of the entire line – when the steel ingot comes out of the heating furnace, the temperature is high, the cross-section is large, and the reduction is severe.
What is the most feared at this time? Breakage of the rolls.

So the material must use steel with high strength and good toughness, such as 60CrMnMo forged steel. The characteristics of forged steel rolls are:

• Internal structure is dense, high strength
• Good toughness, strong resistance to impact
• Not prone to breakage, but the wear resistance is average

“Before the first two rolls of finishing rolling, we don’t care about high wear resistance, but first ensure no breakage. Once a roll breaks, the entire line will stop for half a day, and the money lost is enough to buy several rolls.”

The finishing rolling section after R3 and R4: Semi-steel, high-chromium cast steel come into play

At R3 and R4 and later sections of finishing rolling, the working conditions change – the reduction is not so large, but the problems of wear and thermal cracking start to stand out.

At this time, semi-steel and high-chromium cast steel are commonly used:

Semi-steel has a carbon content of about 1.5% to 2.0%, its structure is between steel and cast iron, having both the toughness of steel and the wear resistance of cast iron. It belongs to an “all-purpose” material, with high cost performance.

High-chromium cast steel has a higher chromium content (usually 2.8% to 3.4%), with a large amount of chromium carbides, and its wear resistance is much higher than ordinary cast steel. But its toughness is slightly worse, and it cannot be used in positions with too much impact.

Finishing rolling section: It’s all about wear resistance and surface quality

F1-F3: Medium-chromium/high-chromium cast iron + semi-high-speed steel

At the first few rolls of finishing rolling, the steel plate is already relatively thin, and surface quality becomes important.

At this time, the main force is high-chromium cast iron rolls -High-chromium cast iron contains a large amount of chromium (12% to 18%), which combines with carbon to form hard and wear-resistant chromium carbides (Cr7C3). These hard particles are like pebbles on a gravel road, with a wear resistance several times higher than ordinary steel.

There is also a tough character: semi-high-speed steel.

The carbon and alloy content of semi-high-speed steel is between high-chromium cast iron and high-speed steel, having good wear resistance and good heat resistance. Used in the front section of finishing rolling, it can withstand the temperature and still ensure a certain surface quality.

F4-F7 finished product section: High-speed steel HSS is the king

At the finished product section, the surface quality is the key.
At this time, the rolls require the highest standards:

• Super wear resistance: Long rolling cycle, fewer roll replacements, high output
• Smooth surface: No spots, no chips, otherwise the surface will leave marks
• Good heat stability: Hardness does not decrease much at high temperatures

High-speed steel HSS (High Speed Steel) is the one to do this.

High-speed steel rolls have a large amount of alloy elements such as tungsten, molybdenum, vanadium, and chromium, forming various types of carbides, with particularly good high-temperature hardness (red hardness). Other materials become soft at the rolling temperature, but high-speed steel can still maintain high hardness.

“Finished product rolls use high-speed steel rolls, and the rolling kilometers of semi-steel can be several times that of high-chromium cast iron. Although a roll is more expensive, when calculated per ton of steel, it is actually more cost-effective.”

Supporting rolls: The “behind-the-scenes heroes” who remain unnoticed

The working rolls “charge forward” in the front, and there is a thicker and larger supporting roll in the back that is silently carrying the load.

The supporting rolls do not directly contact the steel plate, but their role is crucial – providing rigid support for the working rolls to prevent them from bending and deforming.
The material of the supporting rolls is usually 70CrNiMo forged steel, with the following characteristics:

• High strength: Can withstand huge rolling forces
• Deep quenching: High surface hardness, wear resistance, and deep hardened layer
• Good toughness in the core: Not prone to roll breakage

The supporting rollers are large in size and expensive, often costing several hundred thousand yuan each. They have a long lifespan, but once they malfunction, the losses will be significant.

“Typical Failures” of Common Materials, Know Them in Advance

When choosing materials, not only should you consider their performance, but you also need to know what problems each material is most prone to, so you can have a clear idea.
In brief:

Stainless steel rolls are most prone to breakage and cracking – high in strength but not hard enough, and they wear out quickly.

Cast iron rolls are most vulnerable to chunks falling off and peeling – hard but brittle, and they may break under high impact.

High-speed steel rolls have the best comprehensive performance, but they are also the most expensive, and they require high standards for use and maintenance.

What Can CYKC Do for You When Selecting Rolling Rods

Having talked about the materials, let’s come back to what we can do for you.
CYKC Group is a professional rolling rod manufacturer and exporter for the global steel industry. Our products cover:

• High-speed steel rolling rods (HSS Rolls).
• Infinite cold-hard cast iron rolling rods (ICDP Rolls).
• Half-steel rolling rods (Adamite Rolls).
• Tungsten carbide rolling rods.
• Hard alloy roller rings.
• And other types of rolling rods.

Our high-speed steel rolling rods have a steel production capacity that can reach 3-5 times that of ordinary rolling rods, which can significantly shorten the rolling rod replacement cycle, reduce rolling rod consumption, and improve the operation efficiency of the rolling mill.
Our services:

You only need to provide the product drawings. From placing the order, designing, shipping to after-sales, we take care of every step.

Not sure which type or specification of rod to choose? Send us the drawings, dimensions, steel type or operating conditions, and our engineers will recommend a suitable solution.

Global distribution support is provided, including sea freight, air freight, and land transportation, depending on the requirements.

Pre-sales professional technical guidance is provided. Welcome to visit our factory on-site.
After-sales on-site installation, commissioning and maintenance services are provided, with full quality tracking.

Our products have been exported to more than 100 countries in Europe, Asia, Africa and America, focusing on high quality and long service life, helping customers reduce costs and improve efficiency.

One last thing to say

Rolling rods may all look like “iron lumps”, but there are deep secrets inside.

Choosing the right material can achieve twice the result with half the effort; choosing the wrong material can achieve twice the effort with half the result, or even result in scrap.

When selecting rolling rods, it is not necessary to choose the most expensive ones. The one that suits your working conditions and products is the best.

CYKC Group – Rolling rods, roller rings and various steel rolling accessories. You provide the drawings， we do the work, clear and transparent.

E-mail: cykc@cykcgroup.com.cn