A mold steel convenient for heat treatment and preparation method thereof

Abstract

The invention discloses a die steel that is easy to heat treat. The raw materials for preparing the die steel are as follows: C: 0.3-0.8%, Cr: 2.0-3.2%, V: 0.5-1.2%, Mo: 0.4-1.5%, Nb: 0.3-1.6%, HfC: 0.3-0.8%, and the balance is Fe. The invention also discloses a preparation method of the die steel. Compared with the prior art, the invention has the following advantages: hafnium carbide is added to the composition of the raw materials, so that the dendrite structure of the casting steel is refined to varying degrees, and because the content of the Cr element in the invention is relatively high, the diffusion degree of the Cr element in the composition of the raw materials is increased during the preparation process, so that the Cr in the oxide layer is reduced. x O y The content is increased, thereby improving the antioxidant performance, slowing down the initiation and expansion of fatigue cracks, and ultimately enhancing the wear resistance of the obtained mold steel; the present invention adjusts the components prepared by the raw materials of the mold steel and combines the coating coating process, so that the mold steel only needs to use a general heat treatment process to have high wear resistance and high mechanical strength.

Description

Technical Field

[0001] The invention relates to the technical field of steel, and in particular to a die steel that is easy to heat treat and a preparation method thereof. Background Art

[0002] Stamping dies (cold stamping dies for short) are usually installed on a press to apply deformation force to the sheet metal placed inside at room temperature, so as to deform it and obtain special tools for product parts with certain shapes, sizes and performances. Cold stamping dies have developed from single blanking and single punching dies to blanking and punching compound dies. Due to the emergence of standard parts for cold stamping die frames, the design structure of dies has become more diverse, and the precision has also been improved. At the same time, in order to increase the service life of cold stamping dies and facilitate their use in machine tools such as forming grinding, electric pulse and wire cutting machines, the heat treatment process of using cemented carbide as the die material is relatively complicated, which will greatly increase the labor cost in factory production applications; and in use, even if these steels undergo complex heat treatment processes, the strength and hardness of the die steel obtained are low, which makes the wear resistance of the die poor, the finish is low, and the service life is also low, thereby affecting the service life of the die and further increasing the use cost of the enterprise. Summary of the invention

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a mold steel that is easy to heat treat, which not only has high wear resistance but also high mechanical strength. The heat treatment method used in preparing this mold steel is simple, and the stamping mold made therefrom has a long service life, which can reduce the company's use cost.

[0004] To solve the above problems, the present invention provides a mold steel that is easy to heat treat. The raw materials for preparing the mold steel are prepared in the following weight ratios: C: 0.3-0.8%, Cr: 2.0-3.2%, V: 0.5-1.2%, Mo: 0.4-1.5%, Nb: 0.3-1.6%, HfC: 0.3-0.8%, and the balance is Fe.

[0005] Preferably, the raw materials for preparing the mold steel are arranged in the following weight ratios: C: 0.5-0.7%, Cr: 2.2-2.8%, V: 0.7-1.0%, Mo: 0.6-1.1%, Nb: 0.5-1.3%, HfC: 0.5-0.6%, and the balance is Fe.

[0006] Hafnium carbide (HfC) is a gray solid with metallic luster. It has the highest melting point among known single compounds and is a good material for the lining of high-melting-point metal melting crucibles. It has excellent properties such as high melting point, high hardness, good high-temperature strength, good corrosion resistance and low thermal conductivity. It can be used as an additive for cemented carbide. After adding hafnium carbide to the raw material, the dendrite structure of the cast steel is refined to varying degrees. Since the content of Cr in the present invention is relatively high, the diffusion degree of Cr in the raw material preparation composition increases during the preparation process, so that the Cr in the oxide layer is x O y The content increases, thereby improving the oxidation resistance and slowing down the initiation and expansion of fatigue cracks; while the refinement of dendrites and the improvement of high-temperature oxidation resistance increase the yield strength of the mold steel and increase the threshold value of stress concentration required for fatigue crack initiation, thereby enhancing the wear resistance of the obtained mold steel.

[0007] Another object of the present invention is to provide a method for preparing mold steel that is easy to heat treat, the preparation method comprising the following steps:

[0008] S1. Melting: batching and putting the raw materials into a medium frequency furnace for melting. When the temperature of the molten steel is 1200-1500°C, the molten steel is deoxidized, and then inoculated to obtain a mold steel blank by casting.

[0009] S2. Heat treatment: the mold steel blank is subjected to annealing treatment, quenching treatment and then tempering treatment to obtain a mold steel semi-finished product;

[0010] S3, coating: Activate the semi-finished mold steel product, immerse it in a polytetrafluoroethylene assembly solution after one cleaning, take it out after coating and perform a second cleaning, and bake it for 60-80 minutes to obtain the finished mold steel product.

[0011] The present invention applies PTFE coating on the surface of mold steel. For molecular structure, the carbon chain of general polyolefin molecules is zigzag. For example, if hydrogen atoms are replaced with fluorine atoms, the fluorine atoms have large electronegativity, small atomic radius, short CF bond, bond energy up to 500kj / mol, symmetrical distribution, and low polarizability of fluorine atoms. The dielectric constant and loss factor of fluorocarbon compounds are very small, so they are highly inert chemically. In the perfluorocarbon chain, the sum of the van der Waals radius of two fluorine atoms is 0.27nm, which basically surrounds and fills the CCC bond. This almost void-free space barrier prevents any atom or group from entering and destroying the CC bond. Since the PTFE main chain has high rigidity and good crystallinity, and does not carry any functional group, its processability, solubility and compatibility are very poor. At the same time, PTFE (polytetrafluoroethylene) has a low friction coefficient and is a friction-reducing self-lubricating material with excellent wear resistance and thermal stability. It can penetrate into the porous material of the membrane and be coated on the surface, thereby improving the wear resistance of the material.

[0012] Preferably, in step S1, the deoxidation treatment comprises the following steps: adding 0.5-0.8% by weight of Mn and 1-2% by weight of Si to the molten steel for pre-deoxidation, and adding carbon powder for final deoxidation after thin slag is formed on the surface of the molten steel.

[0013] Preferably, in step S1, the inoculation treatment adopts the injection method, and the inoculant is 75SiFe. The applicant has obtained through multiple experiments that the die steel inoculated with 75SiFe has the largest amount of graphite precipitation, and the length of the graphite sheet increases, and chrysanthemum-shaped graphite appears locally. At the same time, since Si is an element that strongly promotes graphitization, after adding 75SiFe in the present invention, the white cast iron tendency of the molten iron is significantly reduced, and the amount of graphite precipitation increases and the size increases.

[0014] Preferably, in step S2, the annealing temperature is 700-800°C, the quenching temperature is 960-1050°C, the quenching medium is engine oil, the tempering temperature is 400-500°C, the tempering medium is air, and the tempering holding time is 2-2.5h.

[0015] Preferably, in step S3, the activation time is 20-30s, and the activation solution is a nitric acid solution of 6-8mol / L. The present invention performs an activation treatment on the mold steel semi-finished product before coating it. A layer of chromium oxide film is formed on the surface of the mold steel semi-finished product after the activation treatment, which can not only prevent harmful ions from causing harmful corrosion to the mold steel surface, but also the micropores of the chromium oxide film generated by it can introduce PTFE particles into the micropores in the subsequent polytetrafluoroethylene coating to fill them up. When the mold steel thus prepared is in use, when encountering friction and wear, the two friction surfaces are separated, thereby providing an interface with low shear resistance, thereby effectively reducing the friction coefficient and avoiding adhesion. From a certain perspective, the preparation method of the present invention generates a composite coating on the mold steel surface through activation and coating, and the micropores generated by the activation layer can be sealed by the PTFE particles in the PTFE coating, thereby further improving the friction resistance and corrosion resistance of the mold steel.

[0016] As preferably, in the step S3, the preparation method of the polytetrafluoroethylene assembly solution comprises the following steps: after the polytetrafluoroethylene ultrafine particles are activated by sodium naphthalene activation liquid, amino undecanoic acid molecules are grafted on the surface, the ultrafine particles are filtered out, and the ultrafine particles are repeatedly rinsed several times with acetone, and dried, and then the grafted PTFE particles are dispersed in n-hexane solution. The polytetrafluoroethylene ultrafine particles have excellent chemical stability and mechanical properties, but the surface wettability of the polytetrafluoroethylene particles is extremely poor, and it is difficult to combine with other materials. Therefore, if the polytetrafluoroethylene particles are directly used to prepare the coating on the die steel surface, it cannot be fixed on the metal surface in an orderly manner. Therefore, the present invention carries out surface modification treatment to the polytetrafluoroethylene particles, first adopts sodium naphthalene activation liquid to carry out activation treatment to the polytetrafluoroethylene particles, to introduce functional groups such as hydroxyl, carbonyl, carboxyl, and amino undecanoic acid carbon chains are grafted on the surface of the polytetrafluoroethylene ultrafine particles after activation by condensation reaction, so that in the coating coating, by the connection of amino undecanoic acid carbon chains, the polytetrafluoroethylene particles are orderly fixed on the metal surface.

[0017] Preferably, in step S3, the washing liquid for the first washing and the second washing is anhydrous ethanol, and the baking temperature is 100-120°C.

[0018] Compared with the prior art, the present invention has the following advantages: First, the present invention refines the dendrite structure of the cast steel to varying degrees by adding hafnium carbide to the composition, and because the content of Cr in the present invention is relatively high, the diffusion degree of Cr in the raw material composition is increased during the preparation process, so that the Cr in the oxide layer is x O yThe content is increased, thereby improving the antioxidant performance, slowing down the initiation and expansion of fatigue cracks, and ultimately enhancing the wear resistance of the obtained mold steel; secondly, the present invention combines the activation treatment of the mold steel semi-finished product with the coating of the polytetrafluoroethylene coating, and the micropores generated by the activation layer can be sealed by the PTFE particles in the PTFE coating, so that a dense layer is formed on the surface of the obtained mold steel; thirdly, the present invention activates the polytetrafluoroethylene particles, and in the coating coating, the polytetrafluoroethylene particles are orderly fixed on the metal surface through the connection of the aminoundecanoic acid carbon chain, thereby further improving the friction resistance and corrosion resistance of the mold steel; fourthly, the present invention adjusts the components of the mold steel and combines the coating coating process, so that the mold steel only needs to use a general heat treatment process to have high wear resistance and high mechanical strength. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0020] Example 1

[0021] In this embodiment, the raw materials for preparing the mold steel are as follows: C: 0.3%, Cr: 2.0%, V: 0.5%, Mo: 0.4%, Nb: 0.3%, HfC: 0.3%, and the balance is Fe. The preparation method is as follows:

[0022] S1, smelting: the ingredients are prepared according to the components of the mold steel, and the raw materials are put into the medium frequency furnace for smelting. When the temperature of the molten steel is 1200°C, the molten steel is deoxidized. The deoxidation treatment includes the following steps: adding 0.5% by weight of Mn and 1% by weight of Si to the molten steel for pre-deoxidation, adding carbon powder for final deoxidation after thin slag is formed on the surface of the molten steel, and then inoculating the molten steel by the flushing method after the deoxidation treatment, and the inoculant is 75SiFe, and finally casting to obtain the mold steel blank;

[0023] S2, heat treatment: the mold steel blank is subjected to annealing treatment and quenching treatment and then tempering treatment to obtain a mold steel semi-finished product. In the embodiment of the present invention, the annealing temperature is 700° C., the quenching temperature is 960° C., the quenching medium is engine oil, the tempering temperature is 400° C., the tempering medium is air, and the tempering holding time is 2 hours;

[0024] S3. Coating: After the polytetrafluoroethylene ultrafine particles are activated by sodium naphthalene activation solution, amino undecanoic acid molecules are grafted onto the surface, the ultrafine particles are filtered out, rinsed repeatedly with acetone for several times, and dried, and then the grafted PTFE particles are dispersed in n-hexane solution to obtain a polytetrafluoroethylene assembly solution, and then the mold steel semi-finished product is first activated with a 6 mol / L nitric acid solution for 20 seconds, and then washed once with anhydrous ethanol and immersed in the polytetrafluoroethylene assembly solution. After the coating is applied, it is taken out and washed twice with anhydrous ethanol, and finally baked at 100°C for 60 minutes to obtain the mold steel finished product.

[0025] Example 2

[0026] In this embodiment, the raw materials for preparing the mold steel are as follows: C: 0.5%, Cr: 2.2%, V: 0.7%, Mo: 0.6%, Nb: 0.5%, HfC: 0.5%, and the balance is Fe. The preparation method is as follows:

[0027] S1, smelting: the ingredients are prepared according to the components of the mold steel, and the raw materials are put into the medium frequency furnace for smelting. When the temperature of the molten steel is 1200-1500°C, the molten steel is deoxidized. The deoxidation treatment includes the following steps: adding 0.6% by weight of Mn and 1.2% by weight of Si to the molten steel for pre-deoxidation, adding carbon powder for final deoxidation after thin slag is formed on the surface of the molten steel, and then inoculating the molten steel by the flushing method after the deoxidation treatment, the inoculant is 75SiFe, and finally casting to obtain the mold steel blank;

[0028] S2, heat treatment: the mold steel blank is subjected to annealing treatment and quenching treatment and then tempering treatment to obtain a mold steel semi-finished product. In the embodiment of the present invention, the annealing temperature is 720° C., the quenching temperature is 980° C., the quenching medium is engine oil, the tempering temperature is 420° C., the tempering medium is air, and the tempering holding time is 2.1 h;

[0029] S3. Coating: After the polytetrafluoroethylene ultrafine particles are activated by sodium naphthalene activation solution, amino undecanoic acid molecules are grafted onto the surface, the ultrafine particles are filtered out, rinsed repeatedly with acetone for several times, and dried, and then the grafted PTFE particles are dispersed in n-hexane solution to obtain a polytetrafluoroethylene assembly solution, and then the mold steel semi-finished product is first activated with a 6.5 mol / L nitric acid solution for 22 seconds, and then rinsed once with anhydrous ethanol and immersed in the polytetrafluoroethylene assembly solution. After the coating is applied, it is taken out and rinsed twice with anhydrous ethanol, and finally baked at 105°C for 65 minutes to obtain the mold steel finished product.

[0030] Example 3

[0031] In this embodiment, the raw materials for preparing the mold steel are as follows: C: 0.6%, Cr: 2.5%, V: 0.8%, Mo: 0.8%, Nb: 0.9%, HfC: 0.55%, and the balance is Fe. The preparation method is as follows:

[0032] S1, smelting: the ingredients are prepared according to the components of the mold steel, and the raw materials are put into the medium frequency furnace for smelting. When the temperature of the molten steel is 1300°C, the molten steel is deoxidized. The deoxidation treatment includes the following steps: adding 0.65% by weight of Mn and 1.5% by weight of Si to the molten steel for pre-deoxidation, adding carbon powder for final deoxidation after thin slag is formed on the surface of the molten steel, and then inoculating the molten steel by the flushing method after the deoxidation treatment, and the inoculant is 75SiFe, and finally casting to obtain the mold steel blank;

[0033] S2, heat treatment: the mold steel blank is subjected to annealing treatment and quenching treatment and then tempering treatment to obtain a mold steel semi-finished product. In the embodiment of the present invention, the annealing temperature is 750° C., the quenching temperature is 1000° C., the quenching medium is engine oil, the tempering temperature is 450° C., the tempering medium is air, and the tempering holding time is 2.2 h;

[0034] S3. Coating: After the polytetrafluoroethylene ultrafine particles are activated by sodium naphthalene activation solution, amino undecanoic acid molecules are grafted onto the surface, the ultrafine particles are filtered out, rinsed repeatedly with acetone for several times, and dried, and then the grafted PTFE particles are dispersed in n-hexane solution to obtain a polytetrafluoroethylene assembly solution, and then the mold steel semi-finished product is first activated with 7mol / L nitric acid solution for 25s, washed once with anhydrous ethanol and immersed in the polytetrafluoroethylene assembly solution, taken out after coating and washed twice with anhydrous ethanol, and finally baked at 110°C for 70min to obtain the mold steel finished product.

[0035] Example 4

[0036] In this embodiment, the raw materials for preparing the mold steel are as follows: C: 0.7%, Cr: 2.8%, V: 1.0%, Mo: 1.1%, Nb: 1.3%, HfC: 0.6%, and the balance is Fe. The preparation method is as follows:

[0037] S1, smelting: the ingredients are prepared according to the components of the mold steel, and the raw materials are put into the medium frequency furnace for smelting. When the temperature of the molten steel is 1400°C, the molten steel is deoxidized. The deoxidation treatment includes the following steps: adding 0.7% by weight of Mn and 1.8% by weight of Si to the molten steel for pre-deoxidation, adding carbon powder for final deoxidation after thin slag is formed on the surface of the molten steel, and then inoculating the molten steel by the flushing method after the deoxidation treatment, and the inoculant is 75SiFe, and finally casting to obtain the mold steel blank;

[0038] S2, heat treatment: the mold steel blank is subjected to annealing treatment and quenching treatment and then tempering treatment to obtain a mold steel semi-finished product. In the embodiment of the present invention, the annealing temperature is 780° C., the quenching temperature is 1020° C., the quenching medium is engine oil, the tempering temperature is 480° C., the tempering medium is air, and the tempering holding time is 2.4 h;

[0039] S3. Coating: After the polytetrafluoroethylene ultrafine particles are activated by sodium naphthalene activation solution, amino undecanoic acid molecules are grafted onto the surface, the ultrafine particles are filtered out, rinsed repeatedly with acetone for several times, and dried, and then the grafted PTFE particles are dispersed in n-hexane solution to obtain a polytetrafluoroethylene assembly solution, and then the mold steel semi-finished product is first activated with 7.5 mol / L nitric acid solution for 28 seconds, and then washed once with anhydrous ethanol and immersed in the polytetrafluoroethylene assembly solution. After the coating is applied, it is taken out and washed twice with anhydrous ethanol, and finally baked at 115°C for 75 minutes to obtain the mold steel finished product.

[0040] Example 5

[0041] In this embodiment, the raw materials for preparing the mold steel are as follows: C: 0.8%, Cr: 3.2%, V: 1.2%, Mo: 1.5%, Nb: 1.6%, HfC: 0.8%, and the balance is Fe. The preparation method is as follows:

[0042] S1, smelting: the ingredients are prepared according to the components of the mold steel, and the raw materials are put into the medium frequency furnace for smelting. When the temperature of the molten steel is 1500°C, the molten steel is deoxidized. The deoxidation treatment includes the following steps: adding 0.8% by weight of Mn and 2% by weight of Si to the molten steel for pre-deoxidation, adding carbon powder for final deoxidation after thin slag is formed on the surface of the molten steel, and then inoculating the molten steel by the flushing method after the deoxidation treatment, the inoculant is 75SiFe, and finally casting to obtain the mold steel blank;

[0043] S2, heat treatment: the mold steel blank is subjected to annealing treatment and quenching treatment and then tempering treatment to obtain a mold steel semi-finished product. In the embodiment of the present invention, the annealing temperature is 800° C., the quenching temperature is 1050° C., the quenching medium is engine oil, the tempering temperature is 500° C., the tempering medium is air, and the tempering holding time is 2.5 h;

[0044] S3. Coating: After the polytetrafluoroethylene ultrafine particles are activated by sodium naphthalene activation solution, amino undecanoic acid molecules are grafted onto the surface, the ultrafine particles are filtered out, rinsed repeatedly with acetone for several times, and dried, and then the grafted PTFE particles are dispersed in n-hexane solution to obtain a polytetrafluoroethylene assembly solution, and then the mold steel semi-finished product is first activated with 8 mol / L nitric acid solution for 30 seconds, and then washed once with anhydrous ethanol and immersed in the polytetrafluoroethylene assembly solution. After the coating is applied, it is taken out and washed twice with anhydrous ethanol, and finally baked at 120°C for 80 minutes to obtain the mold steel finished product.

[0045] Comparative Example 1

[0046] The only difference from Example 3 is that the raw material composition of the mold steel in this comparative example does not contain HfC, and the rest is the same as Example 3 and will not be repeated here.

[0047] Comparative Example 2

[0048] The only difference from Example 3 is that, when preparing the comparative example mold steel, in step S3, the mold steel semi-finished product is not activated, and the rest is the same as Example 3 and will not be described again.

[0049] Comparative Example 3

[0050] The only difference from Example 3 is that, when preparing the comparative mold steel, in step S3, the ultrafine polytetrafluoroethylene particles are not activated. The rest is the same as Example 3 and will not be described again.

[0051] Comparative Example 4

[0052] The only difference from Example 3 is that the surface of the comparative mold is not coated, that is, the process of step S3 is not performed. The rest is the same as Example 3 and will not be repeated here.

[0053] The die steels obtained in Examples 1-5 and Comparative Examples 1-4 were subjected to performance tests, and the test results are shown in Table 1:

[0054] Table 1: Test results of die steel properties obtained in Examples 1-5 and Comparative Examples 1-4

[0055] Hardness (HB) Tensile strength (MPa) Impact toughness ak(J / cm2) Example 1 266 82 52 Example 2 274 84 57 Example 3 282 87 58 Example 4 278 86 56 Example 5 271 82 51 Comparative Example 1 248 69 47 Comparative Example 2 254 57 45 Comparative Example 3 269 78 49 Comparative Example 4 235 49 38

[0056] Among them, the hardness test method is based on GB / T230.1.

[0057] It can be seen from the above results that the dendrite structure of the cast steel is refined to varying degrees by adding hafnium carbide to the composition of the present invention, and because the content of Cr element in the present invention is relatively high, the diffusion degree of Cr element in the raw material composition is increased during the preparation process, so that the Cr in the oxide layer is xO y The content is increased, thereby improving the antioxidant performance, slowing down the initiation and expansion of fatigue cracks, and ultimately enhancing the wear resistance of the obtained mold steel; the present invention combines the activation treatment of the mold steel semi-finished product with the coating of the polytetrafluoroethylene coating, and the micropores generated by the activation layer can be sealed by the PTFE particles in the PTFE coating, so that a dense layer is formed on the surface of the obtained mold steel; the present invention performs an activation treatment on the polytetrafluoroethylene particles, and in the coating coating, the polytetrafluoroethylene particles are orderly fixed on the metal surface through the connection of the aminoundecanoic acid carbon chain, thereby further improving the friction resistance and corrosion resistance of the mold steel; at the same time, the present invention adjusts the components of the mold steel and combines the coating coating process, so that the mold steel only needs to use a general heat treatment process to have high wear resistance and high mechanical strength.

[0058] Although the disclosure is disclosed as above, the protection scope of the disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A die steel that is easy to heat treat, characterized in that: The raw materials for preparing the mold steel are as follows: C: 0.3-0.8%, Cr: 2.0-3.2%, V: 0.5-1.2%, Mo: 0.4-1.5%, Nb: 0.3-1.6%, HfC: 0.3-0.8%, and the balance is Fe; the processing method of the mold steel comprises the following steps: S1. Melting: batching and putting the raw materials into a medium frequency furnace for melting. When the temperature of the molten steel is 1200-1500°C, the molten steel is deoxidized, and then inoculated to obtain a mold steel blank by casting. S2. Heat treatment: the mold steel blank is subjected to annealing treatment, quenching treatment, and then tempering treatment to obtain a mold steel semi-finished product; S3, coating: Activate the semi-finished mold steel product, immerse it in a polytetrafluoroethylene assembly solution after cleaning once, take it out after coating, clean it twice, and bake it for 60-80 minutes to obtain the finished mold steel product; In step S3, the activation time is 20-30s, and the activation solution is 6-8mol / L nitric acid solution; In step S3, the preparation method of the polytetrafluoroethylene assembly solution includes the following steps: activating the polytetrafluoroethylene ultrafine particles with sodium naphthalene activation solution, grafting aminoundecanoic acid molecules on the surface, filtering out the ultrafine particles, repeatedly washing with acetone for several times, and drying, and then dispersing the grafted PTFE particles in a n-hexane solution.

2. The die steel that is easy to heat treat according to claim 1, characterized in that: The raw materials for preparing the mold steel are as follows according to their weight ratio: C: 0.5-0.7%, Cr: 2.2-2.8%, V: 0.7-1.0%, Mo: 0.6-1.1%, Nb: 0.5-1.3%, HfC: 0.5-0.6%, and the balance is Fe.

3. The die steel that is easy to heat treat according to claim 1, characterized in that: In step S1, the deoxidation treatment includes the following steps: adding 0.5-0.8% by weight of Mn and 1-2% by weight of Si to the molten steel for pre-deoxidation, and adding carbon powder for final deoxidation after thin slag is formed on the surface of the molten steel.

4. The die steel that is easy to heat treat according to claim 1, characterized in that: In the step S1, the inoculation treatment adopts the injection method, and the inoculant is 75SiFe.

5. The die steel that is easy to heat treat according to claim 1, characterized in that: In step S2, the temperature of annealing treatment is 700-800°C, the temperature of quenching treatment is 960-1050°C, the medium of quenching treatment is engine oil, the temperature of tempering treatment is 400-500°C, the tempering medium is air, and the tempering holding time is 2-2.5h.

6. The die steel that is easy to heat treat according to claim 1, characterized in that: In step S3, the washing liquid for the first washing and the second washing is anhydrous ethanol.

7. The die steel that is easy to heat treat according to claim 1, characterized in that: In step S3, the baking temperature is 100-120°C.