1. Brief introduction
Wear resistant steel plate refers to a special plate product specially designed for use under conditions of extensive wear. At present, commonly used wear resistant steel plates are made by welding a certain thickness of alloy wear resistant layer with high hardness and excellent wear resistance on the surface of ordinary low-carbon steel or low-alloy steel with good toughness and plasticity.In addition, there are cast wear-resistant steel plates and alloy quenched wear-resistant steel plates.
Wear resistant steel plate consists of two parts: low carbon steel plate and alloy wear resistant layer. The alloy wear-resistant layer is usually 1/3 to 1/2 of the total thickness.During operation, the matrix provides comprehensive properties such as strength, toughness and plasticity to resist external forces, while the wear-resistant alloy layer provides wear resistance that meets the specified working conditions. The thickness of the wear-resistant alloy layer is 3-20 mm.
There are two popular types of wear-resistant steel plates on the market, one is wear-resistant composite steel plate, and the other is NM wear-resistant steel plate. Typical examples include NM360 wear-resistant plate, NM400 wear-resistant plate, NM500 wear-resistant plate, etc.
Wear resistant steel plates are also known as quenched and tempered steel plates after quenching and hardening during the rolling process or after heat treatment quenching and hardening of low-alloy steel plates. The hardness is generally between HB350-500.
2. Advantages and Features
Impact resistance
The impact resistance of wear-resistant plates is very good. Even if there is a very high drop during the transportation of materials, it will not cause too much damage to the wear-resistant plates.
Heat resistance
Generally, wear-resistant plates below 600 degrees can be used normally, but if we add some vanadium and platinum when making wear-resistant plates, then high temperatures below 800 degrees are not a problem.
Corrosion resistance
Due to the high content of chromium in the wear-resistant plate, the corrosion resistance of the grinding plate is excellent, and there is no need to worry about corrosion or other issues.
Cost effectiveness
The price of wear-resistant plates is 1-2 times that of ordinary steel plates, but the service life of wear-resistant plates is more than 10 times longer than that of ordinary steel plates, so their cost-effectiveness is relatively high.
Easy to process
The weldability of the wear-resistant plate is very strong, and it can also be easily bent into various shapes, making it very convenient to process.
3. Characteristics
Mechanical property
NM360: Hardness of 330-390HBW, yield strength ≥ 900MPa, tensile strength ≥ 1100;
NM400: Hardness of 370-430HBW, yield strength ≥ 1000MPa, tensile strength ≥ 1200;
NM450: Hardness of 420-480HBW, yield strength ≥ 1100MPa, tensile strength ≥ 1250;
NM500: Hardness of 470HBW or above, yield strength ≥ 1200MPa, tensile strength ≥ 1500.
chemical composition
The chemical elements commonly contained in wear-resistant steel include silicon, manganese, chromium, molybdenum, vanadium, tungsten, nickel, titanium, boron, copper, rare earths, etc
4. The difference between ordinary wear-resistant steel plate and composite wear-resistant plate
(1) Definition
Wear resistant composite steel plate refers to the composite of high alloy wear-resistant layer on the substrate of ordinary steel plate by welding method, combining the wear resistance of the wear-resistant layer with the bearing, deformation and weldability of the substrate. The hardness of the wear-resistant layer is generally between HRC52-64.
NM wear-resistant steel plate refers to the steel plate that is quenched and hardened during the rolling process of low-alloy steel plate or after heat treatment quenching and hardening of low-alloy steel plate, also known as quenched and tempered steel plate. The hardness is generally between HB350-500.
(2) Wear resistance performance
The wear-resistant layer of wear-resistant composite steel plate is composed of high alloy components, and there are a large number of high hardness alloy carbides (around HV1600) embedded in the matrix in the metallographic structure, which are the main carbides that play a role in wear resistance. The actual micro hardness of the wear-resistant layer is much higher than the measured macro hardness. Its strengthening method is the same as that of hard alloy. NM wear-resistant steel plate is quenched and hardened as a whole, and the presence of martensite in the metallographic structure increases the overall hardness. The micro hardness and macro hardness are basically the same. We are familiar with the two materials used for cutting tools: hard alloy and T10. Even if the macroscopic hardness of quenched T12 steel and hard alloy is basically the same, the wear resistance of hard alloy is much higher than that of T12 steel. The reason is that there are a large number of carbides in hard alloy, so the wear resistance of wear-resistant composite steel plate is better than that of NM wear-resistant steel plate.
(3) Temperature resistance performance
NM wear-resistant steel plates gradually lose their hardness after annealing above 250 , resulting in a significant decrease in wear resistance. The welding process can also cause a decrease in hardness near the weld seam; The wear-resistant layer of wear-resistant composite steel plate is composed of high alloy and has a secondary hardening effect at a certain temperature. It can generally work below 650 .
(4) Drilling method
NM wear-resistant steel plates can be drilled using mechanical methods, and high-speed alloy steel (HSS-E) or cobalt containing high-speed alloy steel (HSS-Co) drill bits are recommended for drilling wear-resistant steel plates; Wear resistant composite steel plates cannot be drilled by mechanical methods, only plasma cutting and gas cannon step drilling can be used.
5. Application Industry
Wear resistant steel is widely used in mining machinery, coal mining and transportation, engineering machinery, agricultural machinery, building materials, power machinery, railway transportation and other sectors. For example, steel balls and lining plates for ball mills, bucket teeth and buckets for excavators, rolling bowl walls, gear plates, and hammer heads for various crushers, track plates for tractors and tanks, striking plates for fan mills, railway turnouts, middle groove plates, groove ribs, and circular chains for coal mine scraper conveyors, shovel blades and teeth for bulldozers, lining plates for large electric wheel truck buckets, roller drill bits for oil and open-pit iron mine perforation, and so on
6. Processing method
(1) The steel plate cutting method is suitable for both cold cutting and hot cutting. Cold cutting includes water jet cutting, shearing, sawing or abrasive cutting; Thermal cutting includes oxygen fuel flame cutting (hereinafter referred to as "flame cutting"), equal particle cutting and laser cutting.
(2) Cutting method: Through relevant process experiments, master the general characteristics and cutting thickness range of various cutting methods for steel plates.
(3) The flame cutting method for high-grade wear-resistant steel is as simple as cutting ordinary low-carbon and low-alloy steel. When cutting thick wear-resistant steel plates, attention should be paid!!! As the thickness and hardness of the steel plate increase, the tendency for cracks to appear at the cutting edge increases.
(4) Elimination of cutting edge cracks:
The best method to eliminate edge cracks is to preheat before cutting. Before flame cutting, preheating is usually required.
Preheating can be achieved through oxygen flame combustion guns, electronic heating pads, or heating furnaces. The required temperature should be measured on the back of the heating pad.
The entire steel plate section should be uniformly heated to prevent local overheating in the area in contact with the heat source.
The preheating temperature depends on the grade and thickness of the steel plate.
Conclusion
With the rapid development of the manufacturing industry, the demand for advanced wear-resistant steel is gradually increasing. The research and production of high value-added advanced wear-resistant steel is of great significance to the development of the entire industry. Feedback from our users - The use of Liangang NM series quenched and tempered wear-resistant steel plates to process the wear-resistant lining plates of dock unloaders has greatly improved the service life of the wear-resistant lining plates, reduced the frequency of wear-resistant lining plate replacement, and greatly improved work efficiency
