CN116145035B - Additive manufacturing hot work die steel based on in-situ alloying technology and preparation method thereof - Google Patents

Abstract

The invention provides an additive manufacturing hot work die steel based on an in-situ alloying technology and a preparation method thereof. The die steel comprises powder A and powder B; the powder A contains 0.35 to 0.39 percent of carbon; nitrogen 0.01-0.02%; 0.9-1.2% of silicon; manganese 0.1-0.4%; chromium 5.2-5.8%; 0.9 to 1.2 percent of vanadium; 1.2 to 1.3 percent of molybdenum; sulfur 0.001-0.003%; 0.005-0.01% of phosphorus; oxygen 0.01-0.035%, and iron in balance; the powder B contains 0.001-0.008% of carbon; 16-18% of chromium; 2-2.5% of molybdenum; manganese 0.2-0.7%; 0.3-0.5% of silicon; 9.5-11% of nickel; sulfur 0.001-0.003%; 0.005-0.01% of phosphorus; oxygen 0.01-0.035%, and iron in balance. The die steel can realize good matching of strength, plasticity and toughness.

Description

An additive manufacturing hot working die steel based on in-situ alloying technology and its preparation method

Technical Field

The invention relates to an additively manufactured hot working die steel based on an in-situ alloying technology and a preparation method thereof, belonging to the technical field of alloy materials.

Background Art

Hot working die steel is widely used in non-ferrous metal die-casting, extrusion and forging. Additive manufacturing technology has great advantages in complex shape design, especially in the design of conformal cooling water channels for hot working dies. The implementation of conformal cooling design can make the die dissipate heat faster and more evenly, while reducing the service life of the die. The dimensional accuracy and quality of hot-processed products can also be improved.

Among traditional hot working die steels, H13 alloy has excellent comprehensive mechanical properties, but cracking will occur during the additive manufacturing process and the printing performance is poor, which greatly limits the application of traditional hot working die steel materials in the field of additive manufacturing.

At present, 18Ni300 alloy is mainly used to replace traditional hot working die steel in hot working die steel for additive manufacturing. This alloy can effectively avoid cracking during the printing process, but the alloy contains a large amount of Co and Ni elements, the cost is relatively high, and the performance at high temperatures is poor, which cannot meet the use of die steel under high temperature operations. Especially in the field of non-ferrous metal die-casting, there is no special mold material suitable for additive manufacturing and with the performance of traditional hot working die steel. Therefore, the development of low-cost, high-performance hot working die steel materials suitable for additive manufacturing has great application value.

Summary of the invention

In order to solve the above technical problems, the purpose of the present invention is to provide a hot working die steel for additive manufacturing based on in-situ alloying technology and a preparation method thereof, and to obtain hot working die steel suitable for additive manufacturing by adopting low-cost preparation technology.

To achieve the above object, the present invention provides an additively manufactured hot working die steel based on in-situ alloying technology, which includes A alloy powder and B alloy powder;

Wherein, based on the weight of the A alloy powder as 100%, the element composition of the A alloy powder includes: carbon: 0.35%-0.39%; nitrogen: 0.01%-0.02%; silicon: 0.9%-1.2%; manganese: 0.1%-0.4%; chromium: 5.2%-5.8%; vanadium: 0.9%-1.2%; molybdenum: 1.2%-1.3%; sulfur: 0.001%-0.003%; phosphorus: 0.005%-0.01%; oxygen: 0.01%-0.035%, and the rest is iron;

Taking the weight of the B alloy powder as 100%, the element composition of the B alloy powder includes: carbon: 0.001%-0.008%; chromium: 16%-18%; molybdenum: 2%-2.5%; manganese: 0.2%-0.7%; silicon: 0.3%-0.5%; nickel: 9.5%-11%; sulfur: 0.001%-0.003%; phosphorus: 0.005%-0.01%; oxygen: 0.01%-0.035%, and the rest is iron.

According to a specific embodiment of the present invention, preferably, in the above-mentioned additive manufacturing hot working die steel, the weight ratio of the A alloy powder to the B alloy powder is 5.6:1-6.3:1.

According to a specific embodiment of the present invention, preferably, in the above-mentioned additive manufacturing hot working die steel, the element composition of the A alloy powder includes: carbon: 0.35%; nitrogen: 0.01%; silicon: 0.9%; manganese: 0.4%; chromium: 5.2%; vanadium: 0.9%; molybdenum: 1.2%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron;

The element composition of the B alloy powder includes: carbon: 0.008%; chromium: 16%; molybdenum: 2%; manganese: 0.2%; silicon: 0.3%; nickel: 9.5%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron;

The mass ratio of the A alloy powder to the B alloy powder is 5.6:1.

According to a specific embodiment of the present invention, preferably, in the above-mentioned additive manufacturing hot working die steel, the element composition of the A alloy powder includes: carbon: 0.39%; nitrogen: 0.02%; silicon: 1.2%; manganese: 0.1%; chromium: 5.8%; vanadium: 1.2%; molybdenum: 1.3%; sulfur: 0.003%; phosphorus: 0.01; oxygen: 0.035%, and the rest is iron;

The element composition of the B alloy powder includes: carbon: 0.001%; chromium: 18%; molybdenum: 2.5%; manganese: 0.7%; silicon: 0.5%; nickel: 11%; sulfur: 0.003%; phosphorus: 0.01%; oxygen: 0.035%, and the rest is iron;

The mass ratio of the A alloy powder to the B alloy powder is 6.3:1.

According to a specific embodiment of the present invention, preferably, in the above-mentioned additive manufacturing hot working die steel, the element composition of the A alloy powder includes: carbon: 0.37%; nitrogen: 0.01%; silicon: 0.9%; manganese: 0.3%; chromium: 5.2%; vanadium: 1%; molybdenum: 1.2%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron;

The element composition of the B alloy powder includes: carbon: 0.001%; chromium: 16%; molybdenum: 2%; manganese: 0.2%; silicon: 0.3%; nickel: 10%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron;

The mass ratio of the A alloy powder to the B alloy powder is 6:1.

According to a specific embodiment of the present invention, preferably, the above-mentioned additive manufacturing hot working die steel does not contain precious metal elements such as Co.

The additive manufacturing hot working die steel of the present invention comprises two alloy powders A and B of different compositions, wherein the alloy powder A is a medium carbon alloy and the alloy powder B is an ultra-low carbon alloy. During preparation, the powder of the alloy A and the powder of the alloy B can be uniformly mixed by mechanical mixing to serve as the alloy powder before additive manufacturing.

The present invention also provides a method for preparing the above-mentioned additively manufactured hot working die steel based on the in-situ alloying technology, which comprises the following steps:

A alloy powder and B alloy powder are mixed, and then laser powder bed melting is performed to obtain an alloy (alloys of a desired shape and size can be obtained as required), and the alloy is placed in liquid nitrogen for heat preservation;

The alloy that has been heat-insulated with liquid nitrogen is kept at 570°C-590°C and then air-cooled to obtain the additive manufacturing hot working die steel; or, the alloy that has been heat-insulated with liquid nitrogen is kept at 570°C-590°C and then air-cooled to room temperature and then kept at 570°C-590°C and then air-cooled to obtain the additive manufacturing hot working die steel; or, the alloy that has been heat-insulated with liquid nitrogen is kept at 220°C-280°C and then air-cooled to obtain the additive manufacturing hot working die steel.

According to a specific embodiment of the present invention, preferably, in the above preparation method, the process parameters of the laser powder bed melting are: laser power of 100W-150W, scanning speed of 600mm/s-800mm/s, layer thickness of 20μm-30μm, scanning spacing of 75-90μm. The substrate material used can be 316L.

According to a specific embodiment of the present invention, preferably, in the above preparation method, the alloy is placed in liquid nitrogen for 30 minutes.

According to a specific embodiment of the present invention, preferably, in the above preparation method, the alloy is kept at 570°C-590°C for 2 hours, and the alloy is kept at 220°C-280°C for 3 minutes, that is, after the alloy is kept in liquid nitrogen, the following treatments may be taken:

The alloy that has been heat-insulated with liquid nitrogen is kept at 570°C-590°C for 2 hours and then air-cooled to obtain the additive manufacturing hot working die steel; or, the alloy that has been heat-insulated with liquid nitrogen is kept at 570°C-590°C for 2 hours and then air-cooled to room temperature and then kept at 570°C-590°C for 2 hours to obtain the additive manufacturing hot working die steel; or, the alloy that has been heat-insulated with liquid nitrogen is kept at 220°C-280°C for 3 minutes and then air-cooled to obtain the additive manufacturing hot working die steel.

According to a specific embodiment of the present invention, preferably, in the above preparation method, the alloy that has been heat-insulated with liquid nitrogen is kept at 580° C. for 2 hours and then air-cooled to room temperature, and then continued to be kept at 580° C. for 2 hours and then air-cooled.

The preparation method of hot working die steel for additive manufacturing based on in-situ alloying technology provided by the present invention mechanically mixes the medium carbon alloy and the ultra-low carbon alloy in an appropriate proportion, and then adopts additive manufacturing to obtain a crack-free hot working die steel material. The composition range and printing parameters are relatively wide, and the heat treatment process parameters are also relatively wide. The obtained hot working die steel can achieve a good match of strength, plasticity and toughness, and can be suitable for the application of high-strength steel under different service conditions. The mechanical properties of the alloy obtained by this method can reach the properties of traditional hot working die steel, and no precious metal elements such as Co are added, and the crack-free die steel material can be printed without preheating the substrate, which is low in cost and suitable for industrial production.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a metallographic photograph of the hot working die steel of Example 1 in the printed state.

DETAILED DESCRIPTION

In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

Example 1

This embodiment provides a hot working die steel, which comprises A alloy powder and B alloy powder, wherein:

Taking the weight of alloy A powder as 100%, the composition of alloy A powder is as follows: carbon: 0.35%; nitrogen: 0.01%; silicon: 0.9%; manganese: 0.4%; chromium: 5.2%; vanadium: 0.9%; molybdenum: 1.2%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron.

Taking the weight of the B alloy powder as 100%, the composition of the B alloy powder is: carbon: 0.008%; chromium: 16%; molybdenum: 2%; manganese: 0.2%; silicon: 0.3%; nickel: 9.5%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron.

The preparation process of the hot working die steel is as follows:

The powder of alloy A and the powder of alloy B were mechanically mixed at a weight ratio of 5.6:1, and the mold steel material was obtained by laser powder bed melting, wherein the process of laser powder bed melting was as follows: laser power was 130 W, scanning speed was 800 mm/s, layer thickness was 20 μm, scanning spacing was 80 μm, and substrate material was 316L;

Subsequently, the mold steel parts obtained by additive manufacturing were kept in liquid nitrogen for 30 minutes and then taken out. Then, they were kept at 580°C for 2 hours and then air-cooled to room temperature. After that, they were kept at 580°C for another 2 hours and then air-cooled to room temperature to obtain the final hot working mold steel.

The metallographic photograph of the mold steel cross section is shown in Figure 1. It can be seen from Figure 1 that there are no obvious printing holes and cracks in the cross section of the mold steel, the room temperature impact energy is 20J, and other mechanical properties are shown in Table 1.

Example 2

This embodiment provides a hot working die steel, which comprises A alloy powder and B alloy powder, wherein:

Taking the weight of alloy A powder as 100%, the composition of alloy A powder is as follows: carbon: 0.39%; nitrogen: 0.02%; silicon: 1.2%; manganese: 0.1%; chromium: 5.8%; vanadium: 1.2%; molybdenum: 1.3%; sulfur: 0.003%; phosphorus: 0.01; oxygen: 0.035%, and the rest is iron.

Taking the weight of the B alloy powder as 100%, the composition of the B alloy powder is: carbon: 0.001%; chromium: 18%; molybdenum: 2.5%; manganese: 0.7%; silicon: 0.5%; nickel: 11%; sulfur: 0.003%; phosphorus: 0.01%; oxygen: 0.035%, and the rest is iron.

The preparation process of the hot working die steel is as follows:

The powder of alloy A and the powder of alloy B were mechanically mixed at a weight ratio of 6.3:1 and then melted by laser powder bed to obtain the mold steel material, wherein the process of laser powder bed melting was as follows: laser power was 150 W, scanning speed was 800 mm/s, layer thickness was 20 μm, scanning interval was 80 μm, and substrate material was 316L;

The mold obtained by additive manufacturing was then taken out after being kept in liquid nitrogen for 30 minutes, and then air-cooled to room temperature after being kept at 580°C for 2 hours to obtain the final hot working die steel with an impact energy of 12 J at room temperature. Other mechanical properties are shown in Table 1.

Example 3

This embodiment provides a hot working die steel, which comprises A alloy powder and B alloy powder, wherein:

Taking the weight of alloy A powder as 100%, the composition of alloy A powder is as follows: carbon: 0.37%; nitrogen: 0.01%; silicon: 0.9%; manganese: 0.3%; chromium: 5.2%; vanadium: 1%; molybdenum: 1.2%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron.

Taking the weight of the B alloy powder as 100%, the composition of the B alloy powder is: carbon: 0.001%; chromium: 16%; molybdenum: 2%; manganese: 0.2%; silicon: 0.3%; nickel: 10%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron.

The preparation process of the hot working die steel is as follows:

The powder of alloy A and the powder of alloy B were mechanically mixed in a weight ratio of 6:1 and then melted by laser powder bed to obtain the mold steel material. The process of laser powder bed melting was as follows: laser power 130W, scanning speed 800mm/s, layer thickness 20μm, scanning interval 80μm, substrate material 316L;

Subsequently, the mold steel parts obtained by additive manufacturing were kept in liquid nitrogen for 30 minutes and then taken out. Then, they were kept at 280°C for 3 minutes and then air-cooled to room temperature to obtain the final hot working mold steel. The mechanical properties are shown in Table 1.

Example 4

This embodiment provides a hot working die steel, which comprises A alloy powder and B alloy powder, wherein:

Taking the weight of alloy A powder as 100%, the composition of alloy A powder is: carbon: 0.37%; nitrogen: 0.01%; silicon: 0.95%; manganese: 0.1%; chromium: 5.2%; vanadium: 0.98%; molybdenum: 1.2%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron.

Taking the weight of the B alloy powder as 100%, the composition of the B alloy powder is: carbon: 0.001%; chromium: 17%; molybdenum: 2%; manganese: 0.7%; silicon: 0.4%; nickel: 10.5%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.03%, and the rest is iron.

The preparation process of the hot working die steel is as follows:

The powder of alloy A and the powder of alloy B were mechanically mixed in a weight ratio of 6:1 and then melted by laser powder bed to obtain the mold steel material. The process of laser powder bed melting was as follows: laser power 130W, scanning speed 800mm/s, layer thickness 20μm, scanning interval 80μm, substrate material 316L;

Subsequently, the mold steel parts obtained by additive manufacturing were kept in liquid nitrogen for 30 minutes and then taken out. Then, they were kept at 220°C for 3 minutes and then air-cooled to room temperature to obtain the final hot working mold steel. The mechanical properties are shown in Table 1.

Table 1 Mechanical properties of the final alloys obtained in Examples 1-4

It can be seen from the mechanical property test results shown in Table 1 that the hot working die steel provided by the present invention can achieve a good match of strength, plasticity and toughness, and can be suitable for the application of high-strength steel in different service conditions.

Claims (8)

1. An additively manufactured hot working die steel based on in-situ alloying technology, comprising alloy A powder and alloy B powder; the weight ratio of alloy A powder to alloy B powder is 5.6:1-6.3:1; Wherein, based on the weight of the A alloy powder as 100%, the element composition of the A alloy powder includes: carbon: 0.35%-0.39%; nitrogen: 0.01%-0.02%; silicon: 0.9%-1.2%; manganese: 0.1%-0.4%; chromium: 5.2%-5.8%; vanadium: 0.9%-1.2%; molybdenum: 1.2%-1.3%; sulfur: 0.001%-0.003%; phosphorus: 0.005%-0.01%; oxygen: 0.01%-0.035%, and the rest is iron; Taking the weight of the B alloy powder as 100%, the element composition of the B alloy powder includes: carbon: 0.001%-0.008%; chromium: 16%-18%; molybdenum: 2%-2.5%; manganese: 0.2%-0.7%; silicon: 0.3%-0.5%; nickel: 9.5%-11%; sulfur: 0.001%-0.003%; phosphorus: 0.005%-0.01%; oxygen: 0.01%-0.035%, and the rest is iron. 2. The additive manufacturing hot working die steel according to claim 1, wherein the element composition of the A alloy powder comprises: carbon: 0.35%; nitrogen: 0.01%; silicon: 0.9%; manganese: 0.4%; chromium: 5.2%; vanadium: 0.9%; molybdenum: 1.2%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron; The element composition of the B alloy powder includes: carbon: 0.008%; chromium: 16%; molybdenum: 2%; manganese: 0.2%; silicon: 0.3%; nickel: 9.5%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron; The mass ratio of the A alloy powder to the B alloy powder is 5.6:1. 3. The additive manufacturing hot working die steel according to claim 1, wherein the element composition of the A alloy powder comprises: carbon: 0.39%; nitrogen: 0.02%; silicon: 1.2%; manganese: 0.1%; chromium: 5.8%; vanadium: 1.2%; molybdenum: 1.3%; sulfur: 0.003%; phosphorus: 0.01; oxygen: 0.035%, and the rest is iron; The element composition of the B alloy powder includes: carbon: 0.001%; chromium: 18%; molybdenum: 2.5%; manganese: 0.7%; silicon: 0.5%; nickel: 11%; sulfur: 0.003%; phosphorus: 0.01%; oxygen: 0.035%, and the rest is iron; The mass ratio of the A alloy powder to the B alloy powder is 6.3:1. 4. The additive manufacturing hot working die steel according to claim 1, wherein the element composition of the A alloy powder comprises: carbon: 0.37%; nitrogen: 0.01%; silicon: 0.9%; manganese: 0.3%; chromium: 5.2%; vanadium: 1%; molybdenum: 1.2%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron; The element composition of the B alloy powder includes: carbon: 0.001%; chromium: 16%; molybdenum: 2%; manganese: 0.2%; silicon: 0.3%; nickel: 10%; sulfur: 0.001%; phosphorus: 0.005%; oxygen: 0.01%, and the rest is iron; The mass ratio of the A alloy powder to the B alloy powder is 6:1. 5. The method for preparing hot working die steel by additive manufacturing based on in-situ alloying technology according to any one of claims 1 to 4, comprising the following steps: A alloy powder and B alloy powder are mixed, and then laser powder bed melting is performed to obtain an alloy, and the alloy is placed in liquid nitrogen for heat preservation; wherein the process parameters of the laser powder bed melting are: laser power of 100W-150W, scanning speed of 600mm/s-800mm/s, layer thickness of 20μm-30μm, and scanning spacing of 75μm-90μm; The alloy that has been heat-insulated with liquid nitrogen is kept at 570°C-590°C and then air-cooled to obtain the additive manufacturing hot working die steel; or, the alloy that has been heat-insulated with liquid nitrogen is kept at 570°C-590°C and then air-cooled to room temperature and then kept at 570°C-590°C and then air-cooled to obtain the additive manufacturing hot working die steel; or, the alloy that has been heat-insulated with liquid nitrogen is kept at 220°C-280°C and then air-cooled to obtain the additive manufacturing hot working die steel. 6. The preparation method according to claim 5, wherein the alloy is placed in liquid nitrogen for 30 minutes. 7. The preparation method according to claim 5, wherein the alloy is kept at 570°C-590°C for 2 hours, and the alloy is kept at 220°C-280°C for 3 minutes. 8. The preparation method according to claim 5, wherein the alloy that has been heat-insulated with liquid nitrogen is heat-insulated at 580°C for 2 hours and then air-cooled to room temperature, and then heat-insulated at 580°C for another 2 hours and then air-cooled.