CN111748751A - Non-quenched and tempered steel, manufacturing method thereof and application of non-quenched and tempered steel - Google Patents
Non-quenched and tempered steel, manufacturing method thereof and application of non-quenched and tempered steel Download PDFInfo
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- 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
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- 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
- C21D1/06—Surface hardening
- C21D1/09—Surface hardening by direct application of electrical or wave energy; by particle radiation
- C21D1/10—Surface hardening by direct application of electrical or wave energy; by particle radiation by electric induction
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- 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
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- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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
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- 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
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- 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
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- 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
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract
The invention discloses non-quenched and tempered steel, wherein the tensile strength Rm is 900-1150MPa, the yield strength Rel is more than or equal to 600MPa, the elongation A is more than or equal to 10%, the reduction of area Z is more than or equal to 20%, and the impact energy AKu is more than or equal to 30J; the chemical elements of the non-quenched and tempered steel contain: C. the manufacturing method of the quenched and tempered steel comprises the steps of steel making, blanking, machining, surface induction quenching, tempering, excircle grinding and flaw detection. The non-quenched and tempered steel manufactured by the method has excellent mechanical properties, the traditional quenching and tempering heat treatment process is omitted, the machining allowance is reduced, the production efficiency is improved, and the cutting processability and the wear resistance of the knuckle pin manufactured by the non-quenched and tempered steel are improved.
Description
Technical Field
The invention relates to the technical field of automobile metal material processing application, and relates to non-quenched and tempered steel, a manufacturing method thereof and application of the non-quenched and tempered steel.
Background
The automobile steering knuckle pin is a key connecting piece between an automobile front axle and a wheel, is quite complex in stress in the using process, and not only bears the forces and moments in three directions of the axle head, but also requires higher wear resistance. At present, the traditional quenched and tempered steel 42CrMo is mainly adopted for surface quenching to replace carburized steel 20CrMnTi for carburizing in the industry of domestic trucks, the traditional quenched and tempered heat treatment has long production period, large energy consumption and high manufacturing cost, the 42CrMo steel has surface quenching wear resistance which is not as good as 20CrMnTi, and the traditional quenched and tempered steel has large machining allowance, low production efficiency and high cost.
Disclosure of Invention
The invention aims to provide a non-quenched and tempered steel, a manufacturing method thereof and application of the non-quenched and tempered steel; the problems of low production efficiency and high cost of the traditional quenched and tempered steel are solved.
The invention is realized by the following technical scheme:
the non-quenched and tempered steel is characterized in that the tensile strength Rm is 900-1150MPa, the yield strength Rel is more than or equal to 600MPa, the elongation A is more than or equal to 10%, the reduction of area Z is more than or equal to 20%, and the impact energy AKu is more than or equal to 30J; the non-quenched and tempered steel comprises the following chemical elements in percentage by mass: c: 0.43 to 0.47 percent; si: 0.50-0.80%; mn: 1.20-1.60%; p is less than or equal to 0.015 percent; s is less than or equal to 0.035%; cr: 0.15-0.30%; v: 0.10-0.15%; al: 0.01-0.05%; nb is less than or equal to 0.045%; ti: 0.015-0.035%; n: 0.01-0.02%; ni is less than or equal to 0.25 percent; mo is less than or equal to 0.10 percent; sn is less than or equal to 0.03 percent; cu is less than or equal to 0.20 percent; the balance of Fe and other inevitable impurities.
C: 0.43 to 0.47%, which determines important elements of the strength of the non-quenched and tempered steel. The strength of steel is ensured, carbon is the most effective element with low cost, and can be combined with strong carbide forming elements such as V, Ti, Nb, Mo and the like to form carbides to play roles of precipitation strengthening and fine grain strengthening, so that the steel strength is increased, recrystallization is prevented, and the recrystallization temperature is increased; the carbon content is increased to increase the volume fraction of pearlite, and as a result, the pearlite has higher strength but lower toughness, so that the content of C is limited to the range of 0.43-0.47% by comprehensively considering the cost and the steel performance.
Si: 0.50-0.80%, important elements for improving the toughness of non-quenched and tempered steel, and good effect on molten steel deoxidation. The content of Si in most microalloyed non-quenched and tempered steel is about 0.30 percent, the improvement of the content of Si can obviously strengthen ferrite by solid solution and promote the formation of ferrite, and is beneficial to improving the toughness, but when the content of Si is more than 0.90 percent, the fatigue strength of the steel is reduced, a banded structure is easily formed in the steel, and the transverse performance is lower than the longitudinal performance, so the content of Si is limited to 0.50 to 0.80 percent in comprehensive consideration.
Mn: 1.20-1.60%, and important alloy elements for improving the strength and toughness of non-quenched and tempered steel. The Mn element can also improve the solubility of VC and VN in austenite, is beneficial to the precipitation of VC and VN in ferrite, is beneficial to refining pearlite when the Mn content is more than 1.0 percent, reduces the interlamellar spacing of pearlite plates, reduces the thickness of cementite plates in pearlite, and improves the toughness of steel, but improves the volume fraction of pearlite of steel when the Mn content is more than or equal to 2 percent, and reduces the toughness, so the comprehensive consideration limits the Mn content to 1.20-1.60 percent.
S is less than or equal to 0.035%, the cutting performance is improved, sulfide formed by combining S and Mn has the effect of remarkably improving the cutting performance, the non-quenched and tempered steel is added with sulfur and is subjected to calcium or tellurium treatment to obtain a favorable shape and distribution of the sulfide, the sulfide is distributed in grains in a broken particle shape, and has certain plasticity during high-temperature forging (or hot rolling), so that the hot brittleness of forging (or hot rolling) forming can be avoided, and the forming is facilitated; after steel is formed by forging (or hot rolling), a microstructure forms a plurality of dimple structures, and when the steel is subsequently machined, the iron chips are broken off in a C shape when the cutter is cut in the region due to uneven stress, so that the phenomenon of early abrasion of the cutter caused by the fact that the iron chips are wound on the cutter is avoided, and the automatic machining chip removal function can be realized. Increasing the sulfur content can also increase the intergranular ferrite content so as to improve the toughness, and comprehensively considering the S content to be less than or equal to 0.035 percent according to the requirement of machinability.
Cr: 0.15-0.30%, and important alloy elements for improving the strength of the non-quenched and tempered steel, and simultaneously, the impact on the ductility and toughness is small.
V: 0.10-0.15%, and the non-quenched and tempered steel is the most effective strengthening element. Among three microalloying elements of Nb, V and Ti, V has higher solubility, and mainly plays roles of precipitation strengthening and fine grain strengthening by forming a fine precipitated phase in steel. V is a deoxidizer of steel, has great affinity with O and N, and is also a strong carbide element to form VC, the dispersity of VC in non-quenched and tempered steel is very high and stable, and the high dispersion distribution of VC can prevent coarse grains of a welding seam, so that the weldability of steel can be improved. However, when V is more than 0.3%, the temper brittleness of the steel increases, and the V content is limited to 0.10% to 0.15% in consideration of the above.
Al: 0.01-0.05%, adding proper Al into the molten steel to generate stable AlN and simulate the generation and precipitation of Fe4N, not only improving the timeliness of the steel, but also preventing the growth of austenite grains, fixing nitrogen in AlN, TiN or VN for precipitation strengthening after the nitrogen fixation of Al, Ti or V in the molten steel, and generally limiting the Al content to 0.01-0.05%.
Nb is less than or equal to 0.045%, the Nb element is added, and the low-temperature rolling of an austenite non-recrystallization region is beneficial to the large-amount dispersion precipitation of V (C, N) in a grain boundary and on dislocation, a large number of nucleation positions are provided for ferrite, uniform and fine pro-eutectoid ferrite can be obtained, non-quenched and tempered steel grains are refined, the strength is improved, the width of the non-recrystallization region is increased, and the rolling manufacturability is improved, wherein Nb (C, N) can pin the grain boundary during steel rolling, and solid-solution Nb is much larger than Fe due to the atomic radius ratio, the enrichment concentration of the solid-solution Nb in the grain boundary can reach more than 1% (atomic ratio), the solid solution Nb is lower in the grain, the Nb has strong capability of dragging the grain boundary to move, and the two functions enable Nb to have the effect of preventing the grains from growing up. The Nb-V-Ti composite micro-alloying can promote Nb (C, N) to be precipitated and pin a grain boundary, and the recrystallization of austenite in the planned finish rolling or finish forging process can be promoted, so that the recrystallization termination temperature of the austenite can be raised to 950 ℃, the transformation temperature of the austenite to ferrite is lowered, and the grain refinement of the proeutectoid ferrite is facilitated. The Nb-V-Ti microalloyed non-quenched and tempered steel is subjected to low-temperature rolling or forging (the deformation rate is more than 20%) in an austenite non-recrystallization region at 850-900 ℃, so that the interlayer spacing of pearlite can be reduced to 50-100nm, and the thickness of a cementite layer can be reduced to 30-100nm, thereby remarkably improving the high strength and high toughness of the non-quenched and tempered steel. The Nb-V-Ti composite microalloyed non-quenched and tempered steel does not recrystallize between hot processing passes of 900-1100 ℃, austenite grains can reach high deformation to form a thin discus shape by accumulating deformation, a large amount of crystal interfaces are provided for alpha nucleation during gamma → alpha transition in a controlled cooling stage after rolling, the grain size of ferrite after phase transition is improved by improving the non-recrystallization deformation of gamma grains, and the toughness of the non-quenched and tempered steel is improved. The content of Nb is limited to less than or equal to 0.045 percent by comprehensive consideration.
Ti: 0.015% -0.035%, one of the important microalloying elements of the non-quenched and tempered steel, in Nb, V, Ti microalloying carbonitride, TiN is most stable and most effective for controlling austenite grain growth, when the nitrogen content reaches 150-200ppm, Ti in the steel: n is close to or lower than 1: 1, the coarsening temperature of TiN for effectively controlling the growth of crystal grains can be increased to more than 1300 ℃. The nitrogen increase in the steel reduces the dissolution of TiN particles in high-temperature austenite, and hinders the growth process of the TiN particles through an Ostald curing mechanism, so that the stability of the TiN particles is improved. However, the content of Ti is not too high, otherwise, TiN particles are coarse, which not only can not prevent the growth of crystal grains, but also can damage the cutting processing performance and the fatigue life of the steel, and the content of Ti is comprehensively considered to be limited to 0.015-0.035%.
N: 0.010% -0.020% of economically effective microalloying elements in non-quenched and tempered steel, the smelting of the non-quenched and tempered steel promotes a large amount of VN particles to be precipitated through nitrogen increasing treatment (compared with carbon, nitrogen has stronger affinity with vanadium, and nitride is more stable), austenite grains can be effectively refined, the precipitation of intragranular ferrite (IGF) is promoted, coarse pearlite groups are effectively segmented, the impact toughness of the non-quenched and tempered steel is improved, the precipitation of V (C, N) in the steel can be promoted, austenite-ferrite grain boundaries are effectively pinned, and ferrite tissues are refined. For the micro-titanium processed non-quenched and tempered steel, the nitrogen is added, the stability of TiN particles is improved, the austenite grains are prevented from growing, cheap and rich nitrogen is fully utilized, the precious metal vanadium alloy can be saved, and the cost of the non-quenched and tempered steel is reduced. The economical and reliable nitrogen increasing method in vanadium-containing non-quenched and tempered steel adopts vanadium-nitrogen alloy (Nitrivan) additive developed by vanadium corporation in America: the vanadium-nitrogen alloy Nitrovan is an economic and effective additive for non-quenched and tempered steel, and comprises 80% of V, 12% of N, 16% of N, 8% of C and 4% of C, the method is convenient to add, the recovery rate of vanadium and nitrogen is high, the recovery rate of vanadium and nitrogen generally reaches 95%, the recovery rate of nitrogen reaches 70%, and by applying Nitrovan12, 10ppm of nitrogen can be brought into steel by increasing V by 0.01%.
Ni: not more than 0.25 percent, improves the strength of the steel, reduces important alloy elements of the low-temperature brittleness of the steel, can strengthen ferrite, reduce the carbon content of eutectoid pearlite, refine and increase the pearlite, improve the fatigue strength of the steel and reduce the notch sensitivity of the steel, and compared with other alloy elements, the Ni has higher relative cost, thereby comprehensively considering the performance and cost factors of the steel, and limiting the Ni content to not more than 0.25 percent.
Mo: not more than 0.10 percent, refined crystal grains and improved strength of the non-quenched and tempered steel, and the combination of Mo and Cr can greatly improve the hardenability of the non-quenched and tempered steel and also improve the impact toughness of the steel. However, when Mo is more than 0.1%, a ferrite phase or other brittle phases are likely to appear to reduce the toughness of the non-quenched and tempered steel, and the Mo content is limited to less than or equal to 0.1% in comprehensive consideration.
Cu: the corrosion resistance of the steel is improved by less than or equal to 0.20 percent, the strength of the steel can be improved by adding Cu into non-quenched and tempered steel, but when the Cu content is more than 0.2 percent, the phenomenon of copper brittleness is easy to generate, forging cracks are easy to generate in the high-temperature forging process, and the relative cost of Cu is higher compared with other alloy elements, so the Cu content is limited to less than or equal to 0.20 percent by comprehensively considering the performance and cost factors of the steel.
Further, the metallurgical structure of the non-quenched and tempered steel is pearlite + ferrite + martensite or pearlite + ferrite + bainite.
Furthermore, the volume percentage content of ferrite is 5-25%, the average grain size of austenite grain size is 7-9 grades, the pearlite is in a fine pearlite form, and the lamellar spacing of the pearlite is less than or equal to 200 nm.
Further, the volume percentage of bainite is less than 5%.
Further, the surface structure of the non-heat treated steel is acicular martensite + flaky martensite.
Further, the internal matrix structure of the non-quenched and tempered steel is lamellar pearlite + discontinuous network ferrite.
Another object of the present invention is to provide a method for producing the above non-heat-treated steel, comprising the steps of:
steel making: the non-quenched and tempered steel is subjected to converter steelmaking → ladle refining → ladle vacuum degassing → continuous casting → controlled rolling and controlled cooling to prepare round steel;
blanking: sawing the round steel into a bar stock with a lower specification by a common sawing machine;
machining: processing the specification bar stock to a knuckle pin with specification and size by using a common lathe;
surface induction quenching and tempering: carrying out surface induction quenching and tempering treatment on the knuckle pin manufactured in the step, wherein the induction quenching adopts a supersonic frequency scanning quenching mode;
grinding the excircle: grinding the knuckle pin manufactured in the step to the size required by the drawing through a numerical control cylindrical grinder;
flaw detection: and (4) carrying out 100% red magnetic powder inspection on the steering knuckle pin manufactured in the step, and carrying out demagnetization on a crack-free piece.
Furthermore, the machining allowance is 0.4-0.6mm, compared with the traditional quenched and tempered steel, the machining allowance is reduced (the machining allowance of the traditional quenched and tempered steel is 2mm), the production efficiency is improved by more than 40%, and meanwhile, because the non-quenched and tempered steel contains S element, the cutting machining performance is improved, and the tool consumption cost is reduced by more than 20%.
Further, the surface induction quenching process parameters are as follows: the voltage is 300V-450V, the current is 100A-150A, the frequency is 15KHz-30KHz, the gap between the inductor and the workpiece is 2mm-2.5mm, the moving speed of the inductor is 550mm/min-680mm/min, the concentration of quenching liquid AQ is 2% -4%, the temperature is 20 ℃ -40 ℃, the pressure is 0.2MPa-0.3MPa, the quenching heating temperature is controlled to be 900 +/-20 ℃, the shaft diameter surface hardness is 60-63HRC, the distance from the shaft diameter surface is 1-1.6mm, and the hardness is not lower than 575 HV.
Accordingly, the present invention also provides an application using the knuckle pin made of the non-quenched and tempered steel as described above; the knuckle pin manufactured by the invention improves the cutting processing performance and the wear resistance of the knuckle pin, and is suitable for manufacturing related parts in the field of automobiles.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention discloses non-quenched and tempered steel, wherein the tensile strength Rm is 900-1150MPa, the yield strength Rel is more than or equal to 600MPa, the elongation A is more than or equal to 10%, the reduction of area Z is more than or equal to 20%, the impact energy AKu is more than or equal to 30J, and the hardness 276-278 HB; the mass percentage content range of chemical elements of the non-quenched and tempered steel is as follows: c: 0.43 to 0.47 percent; si: 0.50-0.80%; mn: 1.20-1.60%; p is less than or equal to 0.015 percent; s is less than or equal to 0.035%; cr: 0.15-0.30%; v: 0.10-0.15%; al: 0.01-0.05%; nb is less than or equal to 0.045%; ti: 0.015-0.035%; n: 0.01-0.02%; ni is less than or equal to 0.25 percent; mo is less than or equal to 0.10 percent; sn is less than or equal to 0.03 percent; cu is less than or equal to 0.20 percent; the balance of Fe and other inevitable impurities, the manufacturing method of the quenched and tempered steel comprises steel making, blanking, machining, surface induction quenching, tempering, external circle grinding and flaw detection, the non-quenched and tempered steel manufactured by the method has excellent mechanical properties, the traditional quenching and tempering heat treatment process is omitted, the machining allowance is reduced, the production efficiency is improved, and the cutting processability and the wear resistance of the knuckle pin manufactured by the non-quenched and tempered steel are improved.
Drawings
FIG. 1 is a schematic view of a heavy duty car knuckle pin made of non-quenched and tempered steel at 400X of a metallographic structure of 0.5mm in example 1 of the invention.
FIG. 2 is a schematic view of a heavy duty car knuckle pin made of non-quenched and tempered steel at a position of 1mm at 400X in metallographic structure in example 1 of the present invention.
FIG. 3 is a schematic view of a heavy duty car knuckle pin made of non-quenched and tempered steel at 400X of a 1.6mm metallographic structure in example 1 of the present invention.
FIG. 4 is a schematic view of a heavy duty car knuckle pin made of non-quenched and tempered steel at 400X of a metallographic structure 2mm in example 1 of the present invention.
Detailed Description
The present invention will now be described in further detail with reference to the attached drawings, which are illustrative, but not limiting, of the present invention.
The non-quenched and tempered steel has tensile strength Rm of 900-1150MPa, yield strength Rel of more than or equal to 600MPa, elongation A of more than or equal to 10 percent, reduction of area Z of more than or equal to 20 percent and impact energy AKu of more than or equal to 30J; the non-quenched and tempered steel comprises the following chemical elements in percentage by mass: c: 0.43 to 0.47 percent; si: 0.50-0.80%; mn: 1.20-1.60%; p is less than or equal to 0.015 percent; s is less than or equal to 0.035%; cr: 0.15-0.30%; v: 0.10-0.15%; al: 0.01-0.05%; nb is less than or equal to 0.045%; ti: 0.015-0.035%; n: 0.01-0.02%; ni is less than or equal to 0.25 percent; mo is less than or equal to 0.10 percent; sn is less than or equal to 0.03 percent; cu is less than or equal to 0.20 percent; the balance of Fe and other inevitable impurities.
The metallographic structure of the non-quenched and tempered steel is pearlite, ferrite, martensite or bainite.
The volume percentage content of ferrite is 5-25%, the average grain size of austenite grain size is 7-9 grades, the pearlite is in a fine pearlite form, and the lamellar spacing of the pearlite is less than or equal to 200 nm.
The volume percentage of the bainite is less than 5%.
The surface structure of the non-quenched and tempered steel is acicular martensite + flaky martensite.
The internal matrix structure of the non-quenched and tempered steel is lamellar pearlite and discontinuous net ferrite.
The method comprises the following steps:
steel making: the non-quenched and tempered steel is subjected to converter steelmaking → ladle refining → ladle vacuum degassing → continuous casting → controlled rolling and controlled cooling to prepare round steel;
blanking: sawing the round steel into a bar stock with a lower specification by a common sawing machine;
machining: processing the specification bar stock to a knuckle pin with specification and size by using a common lathe;
surface induction quenching and tempering: carrying out surface induction quenching and tempering treatment on the knuckle pin manufactured in the step, wherein the induction quenching adopts a supersonic frequency scanning quenching mode;
grinding the excircle: grinding the knuckle pin manufactured in the step to the size required by the drawing through a numerical control cylindrical grinder;
flaw detection: and (4) carrying out 100% red magnetic powder inspection on the steering knuckle pin manufactured in the step, and carrying out demagnetization on a crack-free piece.
The machining allowance is 0.4-0.6mm, compared with the traditional quenched and tempered steel, the machining allowance is reduced (the machining allowance of the traditional quenched and tempered steel is 2mm), the production efficiency is improved by more than 40%, and meanwhile, because the non-quenched and tempered steel contains S elements, the cutting machining performance is improved, and the consumption cost of a cutter is reduced by more than 20%.
The parameters of the surface induction quenching process are as follows: the voltage is 300V-450V, the current is 100A-150A, the frequency is 15KHz-30KHz, the gap between the inductor and the workpiece is 2mm-2.5mm, the moving speed of the inductor is 550mm/min-680mm/min, the concentration of quenching liquid AQ is 2% -4%, the temperature is 20 ℃ -40 ℃, the pressure is 0.2MPa-0.3MPa, the quenching heating temperature is controlled to be 900 +/-20 ℃, the shaft diameter surface hardness is 60-63HRC, the distance from the shaft diameter surface is 1-1.6mm, and the hardness is not lower than 575 HV.
Accordingly, the present invention also provides a knuckle pin made of the non-quenched and tempered steel as described above; the knuckle pin provided by the invention improves the cutting processing performance and the wear resistance of the knuckle pin, and is suitable for manufacturing related parts in the field of automobiles.
Example 1:
1. steel making;
the non-quenched and tempered steel is prepared into round steel through converter steelmaking → ladle refining → ladle vacuum degassing → continuous casting → controlled rolling and controlled cooling, and the mass percentage of chemical elements is as follows: c: 0.43; si: 0.5; mn: 1.2; p: 0.008; s: 0.021; cr: 0.15; v: 0.1; al: 0.01; nb: 0.035; ti: 0.015, Ni: 0.01; mo: 0.006; sn: 0.001; cu: 0.08, and the balance of Fe and other inevitable impurities.
Gas content [ N ]: 172ppm, [ O ]: 13ppm, [ H ]: 1.2 ppm;
2. blanking:
and sawing the round steel into a bar stock with a lower specification by using a common sawing machine.
3. Machining:
and machining the specification bar stock to the knuckle pin with the specification size by using a common lathe.
4. Surface induction quenching and tempering:
and carrying out surface induction quenching and tempering treatment on the knuckle pin manufactured in the step, wherein the induction quenching adopts a supersonic frequency scanning quenching mode.
5. Grinding external circle
And grinding the knuckle pin manufactured in the step to the size required by the drawing through a numerical control cylindrical grinding machine.
6. Flaw detection
And (4) carrying out 100% red magnetic powder inspection on the steering knuckle pin manufactured in the step, and carrying out demagnetization on a crack-free piece.
Detecting the mechanical property of a hot rolled material: tensile strength, yield strength, elongation, reduction of area, impact work, and hardness are shown in Table 1.
Table 1: hot rolled mechanical property meter for non-quenched and tempered steel raw material
Performing physical and chemical analysis on the non-quenched and tempered steel heavy-duty car knuckle pin manufactured in the step 1-5: the hardness was measured at a distance of 0.5mm, 1.0mm, 1.6mm, 2.0mm, 3.0mm, 5.0mm, 9.0mm from the surface of the non-quenched and tempered steel, and the data thereof are statistically shown in Table 2.
Table 2: surface induction quenching effective hardened layer hardness meter for non-quenched and tempered steel knuckle pin
| Distance surface/mm | 0.5 | 1.0 | 1.6 | 2.0 | 3.0 | 5.0 | 9.0 |
| hardness/HRC | 63.0 | 58.2 | 55.9 | 31.2 | 29.9 | 28.1 | 26.5 |
Example 2:
1. steel making;
the non-quenched and tempered steel is prepared into round steel through converter steelmaking → ladle refining → ladle vacuum degassing → continuous casting → controlled rolling and controlled cooling, and the mass percentage of chemical elements is as follows: c: 0.45 of; si: 0.74 of; mn: 1.45 of; p: 0.01; s: 0.03; cr: 0.27; v: 0.13; al: 0.03; nb: 0.03; ti: 0.018, Ni: 0.015; mo: 0.05; sn: 0.008; cu: 0.12, and the balance of Fe and other inevitable impurities.
Gas content [ N ]: 172ppm, [ O ]: 13ppm, [ H ]: 1.2 ppm;
2. blanking:
and sawing the round steel into a bar stock with a lower specification by using a common sawing machine.
3. Machining:
and machining the specification bar stock to the knuckle pin with the specification size by using a common lathe.
4. Surface induction quenching and tempering:
and carrying out surface induction quenching and tempering treatment on the knuckle pin manufactured in the step, wherein the induction quenching adopts a supersonic frequency scanning quenching mode.
5. Grinding external circle
And grinding the knuckle pin manufactured in the step to the size required by the drawing through a numerical control cylindrical grinding machine.
6. Flaw detection
And (4) carrying out 100% red magnetic powder inspection on the steering knuckle pin manufactured in the step, and carrying out demagnetization on a crack-free piece.
Detecting the mechanical property of a hot rolled material: tensile strength, yield strength, elongation, reduction of area, impact work, and hardness are shown in Table 3.
Table 3: hot rolled mechanical property meter for non-quenched and tempered steel raw material
Performing physical and chemical analysis on the non-quenched and tempered steel heavy-duty car knuckle pin manufactured in the step 1-5: the hardness was measured at a distance of 0.5mm, 1.0mm, 1.6mm, 2.0mm, 3.0mm, 5.0mm, 9.0mm from the surface of the non-quenched and tempered steel, and the data thereof are statistically shown in Table 4.
Table 4: surface induction quenching effective hardened layer hardness meter for non-quenched and tempered steel knuckle pin
| Distance surface/mm | 0.5 | 1.0 | 1.6 | 2.0 | 3.0 | 5.0 | 9.0 |
| hardness/HRC | 63.2 | 58.4 | 56.0 | 31.5 | 30.1 | 28.3 | 26.6 |
Example 3:
1. steel making;
the non-quenched and tempered steel is prepared into round steel through converter steelmaking → ladle refining → ladle vacuum degassing → continuous casting → controlled rolling and controlled cooling, and the mass percentage of chemical elements is as follows: c: 0.47; si: 0.8; mn: 1.6; p: 0.015; s: 0.035; cr: 0.3; v: 0.15; al: 0.05; nb: 0.045; ti: 0.035, Ni: 0.025; mo: 0.1; sn: 0.03; cu: 0.2, and the balance of Fe and other inevitable impurities.
Gas content [ N ]: 172ppm, [ O ]: 13ppm, [ H ]: 1.2 ppm;
2. blanking:
and sawing the round steel into a bar stock with a lower specification by using a common sawing machine.
3. Machining:
and machining the specification bar stock to the knuckle pin with the specification size by using a common lathe.
4. Surface induction quenching and tempering:
and carrying out surface induction quenching and tempering treatment on the knuckle pin manufactured in the step, wherein the induction quenching adopts a supersonic frequency scanning quenching mode.
5. Grinding external circle
And grinding the knuckle pin manufactured in the step to the size required by the drawing through a numerical control cylindrical grinding machine.
6. Flaw detection
And (4) carrying out 100% red magnetic powder inspection on the steering knuckle pin manufactured in the step, and carrying out demagnetization on a crack-free piece.
Detecting the mechanical property of a hot rolled material: tensile strength, yield strength, elongation, reduction of area, impact work, and hardness are shown in Table 5.
Table 5: hot rolled mechanical property meter for non-quenched and tempered steel raw material
Performing physical and chemical analysis on the non-quenched and tempered steel heavy-duty car knuckle pin manufactured in the step 1-5: the hardness was measured at a distance of 0.5mm, 1.0mm, 1.6mm, 2.0mm, 3.0mm, 5.0mm, 9.0mm from the surface of the non-quenched and tempered steel, and the data thereof are statistically shown in Table 6.
Table 6: surface induction quenching effective hardened layer hardness meter for non-quenched and tempered steel knuckle pin
| Distance surface/mm | 0.5 | 1.0 | 1.6 | 2.0 | 3.0 | 5.0 | 9.0 |
| hardness/HRC | 62.6 | 58.1 | 55.5 | 30.8 | 29.6 | 28.0 | 26.1 |
Comparative example:
1. steel making;
the non-quenched and tempered steel is prepared into round steel through converter steelmaking → ladle refining → ladle vacuum degassing → continuous casting → controlled rolling and controlled cooling, and the mass percentage of chemical elements is as follows: c: 0.48; si: 0.82; mn: 1.65; p: 0.04; s: 0.036; cr: 0.31; v: 0.17; al: 0.06; nb: 0.05; ti: 0.04, Ni: 0.3; mo: 0.12; sn: 0.04; cu: 0.25 and the balance of Fe and other inevitable impurities.
Gas content [ N ]: 172ppm, [ O ]: 13ppm, [ H ]: 1.2 ppm;
2. blanking:
and sawing the round steel into a bar stock with a lower specification by using a common sawing machine.
3. Machining:
and machining the specification bar stock to the knuckle pin with the specification size by using a common lathe.
4. Surface induction quenching and tempering:
and carrying out surface induction quenching and tempering treatment on the knuckle pin manufactured in the step, wherein the induction quenching adopts a supersonic frequency scanning quenching mode.
5. Grinding external circle
And grinding the knuckle pin manufactured in the step to the size required by the drawing through a numerical control cylindrical grinding machine.
6. Flaw detection
And (4) carrying out 100% red magnetic powder inspection on the steering knuckle pin manufactured in the step, and carrying out demagnetization on a crack-free piece.
Detecting the mechanical property of a hot rolled material: tensile strength, yield strength, elongation, reduction of area, impact work, and hardness are shown in Table 7.
Table 7: hot rolled mechanical property meter for non-quenched and tempered steel raw material
Performing physical and chemical analysis on the non-quenched and tempered steel heavy-duty car knuckle pin manufactured in the step 1-5: the hardness was measured at a distance of 0.5mm, 1.0mm, 1.6mm, 2.0mm, 3.0mm, 5.0mm, 9.0mm from the surface of the non-quenched and tempered steel, and the data thereof are statistically shown in Table 8.
Table 8: surface induction quenching effective hardened layer hardness meter for non-quenched and tempered steel knuckle pin
| Distance surface/mm | 0.5 | 1.0 | 1.6 | 2.0 | 3.0 | 5.0 | 9.0 |
| hardness/HRC | 61.6 | 57.6 | 55.8 | 30.3 | 29.1 | 27.6 | 26.0 |
As can be seen from Table 9, although the hot-rolled mechanical properties of the comparative examples are comparable in elongation, reduction of area, work of impact and hardness, but the tensile strength and yield strength are greatly different from those of the examples, the tensile strength is only 850 and the yield strength is only 560, such parameters indicate that the non-heat-treated steel of the comparative examples is poor in high toughness and the workability after processing into a knuckle pin is not good as compared with the knuckle pin made of the non-heat-treated steel of the examples, while the data of the reaction in Table 10 indicate that the surface hardness of the comparative examples is poor and the wear resistance of the knuckle pin made of the non-heat-treated steel of the examples is good.
TABLE 9
Watch 10
The embodiments given above are preferable examples for implementing the present invention, and the present invention is not limited to the above-described embodiments. Any non-essential addition and replacement made by the technical characteristics of the technical scheme of the invention by a person skilled in the art belong to the protection scope of the invention.
Claims (10)
1. A non-quenched and tempered steel is characterized in that the tensile strength Rm is 900-1150MPa, the yield strength Rel is more than or equal to 600MPa, the elongation A is more than or equal to 10%, the reduction of area Z is more than or equal to 20%, and the impact energy AKu is more than or equal to 30J; the non-quenched and tempered steel comprises the following chemical elements in percentage by mass: c: 0.43 to 0.47 percent; si: 0.50-0.80%; mn: 1.20-1.60%; p is less than or equal to 0.015 percent; s is less than or equal to 0.035%; cr: 0.15-0.30%; v: 0.10-0.15%; al: 0.01-0.05%; nb is less than or equal to 0.045%; ti: 0.015-0.035%; n: 0.01-0.02%; ni is less than or equal to 0.25 percent; mo is less than or equal to 0.10 percent; sn is less than or equal to 0.03 percent; cu is less than or equal to 0.20 percent; the balance of Fe and other inevitable impurities.
2. A non heat-treated steel according to claim 1, wherein said non heat-treated steel has a metallographic structure of pearlite + ferrite + martensite or pearlite + ferrite + bainite.
3. The non-quenched and tempered steel of claim 2, wherein the ferrite is 5 to 25 volume percent, the austenite grain size average grain size is 7 to 9 grades, the pearlite is in the form of fine pearlite, and the pearlite interlamellar spacing is not more than 200 nm.
4. A non-heat-treated steel according to claim 2, characterised in that the bainite is less than 5% by volume.
5. The non heat treated steel according to claim 1, wherein the surface structure of the non heat treated steel is acicular martensite + flaky martensite.
6. The non heat-treated steel according to claim 1, wherein the internal matrix structure of the non heat-treated steel is lamellar pearlite + discontinuous network ferrite.
7. The method of manufacturing a non heat-treated steel as set forth in any one of claims 1 to 6, characterized by comprising the steps of:
steel making: the non-quenched and tempered steel is subjected to converter steelmaking → ladle refining → ladle vacuum degassing → continuous casting → controlled rolling and controlled cooling to prepare round steel;
blanking: sawing the round steel into a bar stock with a lower specification by a common sawing machine;
machining: processing the specification bar stock to a knuckle pin with specification and size by using a common lathe;
surface induction quenching and tempering: carrying out surface induction quenching and tempering treatment on the knuckle pin manufactured in the step, wherein the induction quenching adopts a supersonic frequency scanning quenching mode;
grinding the excircle: grinding the knuckle pin manufactured in the step to the size required by the drawing through a numerical control cylindrical grinder;
flaw detection: and (4) carrying out 100% red magnetic powder inspection on the steering knuckle pin manufactured in the step, and carrying out demagnetization on a crack-free piece.
8. A method of manufacturing a non heat-treated steel as defined in claim 7, wherein said machining allowance is 0.4 to 0.6 mm.
9. The method of manufacturing a non-quenched and tempered steel as recited in claim 7, wherein the surface induction hardening process parameters are: the voltage is 300V-450V, the current is 100A-150A, the frequency is 15KHz-30KHz, the gap between the inductor and the workpiece is 2mm-2.5mm, the moving speed of the inductor is 550mm/min-680mm/min, the concentration of quenching liquid AQ is 2% -4%, the temperature is 20 ℃ -40 ℃, the pressure is 0.2MPa-0.3MPa, the quenching heating temperature is controlled to be 900 +/-20 ℃, the shaft diameter surface hardness is 60-63HRC, the distance from the shaft diameter surface is 1-1.6mm, and the hardness is not lower than 575 HV.
10. Use of the non heat treated steel according to any one of claims 1 to 6 for the production of a knuckle pin.
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