CN106929770A - A kind of roll of boron high-speed steel containing aluminium - Google Patents

Abstract

A high-speed steel roll containing aluminum and boron belongs to the technical field of metal materials. Using electric furnace smelting, the chemical composition and mass fraction of aluminum-boron high-speed steel molten steel are 1.67～1.92C, 1.13～1.36B, 1.05～1.28Al, 5.04～5.37Cr, 2.17～2.55Mo, 0.78～0.99Si, 0.67 ～0.94Mn, 1.14～1.36V, <0.030S, <0.032P, the balance Fe, when the temperature of the molten steel reaches 1623～1648℃, the molten steel is taken out of the furnace to the ladle, and the bottom of the ladle is pre-added with an amorphous and nanocrystalline modifier. When the temperature of the molten steel drops to 1483-1526°C, the molten steel is poured into the mold to obtain an aluminum-boron high-speed steel roll blank. After machining and heat treatment, the roll has excellent performance.

Description

A kind of aluminum-boron high-speed steel roll

technical field

The invention discloses a high-speed steel roll, in particular to an aluminum-boron high-speed steel roll, which belongs to the technical field of metal materials.

Background technique

The development and application of high-speed steel rolls is a great change in the history of roll manufacturing technology. Compared with traditional roll materials, high-speed steel rolls have the characteristics of high hardness, good hardenability and good wear resistance. In order to improve high-speed steel rolls Chinese invention patent CN 106435370 discloses a special high-speed steel roll for cold-rolling high-strength automobile sheets. Its chemical composition and weight percentage are as follows: carbon 0.80-0.90%; silicon 0.20-0.45%; ～3.70%; Molybdenum 4.25～4.40%; Vanadium 1.50～1.70%; Tungsten 5.30～5.45%; Phosphorus≤0.030%; Sulfur≤0.030%; The manufacturing method of the special high-speed steel roll for cold-rolled high-strength automobile plate includes smelting and forging the roll billet according to the chemical composition and weight percentage, preliminary heat treatment and final heat treatment; the final heat treatment includes sub-temperature quenching + oil cooling and two secondary tempering treatment. The overall hardness of the improved high-speed steel roll is ≥64HRC, and has high wear resistance and good accident resistance, which can meet the rolling conditions of high-strength steel and ultra-high-strength steel. Chinese invention patent CN 104353798 also discloses a method for manufacturing high-speed steel work rolls used in the post-finishing section of hot continuous rolling. The chemical composition of the working layer of the roll body and the weight percentage of each composition are: C2.00-3.50 %, Si0.40～2.00%, Mn0.50～1.20%, Cr1.50～4.50%, Ni2.00～5.00%, Mo+V+W+Nb2.00～10.00%, S≤0.05%, P≤ 0.10%, the rest is Fe and unavoidable impurities. The manufacturing method includes steps of smelting, inoculation and spheroidization, pouring, and heat treatment. The invention obtains special graphite and metallographic structure by designing reasonable alloy composition and production process. The high-carbon high-speed steel rolls in the post-finishing section of hot continuous rolling can effectively control the surface quality of the rolls after they are off the machine, and at the same time improve the wear resistance and thermal cracking resistance of the rolls. Chinese invention patent CN106282821 also discloses a manufacturing method of a graphite-containing high-speed steel centrifugal composite steel core roll. In this invention, B and N chemical elements are introduced into the traditional high-speed steel components, and the matrix structure of the working layer is dispersed with a total area of Percentage 20-35% MC type and/or M ₂ C type, point and/or massive high-hard alloy carbides, nitrides, borides. The chemical composition of the working layer of the roll includes: C2.0-3.0%, Si0.8-2.5%, Mn0.2-1.0%, P≤0.05%, S≤0.02%, Cr3-10%, Ni0 .5-3.5%, Mo2.5-6.0%, V3-8%, W0-10%, B0-0.5%, N60-500PPM; and the working layer contains an equivalent spherical diameter of 20-50μm, and an area percentage of 0.5-1.5 % of point and spherical graphite; at the same time, 20-35% of the total area of MC type and/or M2C type, point and/or massive high-hard alloy carbides and nitrides are dispersed in the matrix structure of the working layer , boride; between the outer layer and the roll shaft also includes an intermediate layer; the graphite-containing high-speed steel centrifugal composite steel core roll is prepared by dynamic centrifugal casting the outer cylinder, the intermediate layer, and the static and upper and lower rolls The box combination of the neck part, when the outer cylinder and the middle layer are in a high-temperature solid state, pour high-temperature liquid core metal liquid, thereby realizing centrifugal composite casting molding; the step of preparing the outer cylinder by dynamic centrifugal casting Including charge preparation, smelting, carbon, nitrogen and boride modification treatment, graphite modification inoculation treatment, ladle pouring, cylinder solidification and graphite precipitation; During the process, the addition of particle modifiers promotes liquid Cr, Mo, V, W and other alloying elements to form tiny, dispersed suspended particles of high-melting carbides, nitrides, and borides in the form of high-temperature solids and precipitates out; the graphite metamorphic inoculation treatment It is based on carbon, nitrogen, and boride modification treatment by adding granular modifiers, so that the remaining carbon in the dissolved state in the molten metal will be precipitated in the form of tiny dots to form graphite in the subsequent pouring and solidification stage. In addition to retaining the unique high-temperature and anti-wear advantages of traditional high-speed steel rolls, the high-speed steel rolls also solve the problem of large friction coefficients of traditional high-speed steel rolls, give full play to the wear resistance of high-speed steel, and play a role in rolling. The lubrication between workpieces prevents the occurrence of steel sticking; and the thermal conductivity and lubricating properties of graphite can improve the disadvantages of high-speed steel rolls on thermal shock, thermal cracking sensitivity, easy sticking to steel, and easy surface roughening, especially in When the finished frame is used, the surface brightness of the rolled material is significantly improved.

Chinese invention patent CN 106216405 also discloses a nitriding high-speed steel roll suitable for bar cutting racks and its manufacturing method, which belongs to the technical field of roll manufacturing, including a roll neck and a working layer, a transition layer, and a core. The alloy composition and weight percentage of the roller body and working layer are: 1.2~2.2 carbon, 7.0~13.5 chromium, 0.2~1.2 nickel, 0.5~1.5 molybdenum, 1.0~2.5 vanadium, 1.0~2.5 tungsten, 1.0~3.0 niobium, 0.05~ 0.1 rare earth, phosphorus ≤ 0.04, sulfur ≤ 0.04, manganese ≤ 0.5, 0.6 ~ 1.5 silicon, the rest is iron; the matrix strength of the working layer is ≥ 600MPa, and the tensile strength of the working layer is ≥ 800MPa. This invention improves the matrix strength of high-speed steel rolls, Refine the grain, overcome the rolling environment of the split stand of the bar mill, and adapt to the rolling requirements of the split stand. Chinese invention patent CN 104525889 also discloses a method for manufacturing high-speed steel rolls suitable for small steel mills and wire and bar mills. The manufacturing method includes three process steps of smelting raw materials, pouring molding, mechanical processing and heat treatment; on the basis of centrifugal casting of high-speed molten steel, the transition layer of molten iron is first poured, and then the transition layer of molten iron is realized by pouring core molten iron. Complete replacement. This invention significantly improves the bonding strength between the outer high-speed steel and the core molten iron, and the bonding strength is increased from about 350Mpa to more than 500Mpa, which greatly improves the peeling resistance of the bonding layer of the high-speed steel roll body; at the same time, it can effectively remove the core molten iron The amount of carbide-forming elements in the outer layer is dissolved, thereby improving the structure of the roll neck, increasing the tensile strength of the roll neck, and effectively eliminating the phenomenon of roll breakage during use.

Chinese invention patent CN 105779861 also discloses a wear-resistant high-vanadium-nitrogen high-speed steel roll and its manufacturing method. The set is made of M2 high-speed steel (also known as W6Mo5Cr4V2 high-speed steel) scrap with a mass fraction of 20-24%, 4.5-4.8% vanadium-nitrogen alloy, 1.8-2.2% ferroniobium, 55-59% Q235 scrap steel, 10-12% Carbon ferrochromium, 1.2-1.4% electrolytic nickel, 0.30-0.45% titanium ferro and 1.2-1.4% metal aluminum ingredients are smelted in an electric furnace and cast into a roll sleeve on a centrifuge. After annealing, rough processing, After quenching, tempering and finishing treatment, it is combined with medium-carbon steel roll shaft by shrink-fitting, and it is used in section steel rolling mill, which has excellent wear resistance. Chinese invention patent CN 105618715 also discloses a wear-resistant high-speed steel composite roll and its preparation method. The composite roll is made of high-speed steel for the roll body and ductile iron for the roll core through centrifugal composite casting. The chemical composition and mass fraction of the molten steel for the roll body Controlled at 1.5-2.4%C, 3.5-6.0%Cr, 3.5-6.0%Mo, 3.5-6.0%V, 1.5-3.5%W, 0.6-1.2%Nb, 0.5-1.2%Ni, 0.3-0.8%Si, 0.3-0.8% Mn, S &lt; 0.04%, P &lt; 0.04%, the balance of Fe, deoxidize the molten steel of the roll body and use multi-element micro-alloy wire to modify the molten steel outside the furnace, and then cast it on the centrifuge The roller and the roller core are made of nodular cast iron, and the roller is tempered after quenching. It has the characteristics of high hardness, toughness and wear resistance, and has excellent use effect.

However, the above-mentioned high-speed steel rolls generally have the disadvantages of high addition of precious alloys and high production costs of the rolls.

Contents of the invention

The purpose of the present invention is to use aluminum into high-speed steel to greatly improve the high-temperature hardness and red hardness of the high-speed steel substrate, and to form high-hardness M ₂ B phases with boron and Fe, Cr, Mo and other elements in high-speed steel, greatly improving High-speed steel hardness, successfully developed a high-speed steel roll containing aluminum and boron.

An aluminum-boron high-speed steel roll is smelted in an electric furnace, and the specific preparation process steps are:

1) Melting aluminum-boron high-speed steel in an induction furnace first, the chemical composition and mass fraction of aluminum-boron high-speed steel molten steel are 1.67～1.92C, 1.13～1.36B, 1.05～1.28Al, 5.04～5.37Cr, 2.17 ～2.55Mo, 0.78～0.99Si, 0.67～0.94Mn, 1.14～1.36V, <0.030S, <0.032P, balance Fe; An amorphous and nanocrystalline modifier with a thickness of 0.15 to 0.80 mm is added, and the chemical composition and mass fraction of the amorphous and nanocrystalline modifier are 20.34 to 21.60% B, 1.23 to 1.44% Rb, 21.47 to 21.69% Al, and 3.66 to 4.01 %Ti, 0.91～1.08%C, 5.21～5.56%Ca, the balance is Fe and unavoidable impurity elements; the addition of amorphous and nanocrystalline modifier accounts for 0.63～0.87% of the mass fraction of molten steel entering the ladle, when the molten steel temperature When the temperature is lowered to 1483-1526°C, the molten steel is poured into the mold to obtain the aluminum-boron high-speed steel roll blank;

2) After rough processing, the aluminum-boron high-speed steel roll blank is heated in the furnace to 1055-1080°C, and after 2-4 hours of heat preservation, it is rapidly cooled at a rate of 18-22°C/min until the temperature is lower than 250°C, and then put into Heating the furnace to 500-540°C, keeping it warm for 12-15 hours, cooling with the furnace until the temperature is lower than 160°C, taking it out of the furnace and air-cooling to room temperature, and finally finishing to the specified size and precision to obtain the aluminum-boron high-speed steel roll.

In the invention, cheap aluminum and boron are used as main alloying elements to replace expensive cobalt, tungsten, niobium and other elements in high-speed steel rolls, so as to reduce the manufacturing cost of the rolls. In addition, the present invention first melts aluminum-boron high-speed steel in an induction furnace, and the process is simple. The chemical composition and mass fraction of the aluminum-boron high-speed steel molten steel are 1.67-1.92C, 1.13-1.36B, 1.05-1.28Al, 5.04 ～5.37Cr, 2.17～2.55Mo, 0.78～0.99Si, 0.67～0.94Mn, 1.14～1.36V, <0.030S, <0.032P, balance Fe. The addition of 1.67-1.92% C, 1.13-1.36% B, is to take into account the appropriate amount of wear-resistant carbides and wear-resistant borides, adding 1.05-1.28% Al can greatly improve the temper softening resistance of the roll material, and improve Roll oxidation resistance. In addition, adding 5.04-5.37% Cr, 2.17-2.55% Mo and 1.14-1.36% V is to obtain alloy carbides with high hardness and improve the wear resistance of rolls. On this basis, 0.78-0.99% Si and 0.67-0.94% Mn are added, mainly for deoxidation and strengthening of the roll matrix.

In the present invention, when the temperature of the molten steel reaches 1623-1648°C, the molten steel is taken out of the furnace into the ladle, and an amorphous and nanocrystalline modifier with a thickness of 0.15 to 0.80 mm is preliminarily added to the bottom of the ladle. The chemical composition and mass fraction of the amorphous and nanocrystalline modifier are: 20.34～21.60%B, 1.23～1.44%Rb, 21.47～21.69%Al, 3.66～4.01%Ti, 0.91～1.08%C, 5.21～5.56%Ca, the balance is Fe and unavoidable impurity elements, amorphous nano The amount of crystal modifier added accounts for 0.63-0.87% of the mass fraction of molten steel entering the ladle. Nano-scale grains have a very large specific surface area, and the surface energy and surface binding energy of the grains are large. When the nano-crystalline modifier is added to the molten steel, it is easy to become an effective core for the nucleation of the molten steel, thereby promoting the non-uniformity of the molten steel. Nucleation, increase the nucleation rate, refine the microstructure of aluminum-boron high-speed steel, and improve the mechanical properties of aluminum-boron high-speed steel. In addition, the nanocrystalline modifier has good wettability and diffusion rate in molten steel, which is caused by the interfacial correlation effect of nanomaterials, which makes the diffusion speed of the nanocrystalline modifier in molten steel very fast, and can be quickly dispersed. In the molten steel, it is ensured that the effective heterogeneous nucleation nuclei in the molten steel exist in a large number and in a dispersed manner. Amorphous crystals have no fixed melting and boiling points, so when the amorphous modifier is added to molten steel, it will not melt immediately. The nanocrystals are dispersed and wrapped in the non-crystal so that it has a certain time before melting to exert the efficiency of promoting heterogeneous nucleation. When the temperature of the molten steel drops to 1483-1526° C., the molten steel is poured into a mold to obtain a high-speed steel roll blank containing aluminum and boron. After rough machining, the aluminum-boron-containing high-speed steel roll blank is heated in the furnace to 1055-1080°C and kept for 2-4 hours. The main purpose is to ensure the austenitization of the matrix at high temperature and increase the amount of alloying elements in the austenite. Then cool quickly at a rate of 18-22°C/min until the temperature is lower than 250°C, mainly to obtain high-hardness martensite and bainite. Finally, it is put into the furnace and heated to 500-540°C. After 12-15 hours of heat preservation, the furnace is cooled until the temperature is lower than 160°C, and the furnace is air-cooled to room temperature. The main purpose is to stabilize the roll structure and eliminate the internal stress of the roll.

Compared with the prior art, the present invention has the following advantages:

1) The roll of the present invention does not contain expensive elements such as cobalt, nickel, niobium, tungsten, etc., so that the cost of the roll is greatly reduced;

2) The roll of the present invention has excellent oxidation resistance and high temperature temper softening resistance, and the red hardness at 600°C exceeds 60HRC;

3) The hardness of the roll of the present invention is greater than 62HRC, the tensile strength is greater than 800MPa, and the impact toughness is greater than 12J/cm2. On a hot rolling mill, the service life is increased by more than 450% compared with ordinary high-nickel-chromium cast iron rolls.

detailed description

The present invention will be described in further detail below in conjunction with the examples, but the present invention is not limited to the following examples.

Example 1:

An aluminum-boron-containing high-speed steel roll is characterized in that it is smelted in an electric furnace, and the specific preparation process steps are:

1) Melt aluminum-boron high-speed steel in a 500 kg medium-frequency induction furnace first. The chemical composition and mass fraction of the aluminum-boron high-speed steel molten steel are 1.67C, 1.36B, 1.05Al, 5.37Cr, 2.17Mo, 0.99Si, 0.67Mn, 1.36V, 0.019S, 0.028P, the balance Fe, when the temperature of the molten steel reaches 1623°C, the molten steel is taken out of the furnace into the ladle, and the bottom of the ladle is pre-added with an amorphous and nanocrystalline modifier with a thickness of 0.18mm. The chemical composition and mass fraction of the modifier is 21.60% B, 1.23% Rb, 21.69% Al, 3.66% Ti, 1.08% C, 5.21% Ca, the balance is Fe and inevitable impurity elements, amorphous and nanocrystalline modification The amount of additive added accounts for 0.63% of the mass fraction of the molten steel entering the ladle. When the temperature of the molten steel drops to 1483° C., the molten steel is poured into the mold to obtain the aluminum-boron high-speed steel roll blank;

2) After rough processing, the aluminum-boron high-speed steel roll blank is heated in the furnace to 1060°C, and after 3 hours of heat preservation, it is rapidly cooled at a rate of 20°C/min until the temperature is lower than 250°C, and then heated in the furnace to 520°C. After 14 hours of heat preservation, cool in the furnace until the temperature is lower than 160°C, air-cool to room temperature after taking out the furnace, and finally finish machining to the specified size and precision to obtain the aluminum-boron high-speed steel roll. The specific mechanical properties are shown in Table 1.

Example 2:

An aluminum-boron-containing high-speed steel roll is characterized in that it is smelted in an electric furnace, and the specific preparation process steps are:

1) Melt aluminum-boron high-speed steel in a 1000 kg medium-frequency induction furnace first. The chemical composition and mass fraction of aluminum-boron high-speed steel molten steel are 1.92C, 1.13B, 1.28Al, 5.04Cr, 2.55Mo, 0.78Si, 0.94Mn, 1.14V, 0.025S, 0.026P, the balance Fe, when the temperature of the molten steel reaches 1648°C, the molten steel is taken out of the furnace into the ladle, and the bottom of the ladle is pre-added with an amorphous and nanocrystalline modifier with a thickness of 0.69mm. The chemical composition and mass fraction of the modifier is 20.34% B, 1.44% Rb, 21.47% Al, 4.01% Ti, 0.91% C, 5.56% Ca, the balance is Fe and inevitable impurity elements, amorphous and nanocrystalline modification The amount of additive added accounts for 0.87% of the mass fraction of the molten steel entering the ladle. When the temperature of the molten steel drops to 1526°C, the molten steel is poured into the mold to obtain the aluminum-boron high-speed steel roll blank;

2) After rough processing, the aluminum-boron high-speed steel roll blank is heated in the furnace to 1055°C, and after 4 hours of heat preservation, it is rapidly cooled at a rate of 18°C/min until the temperature is lower than 250°C, and then heated in the furnace to 540°C. After heat preservation for 12 hours, cool in the furnace until the temperature is lower than 160°C, air cool to room temperature after taking out the furnace, and finally finish machining to the specified size and precision to obtain the aluminum-boron high-speed steel roll. The specific mechanical properties are shown in Table 1.

Example 3:

An aluminum-boron-containing high-speed steel roll is characterized in that it is smelted in an electric furnace, and the specific preparation process steps are:

1) Melt aluminum-boron high-speed steel in a 750 kg medium-frequency induction furnace first. The chemical composition and mass fraction of the aluminum-boron high-speed steel molten steel are 1.82C, 1.19B, 1.20Al, 5.25Cr, 2.46Mo, 0.90Si, 0.85Mn, 1.27V, 0.022S, 0.031P, the balance Fe, when the temperature of the molten steel reaches 1641°C, the molten steel is taken out of the furnace into the ladle, and the bottom of the ladle is pre-added with an amorphous and nanocrystalline modifier with a thickness of 0.54mm. The chemical composition and mass fraction of the modifier is 20.99% B, 1.28% Rb, 21.53% Al, 3.84% Ti, 0.97% C, 5.41% Ca, the balance is Fe and inevitable impurity elements, amorphous and nanocrystalline modification The amount of additive added accounts for 0.75% of the mass fraction of the molten steel entering the ladle. When the temperature of the molten steel drops to 1498° C., the molten steel is poured into the mold to obtain the aluminum-boron high-speed steel roll blank;

2) After rough processing, the aluminum-boron high-speed steel roll blank is heated in the furnace to 1080°C, and after holding for 2 hours, it is rapidly cooled at a rate of 22°C/min until the temperature is lower than 250°C, and then heated in the furnace to 500°C. After heat preservation for 15 hours, cool in the furnace until the temperature is lower than 160°C, air cool to room temperature after taking out the furnace, and finally finish machining to the specified size and precision to obtain the aluminum-boron high-speed steel roll. The specific mechanical properties are shown in Table 1.

Table 1 Mechanical properties of aluminum-boron high-speed steel rolls

The aluminum-boron high-speed steel roll of the invention does not contain expensive cobalt, nickel, niobium, tungsten and other elements, so that the cost of the roll is greatly reduced. The roll of the invention has excellent oxidation resistance and high temperature temper softening resistance, especially excellent red hardness, and the red hardness at 600 DEG C exceeds 60HRC. The roll hardness of the present invention is greater than 62HRC, the tensile strength is greater than 800MPa, and the impact toughness is greater than 12J/cm ² . It is used on hot rolling mills for strip steel, rods, and wire rods. The service life of the aluminum-boron high-speed steel roll of the present invention is longer than that of ordinary high-nickel-chromium cast iron rolls. Improve over 450%. Popularization and application of the achievements of the invention can reduce the consumption of rolls, increase the operating rate of rolling mills, and reduce the labor intensity of workers. The popularization and application has good economic and social benefits.

Claims (2)

1. a kind of preparation method of aluminum-boron high-speed steel roll is characterized in that, adopts electric furnace smelting, and concrete preparation process step is: 1) Melting aluminum-boron high-speed steel in an induction furnace first, the chemical composition and mass fraction of aluminum-boron high-speed steel molten steel are 1.67～1.92C, 1.13～1.36B, 1.05～1.28Al, 5.04～5.37Cr, 2.17 ～2.55Mo, 0.78～0.99Si, 0.67～0.94Mn, 1.14～1.36V, <0.030S, <0.032P, balance Fe; An amorphous and nanocrystalline modifier with a thickness of 0.15 to 0.80 mm is added, and the chemical composition and mass fraction of the amorphous and nanocrystalline modifier are 20.34 to 21.60% B, 1.23 to 1.44% Rb, 21.47 to 21.69% Al, and 3.66 to 4.01 %Ti, 0.91～1.08%C, 5.21～5.56%Ca, the balance is Fe and unavoidable impurity elements; the addition of amorphous and nanocrystalline modifier accounts for 0.63～0.87% of the mass fraction of molten steel entering the ladle, when the molten steel temperature When the temperature is lowered to 1483-1526°C, the molten steel is poured into the mold to obtain the aluminum-boron high-speed steel roll blank; 2) After rough processing, the aluminum-boron high-speed steel roll blank is heated in the furnace to 1055-1080°C, and after 2-4 hours of heat preservation, it is rapidly cooled at a rate of 18-22°C/min until the temperature is lower than 250°C, and then put into Heating the furnace to 500-540°C, keeping it warm for 12-15 hours, cooling with the furnace until the temperature is lower than 160°C, taking it out of the furnace and air-cooling to room temperature, and finally finishing to the specified size and precision to obtain the aluminum-boron high-speed steel roll. 2. a kind of aluminum-containing boron high-speed steel roll prepared according to the method for claim 1.