CN118703834A - A Pr-doped reinforced pure titanium material and preparation method thereof - Google Patents

Abstract

The present invention relates to a Pr-doped reinforced pure titanium material and a preparation method thereof. The Pr-doped reinforced pure titanium material contains 0.01wt% to 1.5wt% of Pr, and the rest is Ti and inevitable impurities. The present invention improves the mechanical properties of the titanium material by doping a small amount of Pr element. The principle of the present invention is that the Pr element can be evenly distributed in the titanium material to strengthen the matrix, and Pr does not segregate and does not generate compounds that are easy to cause cracking, thereby achieving the strengthening of the titanium material. The present invention has low process cost, short process, good quality effect, and does not require large-scale equipment modification.

Description

A Pr-doped reinforced pure titanium material and preparation method thereof

Technical Field

The invention relates to the field of titanium metal, and in particular to a Pr-doped reinforced pure titanium material and a preparation method thereof.

Background Art

Titanium and titanium alloys have excellent physical and chemical properties and are important lightweight materials in the industrial field. They are widely used in aerospace, biomedicine, shipbuilding, automobile, petrochemical and other fields. Pure titanium has good ductility and high corrosion resistance, but its mechanical properties are poor, and its tensile strength is only ~300-400MPa. In order to improve the mechanical properties, it is generally necessary to strengthen it by adding a large amount of alloying elements, such as V, Nb, Mo and other elements. These elements are expensive and will greatly increase the processing cost and reduce the welding performance of titanium materials; in addition, the addition of a large amount of alloying elements will also cause the plasticity and toughness of titanium materials to drop significantly, and a large amount of alloying elements will also produce obvious segregation, which is not conducive to the overall performance control of titanium materials.

In addition to adding a large amount of alloying elements, strengthening can also be achieved by refining the grains. Grains can be greatly refined by severe plastic deformation. Typical methods include equal-diameter bending channel deformation, high-pressure torsion, multi-axis forging, etc. For example, publication number CN 103572186 "Method for preparing ultrafine-grained titanium-based composite materials using equal-diameter bending channel deformation" discloses a method for preparing high-strength titanium materials by severe plastic deformation; ultrafine-grained powders can also be strengthened by powder metallurgy. For example, CN 103938005 "Method for preparing ultrafine-grained titanium and titanium alloys by air flow grinding of hydrogenated titanium powder" discloses a method for improving the performance of titanium materials by sintering fine-grained powders. However, the use of this method has high equipment requirements, is difficult to process, and is not suitable for large-scale titanium production.

Summary of the invention

The present invention provides a Pr-doped reinforced pure titanium material and a preparation method thereof. The mechanical properties of the titanium material are increased by a trace amount of Pr doping. Pr can absorb oxygen elements in the titanium matrix and reduce the oxygen content in the matrix, thereby improving the plasticity and toughness of the titanium material; the dispersed Pr-rich particles can play a role in second phase strengthening. The Pr element can be used as a nucleation site to greatly refine the matrix grains. Doping 0.01%-1.5% of Pr can reduce the grain size by 10%-65%, playing a role in fine grain strengthening. In addition, during the processing, during the grain deformation of the Pr-containing titanium material, the dispersed Pr can pin the grain boundary and hinder the migration of the grain boundary during the deformation process, thereby achieving grain refinement. During forging and rolling, the grain crushing effect of the Pr-containing titanium material will be more obvious. That is, under a smaller processing amount, finer grains can be obtained, thereby ensuring a higher yield rate.

To achieve the above object, the present invention adopts the following technical solutions:

The invention discloses a Pr-doped reinforced pure titanium material, wherein the Pr-doped reinforced pure titanium material contains 0.01wt% to 1.5wt% of Pr, and the rest is Ti and inevitable impurities.

The tensile strength of the Pr-doped reinforced pure titanium material is 530 MPa to 660 MPa, the yield strength is 360 MPa to 550 MPa, and the elongation is 12% to 45%.

A method for preparing a Pr-doped reinforced pure titanium material, the method comprising the following steps:

1) Pure titanium particles and pure Pr particles are mixed and smelted in a vacuum or inert gas atmosphere to ensure that the oxygen content of the air is less than 500ppm during smelting.

2) The ingot is subjected to upsetting and drawing forging, the ingot is peeled, the riser and bottom are removed, and the ingot is ground forging. The cumulative height deformation of the upsetting and drawing forging is ≥120%, and the single deformation is 40% to 50%; the final forging temperature is ≥650°C.

3) After the forged slab is ground, it is rolled, and the total deformation of the rolling thickness is ≥60%.

4) The rolled slab is heat treated to eliminate the deformed structure: the heat treatment temperature is 700-850°C, the heat treatment time is 0.5-2h, and the cooling method is air cooling.

The purity of the pure titanium particles is ≥99.5%, and the purity of the pure Pr particles is ≥99.5%.

Before smelting, 1 wt% to 3 wt% of Pr element is additionally added to compensate for part of the Pr element volatilized due to smelting.

In the step 1), consumable melting or electron beam melting is selected, and when an inert gas is used as the protective gas for melting, helium or argon is selected.

In order to ensure uniform smelting composition and no obvious metallurgical defects in the ingot, the ingot is repeatedly smelted at least twice.

Before mixing, the titanium and Pr particles should be crushed into appropriate sizes, fully mixed and then melted. Plates with larger deformation will obtain finer and more uniform grains, and the mechanical properties will be improved accordingly; but it should be noted that plates with larger rolling deformation require larger forging deformation in the early stage to ensure rolling quality, which will increase processing costs and reduce the yield rate.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention improves the mechanical properties of titanium materials by doping a small amount of Pr elements. The principle of the present invention is that the Pr element can be evenly distributed in the titanium material to strengthen the matrix, and Pr does not segregate and does not generate compounds that are easy to cause cracking, thereby achieving the strengthening of the titanium material. The process cost of the present invention is low, the process is short, the quality effect is good, and there is no need to modify the equipment on a large scale. Different strengthening effects can be achieved by different addition amounts: when the addition amount is 0.01% to 1%, the strength of the titanium material is improved, and the tensile strength is increased from the original pure titanium plate to ≥530MPa, and the plasticity is maintained at the same level or slightly higher than the pure titanium plate; when the addition amount is greater than 1%, the strength of the titanium material is greatly improved, and the tensile strength is greater than 620MPa, but the strengthening is at the expense of a large amount of titanium material toughness. The present invention can achieve rapid and flexible preparation of titanium materials with different strengths and toughness combinations through different doping amounts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the microstructure of titanium material according to Example 3 of the present invention.

FIG. 2 is a diagram of the organizational structure of Comparative Example 1 of the present invention.

FIG. 3 is a diagram of the organizational structure of Comparative Example 2 of the present invention.

DETAILED DESCRIPTION

In order to more intuitively embody the present invention, the present invention is further described in conjunction with embodiments. The embodiments described below are only preferred specific implementations of the present invention, and the protection scope of the present invention is not limited thereto. Any simple change or equivalent replacement of the technical solution that can be obviously obtained by any technician familiar with the art within the technical scope disclosed in the present invention belongs to the protection scope of the present invention.

Embodiment 1:

1) Batching: The raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _99.8 Pr _0.2. During batching, 1 wt% Pr is additionally added to compensate for burnout.

2) Melting: Use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot five times.

3) Forging: The riser and tail of the ingot are cut off and forged after grinding. The ingot is forged by one fire, three upsetting and three drawing. The single deformation is 45% and the cumulative height deformation is 270%.

4) Rolling: The ingot is ground and then rolled. The total deformation during rolling is 65%.

5) Heat treatment: The heat treatment temperature is selected to be 750°C, the heat treatment time is 1.5h, and the cooling method is air cooling.

Embodiment 2:

1) Batching: the raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _99.6 Pr _0.3. During batching, 1.5 wt% Pr is additionally added to compensate for burnout.

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot five times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged by one fire, three upsetting and three drawing, with a single deformation of 45% and a cumulative height deformation of 270%.

4) Rolling: The ingot is ground and then rolled. The total rolling deformation is 65%.

5) Heat treatment: the heat treatment temperature is selected to be 750°C, the heat treatment time is 1.5h, and the cooling method is air cooling.

Embodiment 3:

1) Batching: the raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _99.4 Pr _0.6. During batching, an additional 2 wt % Pr is added to compensate for the burnout.

2) Melting: use electron beam to melt the raw materials. Ensure that the oxygen content is ≤100ppm during melting. Repeat five times for each ingot to ensure uniformity.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged by one fire, three upsetting and three drawing, with a single deformation of 45% and a cumulative height deformation of 270%.

4) Rolling: the billet is ground and then rolled. The total rolling deformation is 65%.

5) Heat treatment: the heat treatment temperature is selected to be 750°C, the heat treatment time is 1h, and the cooling method is air cooling.

Embodiment 4:

1) Batching: the raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _99.6 Pr _0.4. During batching, 1.5 wt% Pr is additionally added to compensate for burnout.

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot five times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is subjected to two fires, six upsettings and six drawing, with a single deformation of 45% and a cumulative height deformation of 540%.

4) Rolling: the billet is ground and then rolled. The total rolling deformation is 75%.

5) Heat treatment: the heat treatment temperature is selected to be 750°C, the heat treatment time is 1.5h, and the cooling method is air cooling.

Embodiment 5:

1) Batching: the raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _99.6 Pr _0.4. During batching, 1.5 wt% Pr is additionally added to compensate for burnout.

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot five times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged twice with six upsetting and six drawing forgings, with a single deformation of 45% and a cumulative height deformation of 540%.

4) Rolling: The ingot is ground and then rolled. The total deformation during rolling is 80%.

5) Heat treatment: the heat treatment temperature is selected to be 830°C, the heat treatment time is 2h, and the cooling method is air cooling.

Embodiment 6:

1) Batching: the raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _99.2 Pr _0.8. During batching, an additional 1.5wt% Pr is added to supplement the burn loss;

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot five times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged twice with six upsetting and six drawing forgings, with a single deformation of 45% and a cumulative height deformation of 540%.

4) Rolling: The ingot is ground and then rolled. The total rolling deformation is 75%.

5) Heat treatment: The heat treatment temperature is selected as 790°C, the heat treatment time is 1.5h, and the cooling method is air cooling.

Embodiment 7:

1) Batching: the raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _98.8 Pr _1.2. During batching, 1.5wt% Pr is additionally added to supplement the burn loss;

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot five times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged twice with six upsetting and six drawing forgings, with a single deformation of 45% and a cumulative height deformation of 540%.

4) Rolling: The ingot is ground and then rolled. The total rolling deformation is 75%.

5) Heat treatment: The heat treatment temperature is selected as 750°C, the heat treatment time is 1.5h, and the cooling method is air cooling.

Embodiment 8:

1) Batching: the raw materials used are: sponge titanium (purity ≥ 99.8%), pure Pr (purity ≥ 99.5%), and the batching is based on the nominal composition of Ti _98.6 Pr _1.4. During batching, 1.5wt% Pr is additionally added to supplement the burn loss;

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot five times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged twice with six upsetting and six drawing forgings, with a single deformation of 45% and a cumulative height deformation of 540%.

4) Rolling: The ingot is ground and then rolled. The total rolling deformation is 75%.

5) Heat treatment: the heat treatment temperature is selected to be 790°C, the heat treatment time is 1.5h, and the cooling method is air cooling.

Comparative Example 1:

1) Ingredients: the raw materials used are: sponge titanium (purity ≥ 99.8%).

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot three times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged by one fire, three upsetting and three drawing, with a single deformation of 45% and a cumulative height deformation of 270%.

4) Rolling: The ingot is ground and then rolled. The total rolling deformation is 65%.

5) Heat treatment: the heat treatment temperature is selected to be 750°C, the heat treatment time is 0.8h, and the cooling method is air cooling.

Comparative Example 2:

1) Ingredients: the raw materials used are: sponge titanium (purity ≥ 99.8%).

2) Melting: use electron beam to melt the raw materials, ensure that the oxygen content is ≤100ppm during melting, and repeatedly melt the ingot three times.

3) Forging: the riser and tail of the ingot are cut off, and then forged after grinding. The ingot is forged by one fire, three upsetting and three drawing, with a single deformation of 45% and a cumulative height deformation of 270%.

4) Rolling: The ingot is ground and then rolled. The total rolling deformation is 75%.

5) Heat treatment: the heat treatment temperature is selected to be 750°C, the heat treatment time is 0.8h, and the cooling method is air cooling.

According to GB/T 228.1, experimental examples 1-8 and comparative examples were tested. To ensure the reliability of the test, 5 groups of each sample were tested and the average value was calculated. Table 1 shows the mechanical properties of the embodiments 1-8, comparative examples and the same specifications of the national standard GB/T titanium materials designed by the present invention. The obtained data are shown in Table 1.

Table 1 Summary of mechanical properties

Claims (7)

1. The Pr-doped reinforced pure titanium material is characterized in that the Pr-doped reinforced pure titanium material contains 0.01 to 1.5 weight percent of Pr, and the balance of Ti and unavoidable impurities.

2. The Pr-doped and reinforced pure titanium material according to claim 1, wherein the tensile strength of the Pr-doped and reinforced pure titanium material is 530 Mpa-660 Mpa, the yield strength is 360 Mpa-550 Mpa, and the elongation is 12% -45%.

3. A method for preparing the Pr-doped reinforced pure titanium material according to claim 1 or 2, comprising the steps of:

1) The pure titanium particles and the pure Pr particles are mixed and smelted, the atmosphere is vacuum or inert gas protection, and the oxygen content of the air during smelting is ensured to be lower than 500ppm;

2) Forging the cast ingot by upsetting, wherein the accumulated height deformation of upsetting forging is more than or equal to 120%, and the single deformation is 40% -50%; the final forging temperature is more than or equal to 650 ℃;

3) The total deformation of the thickness of the rolling is more than or equal to 60 percent;

4) Heat treating the rolled slab: the heat treatment temperature is 700-850 ℃, and the heat treatment time is 0.5-2 h.

4. The method for preparing the Pr-doped and reinforced pure titanium material according to claim 3, wherein the purity of the pure titanium particles is more than or equal to 99.5%, and the purity of the pure Pr particles is more than or equal to 99.5%.

5. The method for preparing a Pr-doped reinforced pure titanium material according to claim 3, wherein 1-3 wt% of Pr element is additionally added before smelting to compensate part of Pr element volatilized due to smelting.

6. The method for preparing a Pr-doped and reinforced pure titanium material according to claim 3, wherein in the step 1), a self-consuming smelting or an electron beam smelting is selected, and helium or argon is selected when inert gas is used as shielding gas for smelting.

7. The method for producing a Pr-doped and strengthened pure titanium material according to claim 3, wherein the ingot is repeatedly melted at least 2 times.