Most hand saw blades are made of carbon tool steel, and most machine saw blades are made of "wind steel" (W18Cr4V, etc.). Carbon steel saw blades are cheap and have higher hardness and strength. Wind steel is low and not as durable as wind steel.
Saw blades are universal in most cases and there is no need to choose. But for materials with higher hardness, it is better to choose wind saw blades.
T7, T7A substantive analyte steel. It has good plasticity, toughness and strength, as well as a certain hardness, and can withstand vibration and impact loads, but has poor cutting ability. Used to manufacture tools that do not bear large impact loads and require appropriate hardness, wear resistance, and good toughness, such as forging dies, chisels, hammers, punches, metal shears, reamers, stamps, and woodworking tools , pneumatic tools, machine tool tips, bench tools, drilling tools, blunt surgical medical tools, etc.
T8, T8A *** analysis steel. It is easy to overheat during quenching and heating, deformation is large, plasticity and strength are relatively low, and it is not suitable to make tools that can withstand large impacts. However, it has higher hardness and wear resistance after heat treatment. Used to manufacture workpieces whose cutting edge does not heat up during operation, such as woodworking tools, pneumatic tools, bench tools, simple molds, rivet dies, center hole blunderbuss and dies, tools for cutting steel, bearings, knives, aluminum and tin Alloy die-casting plates and cores, as well as various springs, etc.
T8Mn, T8MnA chromium-deposited steel. It has high hardenability and hardness, but low plasticity and strength. Used to manufacture woodworking tools with larger cross-sections, hand saw blades, engraving tools, rivet dies, clockwork springs, band saw blades, disc saw blades, chisels for coal mines, chisels for masonry, etc.
T9, T9A electrolyzed steel. It has higher hardness, but lower plasticity and strength. Used to manufacture various tools that require higher hardness and a certain degree of toughness, such as engraving tools, rivet dies, press dies, punches, woodworking tools, machine cutting parts, rock drills and casting mold shunt nails wait.
T10, T10A electrochemically analyzed steel. The grains are fine and will not be overheated during quenching and heating (temperature reaches 800°C), and the fine grain structure can still be maintained; after quenching, there are undissolved excess carbides in the steel, so it has higher wear resistance than T8 and T8A steel. , but the toughness is low.
Used to make tools whose cutting edges do not heat up during operation, tools that do not bear impact loads but have sharp edges and a little toughness, such as tools for processing wood, hand cross saws, hand saws, etc. Joinery tools, machine joinery tools, machine joinery tools, twist drills, drawing dies, punch dies, cold heading dies, screw taps, reaming tools, thread rolling boards, turning tools, planers, milling cutters, currency stamps , small-size cold cutting edge and punching dies with uniform cross-sections, low-precision pallets with simple shapes, bench scrapers, hard rock drills, tools for making rivets and nails, screwdrivers, files, chisels for engraving, cutting paper and tobacco leaves Use knives, etc.
T11 and T11A are electrochemically analyzed steels. It has better comprehensive mechanical properties (such as hardness, wear resistance and toughness, etc.), finer grains, and is less sensitive to the formation of carbide networks when the grains grow when heated.
Used to make tools whose cutting edges do not heat up during work, such as saws, chisels, taps, files, scrapers, springs, gauges, reamers, dies, and tools for cutting tobacco leaves. , cold punching dies and woodworking tools that are small in size and have no sharp changes in cross-section
T12, T12A processed steel. Due to the high carbon content, there are still more excess carbides after quenching, so the hardness and wear resistance are high, but the toughness is low, and the quenching deformation is large. Not suitable for manufacturing tools with high cutting speed and impact loads. Used to manufacture tools that are not subject to impact load, cutting speed is not high, and the cutting edge does not heat up, such as turning tools, milling cutters, drills, reamers, reamers, taps, dies, scrapers, gauges, blades, small Punch, steel file, saw, spring, knives for cutting tobacco leaves, cold cutting edge dies and punching dies with small cross-section sizes, etc.
T13, T13A electrolyzed steel.
Due to the high carbon content, there are more excess carbides after quenching, so the hardness is higher and the toughness is worse; and due to the increased number and uneven distribution of carbides, the mechanical properties are poor. Not suitable for manufacturing cutting tools subject to shock loads and higher speeds.
Used to manufacture metal cutting tools that are not subject to impact loads but require extremely high hardness, such as razors, scrapers, drawing tools, files, engraving tools, drills, and tools for hard rock processing and Engraving tools, etc.
High-speed steel
1. Overview
High-speed steel is also known as wind steel or front steel, which means that it can harden even when cooled in the air during quenching, and Very sharp. It is an alloy steel with complex composition, containing carbide-forming elements such as tungsten, molybdenum, chromium, and vanadium. The total amount of alloying elements is about 10 to 25. It can still maintain high hardness under high heat generated by high-speed cutting (about 500°C), and the HRC can be above 60. This is the most important characteristic of high-speed steel - red hardness. After quenching and low-temperature tempering, carbon tool steel has a very high hardness at room temperature, but when the temperature is higher than 200°C, the hardness drops sharply. At 500°C, the hardness has dropped to a level similar to the annealed state. , completely losing the ability to cut metal, which limits the use of carbon tool steel in making cutting tools. Due to its good red hardness, high-speed steel makes up for the fatal shortcomings of carbon tool steel and can be used to make cutting tools.
The heat treatment process of high-speed steel is relatively complex and must go through a series of processes such as annealing, quenching, and tempering. The purpose of annealing is to eliminate stress, reduce hardness, make the microstructure uniform and facilitate quenching. The annealing temperature is generally 860~880℃. Quenching is generally performed in two stages due to its poor thermal conductivity. First preheat at 800~850℃ (to avoid causing large thermal stress), then quickly heat to the quenching temperature of 1220~1250℃, and then oil cool. The factories all use salt furnaces for heating. After quenching, some (about 30%) retained austenite remains in the internal structure and has not been transformed into martensite, which affects the performance of high-speed steel. In order to transform the retained austenite and further improve the hardness and wear resistance, tempering is generally performed 2 to 3 times at a tempering temperature of 560°C and heat preservation for 1 hour each time.
(1) Manufacturing method: Usually electric furnace is used for production. Recently, powder metallurgy method has been used to produce high-speed steel, so that carbide particles are evenly distributed on the matrix in the form of extremely fine particles, which improves the service life.
(2)Usage: used to manufacture various cutting tools. Such as turning tools, cobalt heads, hobs, machine saw blades and demanding molds, etc.
2. Main manufacturers
my country's Dalian Steel Plant, Chongqing Steel Plant, and Shanghai Steel Plant are the main manufacturers that produce high-speed steel.
3. Main import producing countries
my country mainly imports from Japan, Russia, Germany, Brazil and other countries