Anti-fatigue die steel and production method thereof

Abstract

The invention provides anti-fatigue die steel and a production method thereof, and relates to the technical field of die steel, and the anti-fatigue die steel comprises the following components: C, Si, Cu, Nb, Cr, Ta, rare earth elements, Te, B, Ir, Ge, Co, Ba, Hf, nano titanium nitride, nano molybdenum disilicide and Fe. The anti-fatigue die steel is good in mechanical property, sufficient in toughness, good in anti-fatigue performance and wear resistance and excellent in corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of die steel, and in particular to an anti-fatigue die steel and a production method thereof. Background Art

[0002] Molds are the main processing tools for manufacturing parts in industrial sectors such as machinery manufacturing, radio instruments, motors, and electrical appliances. The quality of molds directly affects the quality of pressure processing technology, the precision output of products, and production costs. In addition to reasonable structural design and processing accuracy, the quality and service life of molds are mainly affected by mold materials and heat treatment. As a common mold material, mold steel is widely used in the manufacture of cold stamping molds, hot forging molds, die-casting molds, and other molds. With the development of science and technology and the progress of society, the demand for mold steel is getting greater and greater, and the performance requirements are getting higher and higher.

[0003] Mold steel will be subjected to huge impact loads in the working environment. Repeated heating and cooling will cause uneven thermal stress and thermal strain. At the same time, it will be subjected to friction between the flowing hot metal and the cavity surface. Therefore, its service life is short and it often fails due to cracking, collapse, wear, thermal fatigue, etc. In addition, the mold steel on the market still has more or less technical defects such as limited mechanical properties, high temperature wear resistance, corrosion resistance and impact toughness still need to be further improved.

[0004] In order to solve the above technical problems, a Chinese invention patent with authorization announcement number CN111057933B discloses a manufacturing process for hot working die steel for high-performance die casting molds, which relates to the field of die steel technology. The manufacturing process for hot working die steel includes the following steps: (1) smelting; (2) high temperature homogenization treatment; (3) forging; (4) annealing treatment; (5) tempering treatment; (6) nitriding treatment; and (7) tempering treatment. The hot working die steel is composed of the following components in weight percentage: C: 0.33-0.46%, Si: 1.5-2.3%, Mn: 0.32-0.45%, Mo: 1.6-2.3%, W: 2.6-3.6%, Nb: 0.16-0.27%, Cr: 2.8-3.7%, Sr: 0.21-0.53%, Ti: 0.16-0.31%, Ce: 0.05-0.09%, S≤0.003%, P≤0.03%, and the balance is Fe. The hot working die steel prepared by the invention has high surface hardness and wear resistance, good impact toughness, excellent fatigue resistance and strength, and effectively prolongs the service life of the hot working die steel for die casting molds. However, its corrosion resistance still needs to be further improved.

[0005] It can be seen that the development of an anti-fatigue mold steel with good mechanical properties, sufficient toughness, good fatigue resistance and wear resistance, and excellent corrosion resistance and its production method meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the mold steel field. Summary of the invention

[0006] The main purpose of the present invention is to provide an anti-fatigue die steel with good mechanical properties, sufficient toughness, good fatigue resistance and wear resistance, and excellent corrosion resistance, and a production method thereof.

[0007] To achieve the above purpose, the present invention provides an anti-fatigue die steel, which is composed of the following components in weight percentage: C: 0.2-0.4wt%, Si: 0.25-0.65wt%, Cu: 0.4-0.5wt%, Nb: 0.2-0.3wt%, Cr: 3-8wt%, Ta: 0.01-0.05wt%, rare earth elements: 0.1-0.3wt%, Te: 0.001-0.003wt%, B: 0.001-0.003wt%, Ir: 0.01-0.03wt%, Ge: 0.001-0.01wt%, Co: 0.1-0.3wt%, Ba: 0.001-0.003wt%, Hf: 0.01-0.04wt%, nano titanium nitride: 0.01-0.03wt%, nano molybdenum disilicide: 0.01-0.03wt%, and the balance is Fe.

[0008] Preferably, the rare earth elements are Sc, Y, Pr, and Tb mixed in a mass ratio of 1:(1-3):2:(0.3-0.5).

[0009] Preferably, the particle size of the nano titanium nitride is 10-80 nm; the particle size of the nano molybdenum disilicide is 20-90 nm.

[0010] Another object of the present invention is to provide a method for producing the fatigue-resistant die steel, comprising the following steps: Step S1, using pure iron, C-Fe master alloy, Si-Fe master alloy, Cu-Fe master alloy, Nb-Fe master alloy, Cr-Fe master alloy, Ta-Fe master alloy, rare earth element-Fe master alloy, Te-Fe master alloy, B-Fe master alloy, Ir-Fe master alloy, Ge-Fe master alloy, Co-Fe master alloy, Ba-Fe master alloy, Hf-Fe master alloy as raw materials, adopting a double vacuum process of vacuum induction and vacuum consumable remelting to melt into an alloy melt; then adding nano titanium nitride and nano molybdenum disilicide preheated at 550-650° C. to the above alloy melt, and after multi-energy field treatment, tapping and pouring to obtain a steel ingot; Step S2, subjecting the steel ingot obtained in step S1 to homogenization treatment, forging and heat treatment in sequence to obtain fatigue-resistant die steel.

[0011] Preferably, the vacuum degree of the vacuum induction and vacuum consumable remelting in step S1 is 0.01-2.5 Pa, and the steel ingot smelting temperature is 1500-1600°C.

[0012] Preferably, the pouring temperature of the steel ingot in step S1 is 1450-1530°C.

[0013] Preferably, the multi-energy field treatment in step S1 includes ultrasonic treatment, microwave treatment and electromagnetic oscillation field treatment performed in sequence, the ultrasonic treatment has an ultrasonic frequency of 40-80KHZ, a power of 200-400W, and a time of 5-8min; the microwave treatment has a frequency of 2.0-2.5GHz, a power of 700-1300W, and a time of 5-10min; the electromagnetic oscillation field treatment has a frequency of 15-30HZ, at which time the medium and low duty cycle is 15-25%, and the time is 3-5min.

[0014] Preferably, the temperature of the homogenization treatment in step S2 is 1250-1300° C., the holding time is 6-9 hours, and then air-cooled to room temperature.

[0015] Preferably, the starting forging temperature of the forging in step S2 is 1100-1140°C, and the final forging temperature is 860-890°C; after forging, it is mist-cooled to 400-450°C, and then placed in a heating furnace with an internal temperature of 360-430°C, kept warm for 25-40 minutes, and then cooled to room temperature with the furnace.

[0016] Preferably, the heat treatment in step S2 includes annealing and tempering.

[0017] Preferably, the annealing treatment temperature is 820-880° C., and the holding time is 1-3 hours.

[0018] Preferably, the tempering treatment temperature is 180-210° C., and the holding time is 1-2 h.

[0019] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The production method of anti-fatigue die steel disclosed in the present invention has simple process, convenient operation and control, high preparation efficiency and finished product qualification rate, low equipment dependence and energy consumption, is suitable for continuous large-scale production, and has high promotion and application value.

[0020] (2) The anti-fatigue die steel disclosed in the present invention is composed of the following components in weight percentage: C: 0.2-0.4wt%, Si: 0.25-0.65wt%, Cu: 0.4-0.5wt%, Nb: 0.2-0.3wt%, Cr: 3-8wt%, Ta: 0.01-0.05wt%, rare earth elements: 0.1-0.3wt%, Te: 0.001-0.003wt%, B: 0.001-0.003wt%, Ir: 0.01-0.03wt%, Ge: 0.001-0.01wt%, Co: 0.1-0.3wt%, Ba: 0.001-0.003wt%, Hf: 0.01-0.04wt%, nano titanium nitride: 0.01-0.03wt%, nano molybdenum disilicide: 0.01-0.03wt%, and the balance is Fe. Through the mutual coordination and joint action of various components, the mold steel products can be endowed with advantages such as good mechanical properties, sufficient toughness, good fatigue resistance and wear resistance, and excellent corrosion resistance.

[0021] (3) The anti-fatigue die steel disclosed in the present invention comprises rare earth elements Sc, Y, Pr and Tb mixed in a mass ratio of 1:(1-3):2:(0.3-0.5); the particle size of the nano titanium nitride is 10-80nm; the particle size of the nano molybdenum disilicide is 20-90nm; through the reasonable selection and limitation of the rare earth element composition and the particle sizes of nano titanium nitride and nano molybdenum disilicide, and the cooperation with other components, the mechanical properties, toughness, fatigue resistance, wear resistance and corrosion resistance of the die steel product can be further improved.

[0022] (4) The fatigue-resistant die steel disclosed in the present invention can effectively improve the performance (mechanical properties, toughness, fatigue resistance, wear resistance and corrosion resistance) and performance stability of the manufactured product through the reasonable selection of preparation process parameters, while also improving material utilization and productivity, thereby effectively extending the service life of the product. DETAILED DESCRIPTION

[0023] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0024] Example 1, a fatigue-resistant die steel, composed of the following components in weight percentage: C: 0.2wt%, Si: 0.25wt%, Cu: 0.4wt%, Nb: 0.2wt%, Cr: 3wt%, Ta: 0.01wt%, rare earth elements: 0.1wt%, Te: 0.001wt%, B: 0.001wt%, Ir: 0.01wt%, Ge: 0.001wt%, Co: 0.1wt%, Ba: 0.001wt%, Hf: 0.01wt%, nano-titanium nitride: 0.01wt%, nano-molybdenum disilicide: 0.01wt%, and the balance is Fe.

[0025] The rare earth elements are Sc, Y, Pr, and Tb mixed in a mass ratio of 1:1:2:0.3; the particle size of the nano titanium nitride is 10 nm; and the particle size of the nano molybdenum disilicide is 20 nm.

[0026] A method for producing the fatigue-resistant die steel comprises the following steps: Step S1, using pure iron, C-Fe master alloy, Si-Fe master alloy, Cu-Fe master alloy, Nb-Fe master alloy, Cr-Fe master alloy, Ta-Fe master alloy, rare earth element-Fe master alloy, Te-Fe master alloy, B-Fe master alloy, Ir-Fe master alloy, Ge-Fe master alloy, Co-Fe master alloy, Ba-Fe master alloy, Hf-Fe master alloy as raw materials, adopting a double vacuum process of vacuum induction and vacuum consumable remelting to melt into an alloy melt; then adding nano titanium nitride and nano molybdenum disilicide preheated at 550° C. to the above alloy melt, and after multi-energy field treatment, tapping and pouring to obtain a steel ingot; Step S2, subjecting the steel ingot obtained in step S1 to homogenization treatment, forging and heat treatment in sequence to obtain fatigue-resistant die steel.

[0027] The vacuum degree of the vacuum induction and vacuum consumable remelting in step S1 is 0.01 Pa, and the smelting temperature of the steel ingot is 1500° C.; the pouring temperature of the steel ingot in step S1 is 1450° C.

[0028] The multi-energy field treatment in step S1 includes ultrasonic treatment, microwave treatment and electromagnetic oscillation field treatment performed in sequence. The ultrasonic treatment has an ultrasonic frequency of 40KHZ, a power of 200W, and a time of 5 minutes; the microwave treatment has a frequency of 2.0GHz, a power of 700W, and a time of 5 minutes; the electromagnetic oscillation field treatment has a frequency of 15HZ, a medium and low duty cycle of 15%, and a time of 3 minutes.

[0029] The temperature of the homogenization treatment in step S2 is 1250°C, the holding time is 6 hours, and then air-cooled to room temperature; the start forging temperature of the forging in step S2 is 1100°C, and the final forging temperature is 860°C; after forging, it is mist-cooled to 400°C, and then placed in a heating furnace with an internal temperature of 360°C, and after holding for 25 minutes, it is cooled to room temperature with the furnace; the heat treatment in step S2 includes annealing and tempering; the temperature of the annealing treatment is 820°C, and the holding time is 1 hour; the temperature of the tempering treatment is 180°C, and the holding time is 1 hour.

[0030] Example 2, a fatigue-resistant die steel, composed of the following components in weight percentage: C: 0.25wt%, Si: 0.35wt%, Cu: 0.43wt%, Nb: 0.22wt%, Cr: 4wt%, Ta: 0.02wt%, rare earth elements: 0.15wt%, Te: 0.0015wt%, B: 0.0015wt%, Ir: 0.015wt%, Ge: 0.003wt%, Co: 0.15wt%, Ba: 0.0015wt%, Hf: 0.02wt%, nano-titanium nitride: 0.015wt%, nano-molybdenum disilicide: 0.015wt%, and the balance is Fe.

[0031] The rare earth elements are Sc, Y, Pr, and Tb mixed in a mass ratio of 1:1.5:2:0.35; the particle size of the nano titanium nitride is 30 nm; and the particle size of the nano molybdenum disilicide is 40 nm.

[0032] A method for producing the fatigue-resistant die steel comprises the following steps: Step S1, using pure iron, C-Fe master alloy, Si-Fe master alloy, Cu-Fe master alloy, Nb-Fe master alloy, Cr-Fe master alloy, Ta-Fe master alloy, rare earth element-Fe master alloy, Te-Fe master alloy, B-Fe master alloy, Ir-Fe master alloy, Ge-Fe master alloy, Co-Fe master alloy, Ba-Fe master alloy, Hf-Fe master alloy as raw materials, adopting a double vacuum process of vacuum induction and vacuum consumable remelting to melt into an alloy melt; then adding nano titanium nitride and nano molybdenum disilicide preheated at 580° C. to the above alloy melt, and after multi-energy field treatment, tapping and pouring to obtain a steel ingot; Step S2, subjecting the steel ingot obtained in step S1 to homogenization treatment, forging and heat treatment in sequence to obtain fatigue-resistant die steel.

[0033] The vacuum degree of the vacuum induction and vacuum consumable remelting in step S1 is 1Pa, and the smelting temperature of the steel ingot is 1530°C; the steel ingot pouring temperature in step S1 is 1480°C; the multi-energy field treatment in step S1 includes ultrasonic treatment, microwave treatment and electromagnetic oscillation field treatment performed in sequence, and the ultrasonic frequency of the ultrasonic treatment is 50KHZ, the power is 250W, and the time is 6min; the frequency of the microwave treatment is 2.2GHz, the power is 800W, and the time is 6min; the frequency of the electromagnetic oscillation field treatment is 20HZ, at this time the medium and low duty cycle is 18%, and the time is 3.5min.

[0034] The temperature of the homogenization treatment in step S2 is 1270°C, the holding time is 7h, and then air-cooled to room temperature; the start forging temperature of the forging in step S2 is 1110°C, and the final forging temperature is 870°C; after forging, it is mist-cooled to 420°C, and then placed in a heating furnace with an internal temperature of 380°C, and after holding for 30 minutes, it is cooled to room temperature with the furnace; the heat treatment in step S2 includes annealing and tempering; the temperature of the annealing treatment is 840°C, and the holding time is 1.5h; the temperature of the tempering treatment is 190°C, and the holding time is 1.2h.

[0035] Example 3, a fatigue-resistant die steel, composed of the following components in weight percentage: C: 0.3wt%, Si: 0.5wt%, Cu: 0.45wt%, Nb: 0.25wt%, Cr: 6wt%, Ta: 0.035wt%, rare earth elements: 0.2wt%, Te: 0.002wt%, B: 0.002wt%, Ir: 0.02wt%, Ge: 0.006wt%, Co: 0.2wt%, Ba: 0.002wt%, Hf: 0.025wt%, nano-titanium nitride: 0.02wt%, nano-molybdenum disilicide: 0.02wt%, and the balance is Fe.

[0036] The rare earth elements are Sc, Y, Pr, and Tb mixed in a mass ratio of 1:2:2:0.4; the particle size of the nano titanium nitride is 60nm; and the particle size of the nano molybdenum disilicide is 60nm.

[0037] A method for producing the fatigue-resistant die steel comprises the following steps: Step S1, using pure iron, C-Fe master alloy, Si-Fe master alloy, Cu-Fe master alloy, Nb-Fe master alloy, Cr-Fe master alloy, Ta-Fe master alloy, rare earth element-Fe master alloy, Te-Fe master alloy, B-Fe master alloy, Ir-Fe master alloy, Ge-Fe master alloy, Co-Fe master alloy, Ba-Fe master alloy, Hf-Fe master alloy as raw materials, adopting a double vacuum process of vacuum induction and vacuum consumable remelting to melt into an alloy melt; then adding nano titanium nitride and nano molybdenum disilicide preheated at 600° C. to the above alloy melt, and after multi-energy field treatment, tapping and pouring to obtain a steel ingot; Step S2, subjecting the steel ingot obtained in step S1 to homogenization treatment, forging and heat treatment in sequence to obtain fatigue-resistant die steel.

[0038] The vacuum degree of the vacuum induction and vacuum consumable remelting in step S1 is 1.5Pa, and the smelting temperature of the steel ingot is 1550°C; the steel ingot pouring temperature in step S1 is 1490°C; the multi-energy field treatment in step S1 includes ultrasonic treatment, microwave treatment and electromagnetic oscillation field treatment performed in sequence, and the ultrasonic frequency of the ultrasonic treatment is 60KHZ, the power is 300W, and the time is 6.5min; the frequency of the microwave treatment is 2.3GHz, the power is 900W, and the time is 7.5min; the frequency of the electromagnetic oscillation field treatment is 23HZ, at this time the medium and low duty cycle is 20%, and the time is 4min.

[0039] The temperature of the homogenization treatment in step S2 is 1280°C, the holding time is 7.5h, and then air-cooled to room temperature; the start forging temperature of the forging in step S2 is 1120°C, and the final forging temperature is 875°C; after forging, it is mist-cooled to 430°C, and then placed in a heating furnace with an internal temperature of 400°C, and after holding for 32 minutes, it is cooled to room temperature with the furnace; the heat treatment in step S2 includes annealing and tempering; the temperature of the annealing treatment is 850°C, and the holding time is 2h; the temperature of the tempering treatment is 195°C, and the holding time is 1.5h.

[0040] Example 4, a fatigue-resistant die steel, composed of the following components in weight percentage: C: 0.35wt%, Si: 0.6wt%, Cu: 0.48wt%, Nb: 0.27wt%, Cr: 7wt%, Ta: 0.04wt%, rare earth elements: 0.25wt%, Te: 0.0025wt%, B: 0.0025wt%, Ir: 0.025wt%, Ge: 0.008wt%, Co: 0.25wt%, Ba: 0.0025wt%, Hf: 0.035wt%, nano-titanium nitride: 0.025wt%, nano-molybdenum disilicide: 0.025wt%, and the balance is Fe.

[0041] The rare earth elements are Sc, Y, Pr, and Tb mixed in a mass ratio of 1:2.5:2:0.45; the particle size of the nano titanium nitride is 70nm; and the particle size of the nano molybdenum disilicide is 80nm.

[0042] A method for producing the fatigue-resistant die steel comprises the following steps: Step S1, using pure iron, C-Fe master alloy, Si-Fe master alloy, Cu-Fe master alloy, Nb-Fe master alloy, Cr-Fe master alloy, Ta-Fe master alloy, rare earth element-Fe master alloy, Te-Fe master alloy, B-Fe master alloy, Ir-Fe master alloy, Ge-Fe master alloy, Co-Fe master alloy, Ba-Fe master alloy, Hf-Fe master alloy as raw materials, adopting a double vacuum process of vacuum induction and vacuum consumable remelting to melt into an alloy melt; then adding nano titanium nitride and nano molybdenum disilicide preheated at 640° C. to the above alloy melt, and after multi-energy field treatment, tapping and pouring to obtain a steel ingot; Step S2, subjecting the steel ingot obtained in step S1 to homogenization treatment, forging and heat treatment in sequence to obtain fatigue-resistant die steel.

[0043] The vacuum degree of the vacuum induction and vacuum consumable remelting in step S1 is 2Pa, and the smelting temperature of the steel ingot is 1590°C; the steel ingot pouring temperature in step S1 is 1520°C; the multi-energy field treatment in step S1 includes ultrasonic treatment, microwave treatment and electromagnetic oscillation field treatment performed in sequence, and the ultrasonic frequency of the ultrasonic treatment is 75KHZ, the power is 350W, and the time is 7.5min; the frequency of the microwave treatment is 2.4GHz, the power is 1200W, and the time is 9min; the frequency of the electromagnetic oscillation field treatment is 28HZ, at this time the medium and low duty cycle is 23%, and the time is 4.5min.

[0044] The temperature of the homogenization treatment in step S2 is 1290°C, the holding time is 8.5h, and then air-cooled to room temperature; the start forging temperature of the forging in step S2 is 1135°C, and the final forging temperature is 885°C; after forging, it is mist-cooled to 440°C, and then placed in a heating furnace with an internal temperature of 420°C, and after holding for 38 minutes, it is cooled to room temperature with the furnace; the heat treatment in step S2 includes annealing and tempering; the temperature of the annealing treatment is 870°C, and the holding time is 2.5h; the temperature of the tempering treatment is 205°C, and the holding time is 1.8h.

[0045] Example 5, a fatigue-resistant die steel, composed of the following components in weight percentage: C: 0.4wt%, Si: 0.65wt%, Cu: 0.5wt%, Nb: 0.3wt%, Cr: 8wt%, Ta: 0.05wt%, rare earth elements: 0.3wt%, Te: 0.003wt%, B: 0.003wt%, Ir: 0.03wt%, Ge: 0.01wt%, Co: 0.3wt%, Ba: 0.003wt%, Hf: 0.04wt%, nano-titanium nitride: 0.03wt%, nano-molybdenum disilicide: 0.03wt%, and the balance is Fe.

[0046] The rare earth elements are Sc, Y, Pr, and Tb mixed in a mass ratio of 1:3:2:0.5; the particle size of the nano titanium nitride is 80nm; and the particle size of the nano molybdenum disilicide is 90nm.

[0047] A method for producing the fatigue-resistant die steel comprises the following steps: Step S1, using pure iron, C-Fe master alloy, Si-Fe master alloy, Cu-Fe master alloy, Nb-Fe master alloy, Cr-Fe master alloy, Ta-Fe master alloy, rare earth element-Fe master alloy, Te-Fe master alloy, B-Fe master alloy, Ir-Fe master alloy, Ge-Fe master alloy, Co-Fe master alloy, Ba-Fe master alloy, Hf-Fe master alloy as raw materials, adopting a double vacuum process of vacuum induction and vacuum consumable remelting to melt into an alloy melt; then adding nano titanium nitride and nano molybdenum disilicide preheated at 650° C. to the above alloy melt, and after multi-energy field treatment, tapping and pouring to obtain a steel ingot; Step S2, subjecting the steel ingot obtained in step S1 to homogenization treatment, forging and heat treatment in sequence to obtain fatigue-resistant die steel.

[0048] The vacuum degree of the vacuum induction and vacuum consumable remelting in step S1 is 2.5Pa, and the smelting temperature of the steel ingot is 1600℃; the steel ingot pouring temperature in step S1 is 1530℃; the multi-energy field treatment in step S1 includes ultrasonic treatment, microwave treatment and electromagnetic oscillation field treatment performed in sequence, and the ultrasonic frequency of the ultrasonic treatment is 80KHZ, the power is 400W, and the time is 8min; the frequency of the microwave treatment is 2.5GHz, the power is 1300W, and the time is 10min; the frequency of the electromagnetic oscillation field treatment is 30HZ, at this time the medium and low duty cycle is 25%, and the time is 5min.

[0049] The temperature of the homogenization treatment in step S2 is 1300°C, the holding time is 9h, and then air-cooled to room temperature; the start forging temperature of the forging in step S2 is 1140°C, and the final forging temperature is 890°C; after forging, it is mist-cooled to 450°C, and then placed in a heating furnace with an internal temperature of 430°C, and after holding for 40 minutes, it is cooled to room temperature with the furnace; the heat treatment in step S2 includes annealing and tempering; the temperature of the annealing treatment is 880°C, and the holding time is 3h; the temperature of the tempering treatment is 210°C, and the holding time is 2h.

[0050] Comparative Example 1 A fatigue-resistant die steel and a production method thereof, which are substantially the same as those of Example 1, except that Ta, Cu, Te and nano-titanium nitride are not added.

[0051] Comparative Example 2 A fatigue-resistant die steel and a production method thereof, which are substantially the same as those of Example 1, except that rare earth elements, Ir and nano-molybdenum disilicide are not added.

[0052] In order to further illustrate the beneficial technical effects of the anti-fatigue die steel involved in each embodiment of the present invention, relevant performance tests are performed on the anti-fatigue die steel involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1. The test method is as follows: (1) Tensile strength: The tensile strength of the sample is tested according to the national standard GB / T 228.1-2021; (2) Fatigue resistance: The specimens were subjected to equal-amplitude fatigue tests (maximum load 100 MPa, minimum load 20 MPa) on an Amsler HFP-422 high-frequency fatigue testing machine, and the fatigue life was recorded and counted.

[0053] (3) Corrosion resistance: The prepared anti-fatigue die steel was subjected to a salt spray corrosion test. The test temperature was 35°C, and a 5% mass concentration of sodium chloride aqueous solution was sprayed in the test chamber to simulate the accelerated corrosion of the environment. If the tolerance time (i.e., the time to remain rust-free) exceeded 1000h, the corrosion resistance passed, otherwise it failed.

[0054] (4) Wear resistance: A WTM-2E friction and wear tester was used, GCr15 ball bearing steel was used as the friction pair, the load was 100g, the friction diameter was 8mm, the rotation speed was 200r / min, and the time was 20min; before the experiment, the oxide scale on the surface to be ground was removed to expose the flat surface of the sample, the disc was rotated horizontally, and the sample was in vertical contact with the disc through the upper fixture, and the two rubbed and wore each other. The wear time was 20min to ensure that a stable wear state was achieved; the mass loss was measured using a Sartius Micr electronic balance, and the weight change of the sample during the wear process was studied, and the weight loss rate was calculated to measure the wear resistance of the material. The smaller the weight loss rate, the better the wear resistance.

[0055] (5) Impact toughness: The test is carried out in accordance with GB / T1817-2017. The value of the impact toughness of the test result is rounded to one decimal place.

[0056] Table 1

[0057] As can be seen from Table 1, the fatigue-resistant die steel disclosed in the embodiment of the present invention has better mechanical properties, fatigue resistance, impact toughness, corrosion resistance and wear resistance than the comparative product, and the combined addition of Ta, Cu, Te, rare earth elements, Ir, nano-molybdenum disilicide and nano-titanium nitride is beneficial to improving the above properties.

[0058] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A fatigue-resistant die steel, characterized in that: The following weight percentages of ingredients composition: C: 0.2-0.4wt%, Si: 0.25-0.65wt%, Cu: 0.4-0.5wt%, Nb: 0.2-0.3wt%, Cr: 3-8wt%, Ta: 0.01-0.05wt%, rare earth elements: 0.1-0.3wt%, Te: 0.001-0.003wt%, B: 0.001-0.003wt%, Ir: 0.01-0.03wt%, Ge: 0.001-0.01wt%, Co: 0.1-0.3wt%, Ba: 0.001-0.003wt%, Hf: 0.01-0.04wt%, nano titanium nitride: 0.01-0.03wt%, nano molybdenum disilicide: 0.01-0.03wt%, and the balance is Fe.

2. The anti-fatigue die steel according to claim 1, characterized in that: The rare earth elements are Sc, Y, Pr and Tb mixed in a mass ratio of 1:(1-3):2:(0.3-0.5).

3. The anti-fatigue die steel according to claim 1, characterized in that: The particle size of the nano titanium nitride is 10-80nm; the particle size of the nano molybdenum disilicide is 20-90nm.

4. A method for producing the fatigue-resistant die steel according to any one of claims 1 to 3, characterized in that: The steps include: Step S1, using pure iron, C-Fe master alloy, Si-Fe master alloy, Cu-Fe master alloy, Nb-Fe master alloy, Cr-Fe master alloy, Ta-Fe master alloy, rare earth element-Fe master alloy, Te-Fe master alloy, B-Fe master alloy, Ir-Fe master alloy, Ge-Fe master alloy, Co-Fe master alloy, Ba-Fe master alloy, Hf-Fe master alloy as raw materials, adopting a double vacuum process of vacuum induction and vacuum consumable remelting to melt into an alloy melt; then adding nano titanium nitride and nano molybdenum disilicide preheated at 550-650° C. to the above alloy melt, and after multi-energy field treatment, tapping and pouring to obtain a steel ingot; Step S2, subjecting the steel ingot obtained in step S1 to homogenization treatment, forging and heat treatment in sequence to obtain fatigue-resistant die steel.

5. The method for producing anti-fatigue die steel according to claim 4, characterized in that: The vacuum degree of the vacuum induction and vacuum consumable remelting in step S1 is 0.01-2.5 Pa, and the smelting temperature of the steel ingot is 1500-1600° C.; the pouring temperature of the steel ingot in step S1 is 1450-1530° C.

6. The method for producing anti-fatigue die steel according to claim 4, characterized in that: The multi-energy field treatment in step S1 includes ultrasonic treatment, microwave treatment and electromagnetic oscillation field treatment performed in sequence, the ultrasonic treatment has an ultrasonic frequency of 40-80KHZ, a power of 200-400W, and a time of 5-8min; the microwave treatment has a frequency of 2.0-2.5GHz, a power of 700-1300W, and a time of 5-10min; the electromagnetic oscillation field treatment has a frequency of 15-30HZ, at which time the medium and low duty cycle is 15-25%, and the time is 3-5min.

7. The method for producing anti-fatigue die steel according to claim 4, characterized in that: The temperature of the homogenization treatment in step S2 is 1250-1300° C., the holding time is 6-9 hours, and then air-cooled to room temperature.

8. The method for producing anti-fatigue die steel according to claim 4, characterized in that: The starting forging temperature of the forging in step S2 is 1100-1140°C, and the final forging temperature is 860-890°C; after forging, the steel is mist-cooled to 400-450°C, and then placed in a heating furnace with an internal temperature of 360-430°C, kept warm for 25-40 minutes, and then cooled to room temperature with the furnace.

9. The method for producing anti-fatigue die steel according to claim 4, characterized in that: The heat treatment in step S2 includes annealing and tempering.

10. The method for producing anti-fatigue die steel according to claim 9, characterized in that: The temperature of the annealing treatment is 820-880° C., and the holding time is 1-3 hours; the temperature of the tempering treatment is 180-210° C., and the holding time is 1-2 hours.

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