CN111850398A - Free-cutting pre-hardened plastic die steel with high corrosion resistance and preparation method thereof - Google Patents
Free-cutting pre-hardened plastic die steel with high corrosion resistance and preparation method thereof Download PDFInfo
- Publication number
- CN111850398A CN111850398A CN202010644684.4A CN202010644684A CN111850398A CN 111850398 A CN111850398 A CN 111850398A CN 202010644684 A CN202010644684 A CN 202010644684A CN 111850398 A CN111850398 A CN 111850398A
- Authority
- CN
- China
- Prior art keywords
- die steel
- steel
- corrosion resistance
- equal
- plastic die
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
- B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention provides a free-cutting pre-hardened plastic die steel with high corrosion resistance and a preparation method thereof, wherein the steel comprises the following components in percentage by weight: c: 0.40% -0.48%, Si: 0.45% -0.68%, Mn: 1.50 to 1.85 percent of the total weight of the composition, and less than or equal to P0.015 percent, less than or equal to 0.015 percent of S, Cr: 2.50% -3.50%, Mo: 0.10% -0.15%, Cu: 0.20% -0.30%, Ni: 0.15% -0.25%, Sn: 0.05% -0.10%, Zr: 0.04-0.09% of Fe, 1.10-2.00% of Sn/Zr, 0.35-0.45% of Cu + Sn + Zr and the balance of Fe and inevitable impurities; the preparation method comprises the steps of molten iron pretreatment, converter smelting, LF-RH, continuous casting, stacking and slow cooling, slab heating, rolling, straightening, slow cooling and heat treatment; the die steel produced by the invention has the pre-hardening hardness of 36-38HRC, the homogeneity degree is less than or equal to 2HRC, and the transverse impact property KV260J-63J, 68J-70J longitudinal impact performance, excellent corrosion resistance and easy cutting performance.
Description
Technical Field
The invention belongs to the technical field of metal material production, and particularly relates to free-cutting pre-hardened plastic die steel with high corrosion resistance and a preparation method thereof.
Background
With the rapid development of plastic industry in China and the appearance of specialized mold manufacturing plants, the demand for plastic product forming mold steel is more and more large, and the requirements for the performance and the quality of the steel are also more and more high. The original common steel grades can not meet the requirements of new product new process development. Plastics are not generally considered to be corrosive, but there are circumstances in which they may release corrosive components during their production. The PVD process releases hydrochloric acid. Some plastics such as polyvinyl chloride, fluoroplastic and flame-retardant ABS can decompose corrosive gases such as hydrogen chloride, hydrogen fluoride and sulfur dioxide, and have a certain corrosion effect on the mold. Therefore, the mold for such plastic products is required to have good corrosion resistance, and at the same time, the plastic mold steel is required to have good cutting performance in order to facilitate the processing of the mold by downstream users, improve the production efficiency of the mold, and reduce the production period.
A lot of works are done by many domestic units in the aspects of developing corrosion-resistant free-cutting plastic die steel, improving the quality of metallurgy and rolling forging, optimizing the heat treatment process, prolonging the service life of the die and the like.
The invention relates to a production method of a free-cutting plastic die steel plate (application number: 201310569068.7), which comprises the following steps: c: 0.35% -0.45%, Si: 0.25% -0.35%, Mn: 1.50% -1.60%, P is less than or equal to 0.008, S: 0.05% -0.10%, Cr: 1.80% -2.00%, Mo: 0.15 to 0.20 percent of the total weight of the alloy, and the balance of impurities and Fe. The steel plate of the free-cutting plastic die with the thickness of less than 120mm is produced, the hardness is 30-36HRC, the difference is less than +/-0.5 HRC, and the first-grade ultrasonic flaw detection is qualified. But the method can only ensure the uniform hardness of the surface of the steel plate, can not ensure the uniform hardness of the steel plate in the thickness section direction, and can not give consideration to the corrosion resistance.
The invention discloses a sulfur-containing plastic die steel thick plate (application number: 201510384732.X), which overcomes the problems of serious segregation of sulfides and loosening of the interior of a steel plate in the existing sulfur-containing die steel, obtains better internal quality through a series of processes, ensures uniform steel plate tissues and the cutting performance of the steel plate, but cannot ensure the isotropic performance and the corrosion resistance of the steel plate.
The invention discloses plastic die steel and a preparation method thereof (application number: 201710381394.3), wherein the plastic die steel comprises the following components in percentage by weight: c: 0.16-0.26%, Si is less than or equal to 1%, Mn is less than or equal to 1%, Cr: 11% -16%, N: 0.06% -0.16%, Mo: 0.10 to 0.25 percent of the total weight of the alloy, and the balance of impurities and Fe. The plastic die steel has good hardness and corrosion resistance, but the cutting performance is inevitably reduced due to the high hardness.
The invention discloses free-cutting plastic die steel and a heat treatment method thereof (application number: 201510897021.2), and the plastic die steel comprises the following components: 0.26-0.28, Mn: 1.4-1.8, Si: 0.4-0.5, Cr: 1.3-1.5, Mo: 0.2-0.4, S: 0.06-0.07, Pb: 0.06-0.07, less than or equal to 0.01 of N, less than or equal to 0.025 of P, less than or equal to 0.1 of Cu, less than or equal to 0.15 of Ni, and the addition of S and Pb in the components improves the cutting performance of the die steel, so that the die steel has higher hardness, but cannot ensure impact toughness and performance homogeneity, meanwhile, the Pb-containing steel has serious segregation, and the pollution caused by lead steam generated in the lead-adding process is difficult to solve, so that the production of the die steel is limited from the environmental protection perspective.
The plastic die steel disclosed in the invention (application number: 201810447593.4) comprises the following chemical components: c: 0.45% -0.52%, Si: 0.30% -0.60%, Mn: 1.20-1.50%, P is less than or equal to 0.030%, S is less than or equal to 0.030%, Cr: 0.20% -0.40%, V: 0.10% -0.15%, Ti: 0.010% -0.030%, N: 0.008% -0.0120%. The hardness of the obtained die steel reaches 28-36HRC, but the uniform performance of the section hardness in the thickness direction is difficult to ensure
Disclosure of Invention
The invention aims to overcome the problems and the defects and provide the free-cutting pre-hardened plastic die steel with high corrosion resistance and the preparation method thereof.
The purpose of the invention is realized as follows:
the free-cutting pre-hardened plastic die steel with high corrosion resistance comprises the following components in percentage by weight: c: 0.40% -0.48%, Si: 0.45% -0.68%, Mn: 1.50-1.85%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Cr: 2.50% -3.50%, Mo: 0.10% -0.15%, Cu: 0.20% -0.30%, Ni: 0.15% -0.25%, Sn: 0.05% -0.10%, Zr: 0.04-0.09% of the total weight of the alloy, 1.10-2.00% of Sn/Zr, 0.35-0.45% of Cu + Sn + Zr and the balance of Fe and inevitable impurities.
The plastic die steel has the pre-hardening hardness of 36HRC-38HRC, the homogeneity degree of less than or equal to 2HRC, the transverse impact property of 60J-63J and the longitudinal impact property of KV2The thickness of the die steel plate reaches 68J-70J, and the thickness of the die steel plate is 10-180 mm.
The invention adopts the design idea of increasing Si and reducing Mo, and compounding Cu, Sn and Zr to improve the cutting performance of the die steel and adopts the design idea of improving the corrosion resistance and the strength of the die steel by compounding and adding Cr and Cu, thereby improving the strength hardness and the corrosion resistance of the plastic die steel on one hand, and saving the cost because Mo is a noble metal on the other hand.
The invention has the following design reasons:
c: carbon can form dispersed alloy carbide in steel, so that the carbon has great influence on strength, plasticity and toughness, weldability and the like and is also a key factor for controlling the strength of martensite. In the case of plastic die steels, a portion of the carbon in the steel enters the matrix of the steel to cause solid solution strengthening, and another portion of the carbon will combine with carbide-forming elements in the alloying elements to form alloyed carbides. Too high carbon content is not favorable for cutting performance, and too low carbon content affects strength hardness and wear resistance of the die steel. In order to ensure the comprehensive performance of the plastic die steel and simultaneously benefit the cutting performance, the content of the added C is 0.40-0.48 percent.
Si: silicon is one of important elements for strengthening ferrite, can obviously improve the strength and hardness of steel, can improve the quenching temperature and improves the hardenability. When in a strong oxidizing medium, Si can improve the corrosion resistance of steel, and research shows that Si has good Cl resistance like Mo-The corrosion performance is higher, the higher the Si content in the steel is, the more positive the pitting potential is, the less corrosion is, and the effect of Si on medium carbon steel is better than that of Mo. Silicon is also a ferrite forming element, reduces an austenite phase region, can improve hardenability and basic strength, and is beneficial to secondary hardening. The silicon at the temperature of 540-580 ℃ can improve the dispersion degree of alloy carbide separated out in the tempering process of the die steel and can increase the secondary hardening peak. And meanwhile, the migration rate of carbon is limited, so that precipitated carbide is not easy to grow, the structure of the carbide is more stable, and the chemical stability of the steel is improved. However, the excessive amount of Si makes the spheroidized carbide particles larger in diameter and larger in spacing, and at the same time promotes segregation, resulting in the formation of a band-shaped structure, making the transverse properties lower than the longitudinal properties, so that the Si content is selected to be 0.45-0.68%.
Mn: the Mn-containing steel is a solid solution strengthening element in the steel, the crystal grains are refined, the ductile-brittle transition temperature is reduced, the hardenability is improved, and the Mn-containing steel can change the property and the shape of an oxide formed during the solidification of the steel. Meanwhile, the high-strength. The content of Mn added is 1.50-1.85%.
P, S: all are free-cutting elements. S is distributed in the steel in the form of MnS, the MnS inclusion cuts off the continuity of a matrix structure, so that the cutting chips are easy to break, and the abrasion of a cutter is reduced due to the lubricating action of MnS, so that the cutting performance of the steel is improved. MnS extends along the rolling direction in the hot rolling process, so that the transverse mechanical property of the sulfur free-cutting steel is obviously reduced, and the anisotropy of the steel is enhanced. Meanwhile, S is harmful to the corrosion resistance of the die steel and deteriorates the welding performance, so that S series additive elements are not adopted as forming elements of the free-cutting phase in the invention. Although P can increase ferrite hardness in a proper amount and improve the surface finish and machinability of parts, too high P in steel increases cold brittleness, and too much S, P affects the homogeneity and purity of the steel. Therefore, P is less than or equal to 0.015 percent and S is less than or equal to 0.015 percent are selectively added.
Cr: part of the chromium is dissolved in the matrix to play a role in solid solution strengthening, and the other part of the chromium is combined with the carbon to form carbide. Chromium is dissolved in austenite during quenching and heating and is dissolved in martensite after quenching, so that the tempering softening resistance of the steel can be improved, the chromium is separated out from a matrix during tempering, alloy carbides are generally formed, and the chromium tends to coarsen along with the increase of the tempering temperature and the prolonging of time. Chromium has a favourable effect on the wear resistance, high temperature strength, as well as on the as-rolled hardness, toughness and hardenability of the steel. For plastic die steel, the corrosion potential of Cr is more negative than that of Fe, so that Fe can be passivated, and the corrosion resistance of the plastic die steel is improved, therefore, the content of Cr added is 2.50-3.50%.
Mo: molybdenum is a strong carbide former element and enhances the hardenability of steel in steel, while Mo is formed in steel2C. MoC and Mo6C carbide, three kinds of carbide all have higher hardness and higher decomposition temperature. During the tempering at the temperature of 540-580 ℃ in the invention, more fine short rod-shaped Mo is separated out from the die steel2And C, improving the secondary hardening capacity and the tempering stability. However, mine resources containing molybdenum are limited, the price is high, and the toughness may be reduced due to the high content of molybdenum in steel. The invention adopts the design idea of increasing Si and reducing Mo, improves the corrosion resistance on the basis of ensuring the comprehensive mechanical property and reduces the cost, so the content of Mo added is selected to be 0.10-0.15 percent.
Cu: cu plays a role in improving the cutting performance, plays a role in lubricating the die steel, and promotes heat outflow due to Cu-rich phases, so that the Cu-rich phases are uniformly dispersed in a steel matrix. The effect of Cu-rich relative machinability may be due to lubrication and thermal conductivity of the cutting toolIs caused by the reduction of friction at the sloped surface. Secondly, the corrosion resistance of the die steel is improved, Cu plays a role of activating an anode to promote the steel to generate cathode passivation so as to slow down corrosion, and on the other hand, the harmful effect of S can be counteracted because of the dissolved Cu+Then deposited on the surface of Fe and adsorbed S2-Ion formation of Cu2S, insoluble in acid. Thus can eliminate S2-Catalysis of the electrochemical reaction by the ions. Thirdly, the copper phase particles grow into rod-shaped copper particles, which play a role in precipitation strengthening and improve the yield strength of the plastic die steel. However, since excessive Cu content not only wastes valuable Cu but also causes hot shortness, the Cu content in the present invention is 0.20 to 0.30%.
Ni: the strength, hardenability and toughness of the plastic die steel can be improved. When a certain amount of Ni is contained in the steel, certain physical properties of the steel can be changed, and the corrosion resistance of the steel in a reducing medium is improved. In the invention, 0.20-0.30% of Cu is added, and a layer of deposited copper can be formed on the surface of the steel sometimes in production due to low solubility of Cu in the steel. If the steel is hot worked above the copper melting point, the copper deposited on the surface will form a liquid film, which will wet the surface of the steel and wet along the grain boundaries into the interior of the steel, eventually leading to severe copper cracking. Therefore, a certain amount of Ni is added, so that a copper-enriched layer on the surface of the steel is changed into a copper-nickel enriched layer with the melting point of over 1200 ℃, copper cracking is avoided, and meanwhile, Ni element plays a role in improving the strength, hardness, hardenability and toughness of the steel, so that the Ni content is 0.15-0.25%.
Sn, Zr: the cutting performance of the plastic die steel can be improved. Sn can effectively play a role of a lubricant after being heated, softened and melted in cutting processing, so that chips are easy to curl, the brittleness is improved by enriching to the vicinity of defects and inclusions, hard lines segregated at the positions of the defects and the inclusions are compensated, and the performance of a steel plate is uniform. Zr can control the form of sulfide to reduce the difference of longitudinal and transverse mechanical properties caused by the long-strip sulfide, improve the cutting performance and simultaneously improve the isotropic performance of the plastic die steel. However, too high Zr content tends to deteriorate the high temperature plastic workability of the plastic die steel, makes it difficult to stretch the steel during rolling, and limits the anisotropy of the strength of the steel sheet, and too high Sn content tends to deteriorate the mechanical properties of the steel sheet. Therefore, the composite action of Sn, Zr and Cu can improve the cutting performance of the plastic die steel and simultaneously improve the strength and hardness in a certain proportion, and the plastic toughness is not influenced, so that the ratio of Sn: 0.05% -0.10%, Zr: 0.04-0.09% of the total weight of the alloy, 1.10-2.00% of Sn/Zr and 0.35-0.45% of Cu + Sn + Zr.
The second technical scheme of the invention provides a preparation method of the free-cutting pre-hardened plastic die steel with high corrosion resistance, which comprises the steps of molten iron pretreatment, converter smelting, LF-RH, continuous casting, stacking and slow cooling, slab heating, rolling, straightening, slow cooling and heat treatment;
Continuous casting: the secondary cooling specific water amount is controlled to be 2.0-2.5L/kg, and the secondary cooling water strength has an important effect on improving the center segregation of the continuous casting slab. When the secondary cooling specific water amount is small in the continuous casting process, the distance between secondary dendritic crystal arms is increased, the permeability of a mushy zone is increased rapidly, the permeability reaches the maximum value at the position close to the center line, and solute is enriched continuously and pushes towards the center of a casting blank to cause the central segregation to be aggravated. The central carbon segregation and the manganese segregation of the continuous casting slab are reduced along with the increase of the secondary cooling specific water amount. The growth rate of the dendritic crystal of the continuous casting billet is improved due to the increase of the secondary cooling specific water amount, and the specific gravity segregation caused by crystal precipitation is prevented by a dendritic crystal framework formed by the separated fine dendritic crystal, so that the subsequent molten steel participating in slow solidification is reduced, and the generation of the center segregation is inhibited.
The interval fs of the plastic die steel under light press is 0.5-0.8, and fs is the central solid fraction of the continuous casting billet; the light pressing amount is 2.8-3.2 mm. The solidification shrinkage of the continuous casting billet is compensated by applying pressure near the tail end of the liquid core of the continuous casting billet under the soft reduction. The molten steel continuous casting device can eliminate or reduce internal gaps formed by continuous casting billet shrinkage, prevent molten steel with intercrystalline enriched solute elements from transversely flowing to the center of the casting billet, and promote the redistribution of the solute elements in the molten steel, so that a cast solidification structure is more uniform and compact, the effect of improving central segregation is achieved, and good internal quality of the continuous casting billet can be obtained. The reduction interval and the reduction are main process parameters of the dynamic soft reduction technology. The optimal soft reduction implementation interval of the plastic die steel is at the position of 0.3-0.7 of the central solid phase rate of the continuous casting billet; the flow of solute-enriched molten steel can be prevented only by completely compensating the volume shrinkage of molten steel in the solidification process in the soft reduction interval by the soft reduction, but cracks are generated in the continuous casting billet due to overlarge reduction, and the clamping roller under the soft reduction is damaged; the reduction is too small, the improvement on the center segregation is not obvious, the solid phase rate fs is set to be 0.5-0.8 aiming at the light reduction interval of the continuous casting billet with the thickness of 300mm, and the light reduction is set to be 2.8-3.2 mm.
Compared with the traditional die steel, the heating temperature of the plate blank is reduced, the temperature is controlled at 1100-1150 ℃, the heat preservation is carried out for 280-320 min, the coarse austenite grains and the tissue heredity are avoided, namely the old phase grains are coarse, and the newly formed grains are also coarse, so that the subsequent quenching cracking is prevented. The initial rolling temperature of the plate blank is controlled to be more than or equal to 1050 ℃, the rolling process of high temperature, low speed and large reduction is adopted, and the reduction rate of the first four passes is 20-25 percent; by adopting a transverse-longitudinal alternate rolling mode, the pass reduction is increased on the premise of ensuring the safety of equipment, the penetrating power of the rolling force is improved, the deformation penetrates into the center of the blank, and the coarse dendrites are smashed, so that the influence of the original defects of the continuous casting billet can be effectively reduced. The finish rolling temperature is 900-950 ℃, the reduction rate of the first two passes is 20-24%, the finished product thickness is 10-180mm, and the offline temperature of the steel plate is 300-450 ℃. And (4) immediately stacking and slowing down the line by adopting a mode of laying down and covering up, wherein the slow cooling time is 18-26 h.
And then carrying out heat treatment, wherein the plastic die steel is subjected to sub-temperature quenching, the quenching temperature is controlled to be 790-plus 830 ℃, the heating rate is 1.5-2.0min/mm, the net heat preservation time is 2-5h according to different thicknesses, the steel plate is precooled in the air for 60-90s after being taken out of the furnace, and then water cooling is carried out continuously. The austenite grains of the plastic die steel applying the heat treatment technology of the invention are smaller than those of the traditional quenching, because the austenite grain growth rate is lower than that of the traditional quenching, the quenching temperature is lower, so that the die steel can not be completely austenitized, the structure after quenching contains ferrite, but the mechanical property is still close to that of the traditional quenching due to the fine grain function. The sub-temperature quenching is beneficial to reducing the thermal stress during quenching, and the structure stress is small when the austenite is transformed into the martensite, so that the sub-temperature quenching has smaller thermal stress and structure stress than the common quenching, and the quenching distortion can be effectively avoided. The precooling of the steel plate is to reduce the surface temperature of the steel plate, so that the total heat capacity of the steel plate is reduced, the cooling speed of the steel plate is increased, more quenched martensite and/or lower bainite are obtained, and the mechanical property of the steel plate is improved to make up the influence of sub-temperature quenching on the performance.
Then tempering; the tempering temperature is 540-.
The invention has the beneficial effects that: the invention adopts the compound action of increasing Si and reducing Mo, Cu, Sn and Zr to improve the cutting performance of the die steel, adopts the design idea of improving the corrosion resistance and the strength of the die steel by the compound addition of Cr and Cu, and is matched with the production of the process of continuous casting, slab low-temperature heating, sub-temperature quenching, furnace discharge precooling and one-time tempering, so that the plastic die steel has the pre-hardening hardness of 36HRC-38HRC, the homogeneity degree is less than or equal to 2HRC and the transverse impact property KV is KV260J to 63J, the longitudinal impact performance reaches 68J to 70J, and the corrosion rate is less than or equal to 7.48g/m after being soaked in 5 percent hydrochloric acid for 48 hours2·h; under the conditions that the fixed feed amount is 2mm, the feed amount is 0.2mm/rev, the back cutting amount is 2mm and the cutting speed is 50mm/min, the abrasion loss of a tool nose is less than or equal to 0.05mm, the abrasion loss of a rear tool face is less than or equal to 0.10mm, and the corrosion resistance and the free-cutting property are excellent. The pre-hardened die steel plastic die steel completely meets the requirements of life and production on the comprehensive performance of plastic die steel at present, is superior to foreign advanced die steel, and can realize replacement import.
Detailed Description
The present invention is further illustrated by the following examples.
According to the technical scheme, the method comprises the steps of molten iron pretreatment, converter smelting, LF-RH, continuous casting, stacking and slow cooling, slab heating, rolling, straightening, slow cooling and heat treatment.
Continuous casting: controlling the secondary cooling specific water amount to be 2.0-2.5L/kg, the interval of fs being 0.5-0.8 under light pressure and the amount of light pressure being 2.8-3.2 mm; heating the plate blank at 1100-1150 deg.c for 280-320 min; the initial rolling temperature of the plate blank is controlled to be equal to or more than 1050 ℃, the reduction rates of the first four passes are 20-25%, a horizontal-longitudinal alternate rolling mode is adopted, the finish rolling temperature is 900-950 ℃, the reduction rates of the first two passes are 20-24%, and the steel plate offline temperature is 300-450 ℃; and (4) after the production line is down, stacking is slow, and slow cooling time is 18-26 h.
Then, carrying out heat treatment, adopting sub-temperature quenching, wherein the quenching temperature is 790-830 ℃, the heating rate is 1.5-2.0min/mm, the net heat preservation time is 2-5h, precooling the steel plate in air for 60-90s after discharging, and then continuing water cooling; then tempering is carried out, wherein the tempering temperature is 540-580 ℃; the heating rate is 1.5-2.0min/mm in the tempering process, and the net heat preservation is carried out for 3-6 h.
Further, the method comprises the following steps of; and the interval fs under the light pressure is 0.3-0.7.
The compositions of the steels of the examples of the invention are shown in table 1. The main continuous casting and continuous casting billet heating process parameters of the steel of the embodiment of the invention are shown in the table 2. The main rolling and cooling process parameters of the steels of the examples of the invention are shown in table 3. The main heat treatment process parameters of the steels of the examples of the invention are shown in Table 4. The Rockwell hardness of the steels of the examples of the present invention is shown in Table 5. The impact toughness of the steels of the examples of the invention are shown in Table 6. The corrosion resistance of the steel of the invention is shown in Table 7. The cutting force of the steel, the tool nose abrasion amount after cutting for 50min and the flank surface abrasion amount are shown in Table 8.
TABLE 1 composition (wt%) of steels of examples of the present invention
TABLE 2 Main continuous casting and continuous casting billet heating process parameters of the steels of the examples of the present invention
TABLE 3 Main Rolling and Cooling Process parameters for steels according to the examples of the invention
TABLE 4 Main Heat treatment Process parameters of the steels of the examples of the invention
TABLE 5 Rockwell hardness of steels according to examples of the invention
TABLE 6 impact toughness of steels of examples of the invention
TABLE 7 Corrosion resistance of inventive steels
| Examples | Corrosion rate (g/m)2·h) |
| 1 | 6.53 |
| 2 | 7.48 |
| 3 | 5.89 |
| 4 | 6.89 |
| 5 | 7.43 |
| 6 | 6.34 |
| 7 | 7.37 |
| 8 | 6.50 |
| 9 | 7.41 |
| 10 | 6.10 |
Remarking: soaking in 5% hydrochloric acid for 48 hr for corrosion.
TABLE 8 cutting force of the inventive steels, and tool nose and flank wear amounts after 50min of cutting
| Examples | Cutting force (N) | Abrasion loss of tool nose (mm) | Flank wear (mm) |
| 1 | 1415 | 0.030 | 0.080 |
| 2 | 1410 | 0.035 | 0.090 |
| 3 | 1417 | 0.04 | 0.085 |
| 4 | 1420 | 0.05 | 0.095 |
| 5 | 1425 | 0.038 | 0.100 |
| 6 | 1427 | 0.041 | 0.087 |
| 7 | 1430 | 0.044 | 0.094 |
| 8 | 1419 | 0.038 | 0.091 |
| 9 | 1414 | 0.049 | 0.086 |
| 10 | 1421 | 0.031 | 0.083 |
Remarking: the fixed feed rate is 2mm, the feed rate is 0.2mm/rev, the back cut rate is 2mm, and the cutting speed is 50 mm/min.
In order to express the present invention, the above embodiments are properly and fully described by way of examples, and the above embodiments are only used for illustrating the present invention and not for limiting the present invention, and those skilled in the relevant art can make various changes and modifications without departing from the spirit and scope of the present invention, and any modifications, equivalent substitutions, improvements, etc. made by the persons skilled in the relevant art should be included in the protection scope of the present invention, and the protection scope of the present invention should be defined by the claims.
Claims (4)
1. The free-cutting pre-hardened plastic die steel with high corrosion resistance is characterized by comprising the following components in percentage by weight: c: 0.40% -0.48%, Si: 0.45% -0.68%, Mn: 1.50-1.85%, P is less than or equal to 0.015%, S is less than or equal to 0.015%, Cr: 2.50% -3.50%, Mo: 0.10% -0.15%, Cu: 0.20% -0.30%, Ni: 0.15% -0.25%, Sn: 0.05% -0.10%, Zr: 0.04-0.09% of the total weight of the alloy, 1.10-2.00% of Sn/Zr, 0.35-0.45% of Cu + Sn + Zr and the balance of Fe and inevitable impurities.
2. The free-cutting pre-hardened plastic die steel with high corrosion resistance as claimed in claim 1, wherein the pre-hardened hardness of the plastic die steel is 36-38HRC, the homogeneity degree is less than or equal to 2HRC, and the transverse impact property KV 2The thickness of the die steel plate is 60-63J, the longitudinal impact performance reaches 68-70J, and the thickness of the die steel plate is 10-180 mm.
3. A method for preparing the free-cutting pre-hardened plastic die steel with high corrosion resistance of claim 1 or 2, comprising the steps of molten iron pretreatment, converter smelting, LF-RH-continuous casting, stacking and slow cooling, slab heating, rolling, straightening, slow cooling and heat treatment; the method is characterized in that:
continuous casting: controlling the secondary cooling specific water amount to be 2.0-2.5L/kg, the interval of fs being 0.5-0.8 under light pressure and the amount of light pressure being 2.8-3.2 mm; heating the slab at 1100-1150 ℃ for 280-320 min; the slab rolling temperature is controlled to be equal to or higher than 1050 ℃, the reduction rates of the first four passes are 20-25%, a horizontal-longitudinal alternate rolling mode is adopted, the finish rolling temperature is 900-; after the wire is off, stacking and slowly cooling for 18-26 h;
then, carrying out heat treatment, adopting sub-temperature quenching, wherein the quenching temperature is 790-830 ℃, the heating rate is 1.5-2.0min/mm, the net heat preservation time is 2-5h, precooling the steel plate in air for 60-90s after discharging, and then continuing water cooling; then tempering is carried out, wherein the tempering temperature is 540-580 ℃; the heating rate in the tempering process is 1.5-2.0min/mm, and the net heat preservation time is 3-6 h.
4. The method for preparing the free-cutting pre-hardened plastic die steel with high corrosion resistance according to claim 3, wherein the method comprises the following steps: and the interval fs under the light pressure is 0.3-0.7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010644684.4A CN111850398B (en) | 2020-07-07 | 2020-07-07 | Free-cutting pre-hardened plastic die steel with high corrosion resistance and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010644684.4A CN111850398B (en) | 2020-07-07 | 2020-07-07 | Free-cutting pre-hardened plastic die steel with high corrosion resistance and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111850398A true CN111850398A (en) | 2020-10-30 |
| CN111850398B CN111850398B (en) | 2021-08-20 |
Family
ID=73152345
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010644684.4A Active CN111850398B (en) | 2020-07-07 | 2020-07-07 | Free-cutting pre-hardened plastic die steel with high corrosion resistance and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111850398B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113652527A (en) * | 2021-08-14 | 2021-11-16 | 张家港市品杰模塑科技有限公司 | Production process of plastic die steel |
| CN115747670A (en) * | 2022-12-01 | 2023-03-07 | 山西太钢不锈钢股份有限公司 | NAK80 bar finishing heat treatment process suitable for conventional equipment |
| CN116463556A (en) * | 2023-04-28 | 2023-07-21 | 鞍钢股份有限公司 | High-temperature oxidation resistance and high-homogeneity die steel and preparation method thereof |
| CN116463556B (en) * | 2023-04-28 | 2024-05-14 | 鞍钢股份有限公司 | High-temperature oxidation resistance and high-homogeneity die steel and preparation method thereof |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102286698A (en) * | 2010-06-17 | 2011-12-21 | 宝山钢铁股份有限公司 | Plastic mold steel and manufacture method thereof |
| CN102650021A (en) * | 2012-05-28 | 2012-08-29 | 上海大学 | Bainite pre-hardening plastic mold steel and preparation method and heat treatment method thereof |
| CN103710625A (en) * | 2013-12-20 | 2014-04-09 | 莱芜钢铁集团有限公司 | High-toughness plastic die steel and production method thereof |
| CN103866197A (en) * | 2014-03-31 | 2014-06-18 | 江苏联峰能源装备有限公司 | Corrosion-resistant plastic die steel and production method thereof |
| CN103911550A (en) * | 2014-03-24 | 2014-07-09 | 北京科技大学 | Environment-friendly low-carbon high-sulfur and bismuth free-cutting steel with excellent thermoplasticity |
| CN105112794A (en) * | 2015-08-25 | 2015-12-02 | 石家庄钢铁有限责任公司 | Low-cost plastic mold steel and production method thereof |
| CN105200343A (en) * | 2015-10-15 | 2015-12-30 | 芜湖市宝艺游乐科技设备有限公司 | Pre-hardened plastic die steel having high acid corrosion resistance and preparation method thereof |
| CN110230009A (en) * | 2019-05-14 | 2019-09-13 | 鞍钢股份有限公司 | A kind of hot die steel and preparation method thereof with good cutting |
| CN110578103A (en) * | 2019-07-05 | 2019-12-17 | 天津钢研海德科技有限公司 | Novel plastic die steel with high toughness, high polishing and high corrosion resistance and manufacturing method thereof |
-
2020
- 2020-07-07 CN CN202010644684.4A patent/CN111850398B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102286698A (en) * | 2010-06-17 | 2011-12-21 | 宝山钢铁股份有限公司 | Plastic mold steel and manufacture method thereof |
| CN102650021A (en) * | 2012-05-28 | 2012-08-29 | 上海大学 | Bainite pre-hardening plastic mold steel and preparation method and heat treatment method thereof |
| CN103710625A (en) * | 2013-12-20 | 2014-04-09 | 莱芜钢铁集团有限公司 | High-toughness plastic die steel and production method thereof |
| CN103911550A (en) * | 2014-03-24 | 2014-07-09 | 北京科技大学 | Environment-friendly low-carbon high-sulfur and bismuth free-cutting steel with excellent thermoplasticity |
| CN103866197A (en) * | 2014-03-31 | 2014-06-18 | 江苏联峰能源装备有限公司 | Corrosion-resistant plastic die steel and production method thereof |
| CN105112794A (en) * | 2015-08-25 | 2015-12-02 | 石家庄钢铁有限责任公司 | Low-cost plastic mold steel and production method thereof |
| CN105200343A (en) * | 2015-10-15 | 2015-12-30 | 芜湖市宝艺游乐科技设备有限公司 | Pre-hardened plastic die steel having high acid corrosion resistance and preparation method thereof |
| CN110230009A (en) * | 2019-05-14 | 2019-09-13 | 鞍钢股份有限公司 | A kind of hot die steel and preparation method thereof with good cutting |
| CN110578103A (en) * | 2019-07-05 | 2019-12-17 | 天津钢研海德科技有限公司 | Novel plastic die steel with high toughness, high polishing and high corrosion resistance and manufacturing method thereof |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113652527A (en) * | 2021-08-14 | 2021-11-16 | 张家港市品杰模塑科技有限公司 | Production process of plastic die steel |
| CN115747670A (en) * | 2022-12-01 | 2023-03-07 | 山西太钢不锈钢股份有限公司 | NAK80 bar finishing heat treatment process suitable for conventional equipment |
| CN115747670B (en) * | 2022-12-01 | 2024-04-26 | 山西太钢不锈钢股份有限公司 | NAK80 bar finishing heat treatment process suitable for conventional equipment |
| CN116463556A (en) * | 2023-04-28 | 2023-07-21 | 鞍钢股份有限公司 | High-temperature oxidation resistance and high-homogeneity die steel and preparation method thereof |
| CN116463556B (en) * | 2023-04-28 | 2024-05-14 | 鞍钢股份有限公司 | High-temperature oxidation resistance and high-homogeneity die steel and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111850398B (en) | 2021-08-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109957707B (en) | Weather-resistant cold-heading steel wire rod for 1000 MPa-level fastener and production method thereof | |
| CN111826589B (en) | Plastic die steel with high strength and high corrosion resistance and preparation method thereof | |
| CN111235464B (en) | Titanium microalloyed economical high-strength weathering steel and production method thereof | |
| CN111809115B (en) | Super-thick plastic die steel with excellent impact corrosion wear resistance and preparation method thereof | |
| CN107130172B (en) | 400HBW grades of Brinell hardness whole constrictive type high tenacity easily weld special thick wear-resisting steel plate and its manufacturing method | |
| CN111850398B (en) | Free-cutting pre-hardened plastic die steel with high corrosion resistance and preparation method thereof | |
| CN111850399B (en) | Corrosion-resistant plastic die steel with good wear resistance and preparation method thereof | |
| CN112251670A (en) | 690 MPa-grade steel plate with good extensibility and manufacturing method thereof | |
| CN111411311A (en) | Steel for die casting corrosion-resistant chain plate and manufacturing method thereof | |
| CN109957728B (en) | Weather-resistant cold heading steel wire rod for 800 MPa-level fastener and production method thereof | |
| CN114836694B (en) | Marine seawater corrosion fatigue resistant ultra-high strength steel and manufacturing method thereof | |
| CN111378900A (en) | Wear-resistant and corrosion-resistant steel for chain plate and manufacturing method thereof | |
| CN110423949A (en) | A kind of copper bearing steel and production method of the surface without peeling defect | |
| CN115386805A (en) | Low-yield-ratio high-toughness bridge weathering steel and manufacturing method thereof | |
| CN112848552B (en) | Copper-steel solid-liquid composite bimetallic material for ocean engineering and preparation method thereof | |
| CN112063917B (en) | Wear-resistant steel plate for artificial board machine equipment and manufacturing method thereof | |
| CN115094342B (en) | Low-yield-ratio 500MPa weather-resistant bridge steel and preparation method thereof | |
| CN114875331B (en) | 610 MPa-grade thick steel plate with excellent core fatigue performance and production method thereof | |
| CN114000034B (en) | Low-yield-ratio high-strength bainite steel rail and production method thereof | |
| CN113174535B (en) | Large-thickness quenched and tempered FO460 steel plate for ships and manufacturing method thereof | |
| CN113151740B (en) | VL4-4L steel plate with good low-temperature toughness for ship and manufacturing method thereof | |
| CN113832387B (en) | Low-cost ultra-thick 1000 MPa-grade steel plate and manufacturing method thereof | |
| CN114990427A (en) | Hot-rolled corrosion-resistant round steel and preparation method thereof | |
| CN114737116B (en) | 700 MPa-level abrasion-resistant corrosion-resistant steel and manufacturing method thereof | |
| CN113549825B (en) | High-corrosion-resistance super stainless steel for ocean engineering equipment and manufacturing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |