CN103540803A - High hardness non-magnetic nichrome and preparation method thereof - Google Patents

Abstract

The invention relates to a high-hardness non-magnetic nickel-chromium alloy and a preparation method thereof. The composition of the alloy is: Cr: 37-38, Al: 3.3-3.5, W: 1.6-2.3, Y: 0.005-0.03, C ≤ 0.015, S ≤ 0.010, P ≤ 0.010, Si ≤ 0.10, Mn ≤ 0.015, and the rest is Ni; the alloy is prepared through the steps of smelting, homogenization treatment, blanking and hot rolling, solution treatment, cold drawing and aging treatment . The nickel-chromium alloy of the present invention is obtained on the basis of ordinary high-hardness non-magnetic alloy components by appropriately adding the content of W and Y elements and reducing Cr, and the hardness of the alloy is improved through the cooperation of the cold deformation amount of the alloy and the aging temperature, And taking full account of the effects of various factors, a high-hardness non-magnetic nickel-chromium alloy with excellent performance is finally obtained.

Description

A kind of high-hardness non-magnetic nickel-chromium alloy and preparation method thereof

technical field

The invention relates to a nickel-based alloy, in particular to a high-hardness and non-magnetic nickel-chromium alloy.

Background technique

The alloy of the present invention belongs to the high elasticity alloy in the category of elastic alloy in the precision alloy field. The alloy can be used in precision machinery fields such as instruments and meters, such as shaft tips, tension wires, hairsprings, springs, springs, diaphragms and bearings, balls, stamping dies, knives, etc., and has a wide range of application backgrounds.

High-hardness, non-magnetic and high-elastic alloys include Co-based and Ni-based alloys. The current product grades mainly include: 3J21 (Co40Cr20Ni16Fe15Mo7), 3J22 (Co40Cr20Ni16Fe15Mo4W4), 3J23 (Co40Cr20Ni16Fe15Mo4W4Ce), 3YC11 (Co42Ni25Cr18Mo4W10Ce, etc.) Alloy and 3J40 (Ni55Cr40Al3.5Ce) Ni-based alloy. 3J21, 3J22, 3J23, 3YC11, and 3YC15 belong to the deformation-strengthened Co-based alloys, which must undergo a large cold deformation and then be aged to show good elastic properties. Their HRc hardness is below 65, and their χv volume magnetic susceptibility All above 400×10-6. 3J40 is a precipitation-strengthened alloy, which has good plasticity in the solid solution state. It can be strengthened to a large extent after aging treatment. Simple aging heat treatment can increase the HRc hardness of 3J40 by more than 20. 3J40's solid solution + aging and cold In the deformation + aging state, the highest HRc hardness values can reach 59 and 64 respectively, and the χv volume magnetic susceptibility is above 40×10-6. After more than 30 years of development, the above high-strength non-magnetic and high-elastic alloys have been widely used due to their good comprehensive properties. With the development of science and technology, in some special industries, higher requirements are put forward for this kind of high-strength non-magnetic elastic alloy to meet the current application requirements.

Contents of the invention

The purpose of the present invention is to propose a nickel-chromium alloy material with high hardness and low magnetism, which is accomplished through the design and optimization of alloy components.

Another object of the present invention is to provide a method for preparing the above-mentioned alloy, by adjusting the preparation process of the composition alloy to achieve the purpose of high hardness and non-magnetic properties.

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

A high-hardness non-magnetic nickel-chromium alloy. The composition of the alloy is: Cr: 37-38, Al: 3.3-3.5, W: 1.6-2.3, Y: 0.005-0.03, C≤0.015, S≤0.010 , P≤0.010, Si≤0.10, Mn≤0.015, the rest is Ni;

The alloy is prepared through the steps of smelting, homogenization treatment, blanking and hot rolling, solid solution treatment, cold drawing and aging treatment.

The metallographic structure of the alloy in service state is: fine-grained austenite matrix, precipitated γ′ strengthening phase Ni ₃ Al, α-Cr phase and trace amount of WC.

The solid solution treatment process obtains a single-phase austenite structure with fine grains.

During the solid solution treatment, spherical α-Cr phases are precipitated, and during the aging treatment, Al and Ni in the matrix produce γ′-strengthened precipitated phase Ni ₃ Al.

A preparation method of a high-hardness non-magnetic nickel-chromium alloy, comprising the steps of:

1) Batching and smelting, the composition of the alloy by weight percentage is: Cr: 37~38, Al: 3.3~3.5, W: 1.6~2.3, Y: 0.005~0.03, C≤0.015, S≤0.010, P≤0.010 , Si ≤ 0.10, Mn ≤ 0.015, the rest is Ni; vacuum induction and vacuum self-consumption dual vacuum melting is adopted, and the vacuum degree is ≤ 1×10-1Pa;

2) Homogenization annealing treatment: place the alloy ingot in a high-temperature furnace at 1100-1200°C for 0.5-2 hours;

3) Blanking and hot-rolling: When the peeling ingot is opened, it is loaded in a furnace at a temperature lower than 600°C, and after being kept at 1190-1210°C for 0.5-1 hour, it is forged into a billet, and then hot-rolled at 1190-1210°C for 0.5-1 hours. disk circle;

4) Solution treatment: heat preservation at 1180-1200°C for 20-60 minutes, and rapidly quench water to obtain a single-phase austenite structure with fine grains;

5) Cold drawing: the disc is cold deformed to obtain a product with no scratches on the surface of the required size;

6) Aging treatment: the cold-drawn bar is kept at 500-625°C for 4-5 hours.

The solid solution treatment process obtains a single-phase austenite structure with fine grains.

During the solid solution treatment, spherical α-Cr phases are precipitated, and during the aging treatment, Al and Ni in the matrix produce γ′-strengthened precipitated phase Ni ₃ Al.

The deformation in the cold drawing step is 75%-90%.

Based on the above purpose, we adopt Ni-38Cr-3Al-W as the main component in the composition design of the alloy. The alloy is based on Ni and Cr, and an appropriate amount of Al can precipitate face-centered cubic γ' strengthening phase (Ni ₃ Al) during aging heat treatment with matrix Ni, and precipitate spherical α-Cr phase during solid solution treatment. An appropriate amount of W is dissolved in the matrix and a small amount of WC is precipitated. These factors combine to increase the hardness of the alloy. The content of Cr, W, and Al is closely related to the processing performance of the alloy. With the increase of the element content in the alloy, the brittleness of the alloy is significantly enhanced. , which is not conducive to the processing and application of the alloy; with the reduction of the content of alloying elements, the plasticity of the alloy is significantly enhanced, which is beneficial to the processing and application of the alloy, but the strength and hardness are significantly reduced. The change of Al content will affect the solid solution temperature of the alloy, and the increase of the content will increase the solid solution temperature of the alloy, and Al participates in the aging precipitation behavior during the aging process, so an appropriate amount of Al content is particularly critical. As a solid solution strengthening element, W participates in the aging precipitation behavior at the same time, increasing the strength and hardness of the alloy. If the W content is too high, the processing performance of the alloy will be reduced. As an alloy purifying element, Y can effectively reduce the content of impurity elements in the alloy. According to the function of each element in the alloy, the present invention requires reasonable allocation, properly reduces the Cr content when designing the alloy composition, and at the same time adds W, Y and other alloying elements in an appropriate amount to make the alloy have unique comprehensive properties. The composition of the alloy of the present invention should be controlled in (weight%) Cr: 37-38, Al: 3.3-3.5, W: 1.6-2.3, Y: 0.005-0.0.03, C≤0.015, S≤0.010, P≤0.010, Si≤0.10, Mn≤0.015, and the rest are Ni.

In order to obtain a NiCr alloy with high hardness and low magnetism, in addition to the alloy composition, to ensure the performance of the alloy, it is necessary to adopt appropriate alloy preparation methods such as processing technology and heat treatment technology.

Prepare the high-hardness non-magnetic nickel-chromium alloy of the present invention through the following steps:

1. Melting

Before smelting the alloy, the oxide layer on the surface of the metal Ni should be polished and removed. Alloy smelting must go through vacuum induction and vacuum self-consumption dual vacuum, the vacuum degree is ≤1×10-1Pa, and the burning loss of alloy elements must be strictly controlled during the smelting process.

2. Homogenization treatment

The alloy ingot is placed in a high-temperature furnace for long-term homogenization annealing treatment. After the treatment, the skin is peeled off and the chemical composition of the alloy is analyzed by sampling.

3. Billet opening and hot rolling

When the peeled ingot is opened, it is lower than 600 ℃ and the furnace is loaded. The size of the alloy ingot determines the speed of the alloy ingot’s heating up. Then heat it at 1190-1210°C for an appropriate time and then hot-roll it into a disc.

4. Solution heat treatment

The disc-shaped solid solution heat treatment temperature is 1180-1200°C, the temperature is kept for 20-60 minutes, and the water is rapidly quenched to obtain a single-phase austenite structure with fine grains. Under the condition of ensuring complete solid solution, the lower solid solution temperature should be selected as much as possible.

5. Cold drawn

The bright rods are cold drawn to the required size by different cold deformation. During the cold drawing process, pay attention to the choice of lubricant and the amount of deformation in each pass, so that there are no scratches on the surface.

6. Aging treatment: After the cold-drawn bar is processed into the required parts, it is kept at 500-625°C for 4-5 hours for aging heat treatment.

The NiCr alloy involved in the present invention is based on the composition of ordinary high-hardness non-magnetic alloy (domestic brand 3J40), and the content of W and Y elements is appropriately added to reduce Cr and improve the hardness of the alloy. The temperature adjustment adjusts the hardness of the alloy. The NiCr alloy involved in the present invention fully considers the effects of various factors, and finally prepares a high-hardness non-magnetic NiCr alloy with excellent performance.

Description of drawings

Figure 1 shows the hardness of the solid solution alloy rod after cold drawing at 550°C, 575°C, 600°C, and 625°C×5h in the embodiment of the present invention. ;

Fig. 2 is the magnetic susceptibility of embodiment alloy among Fig. 1;

Fig. 3 is the hardness of the sample of the embodiment alloy in Fig. 1 through cold drawing reduction and 500 ℃ of aging treatment;

FIG. 4 is the magnetic susceptibility of the example alloy in FIG. 3 .

Detailed ways

The present invention will be described in detail below in conjunction with the embodiments.

1. Use a 25Kg vacuum induction furnace to melt 2 (1#, 2#) vacuum consumable electrode ingots (size: Φ80mm), and prepare two components of vacuum consumable electrodes after the consumable ingots are turned and flattened. Table 1 shows the composition comparison of high-hardness non-magnetic NiCr alloy steel ingots after vacuum self-consumption and mature brand products:

Table 1 alloy composition

2. The alloy ingot is homogenized annealed at 1200°C for 1 hour, then forged into a billet at 1180°C for 1 hour, and the billet is hot-rolled into a Φ10mm disc after being held at 1180°C for 1 hour, and the disc is kept at 1200°C for 20 minutes After solid solution treatment, water is quenched to obtain a solid solution state alloy disc, and the disc is straightly polished to obtain a Φ9.5mm straight NiCr alloy rod.

3. After cold-drawing solid solution alloy rods, aging treatments were performed at 550°C, 575°C, 600°C, and 625°C×5h respectively. The properties of the obtained solid solution + aging alloys are shown in Figures 1 and 2.

4. The diameter of the Φ9.5mm solid solution alloy is reduced by cold drawing. During the cold drawing process, pay attention to the choice of lubricant and pass deformation to ensure that there is no scratch on the surface. The performance of the sample subjected to aging treatment at 500°C is shown in Figures 3 and 4.

A high-hardness non-magnetic nickel-chromium alloy with excellent properties was prepared by optimizing the alloying elements and matching the appropriate preparation process. The hardness of the developed alloy in the solid solution aging state is HRc > 60.5, up to 62, the hardness in the cold deformation aging state is HRc > 65, up to 67.5, and the volume magnetic susceptibility < 28×10 ^-6 .

Claims (8)

1. high rigidity, without a magnetic nichrome, is characterized in that, the composition of this alloy is by weight percentage: Cr:37～38, Al:3.3～3.5, W:1.6～2.3, Y:0.005～0.03, C≤0.015, S≤0.010, P≤0.010, Si≤0.10, Mn≤0.015, all the other are Ni;

This alloy is prepared by smelting, homogenizing processing, cogging and hot rolling, solution treatment, cold drawn and ageing treatment step.

2. high rigidity according to claim 1, without magnetic nichrome, is characterized in that, described this alloy in the metallographic structure of the state of use is: the austenitic matrix that crystal grain is tiny and the γ ' strengthening phase Ni separating out ₃the WC of Al, α-Cr phase and trace.

3. high rigidity according to claim 2, without magnetic nichrome, is characterized in that, described solution treatment obtains the single-phase austenite structure that crystal grain is tiny.

4. high rigidity according to claim 1, without magnetic nichrome, is characterized in that, separates out globular α-Cr phase in described solution treatment process, and in ageing treatment process, the Ni of Al and matrix produces γ ' strengthening precipitated phase Ni ₃al.

5. the preparation method of the non-magnetic nichrome of high rigidity as claimed in claim 1, is characterized in that, comprises the steps:

1) batching melting, the composition of this alloy is by weight percentage: Cr:37～38, Al:3.3～3.5, W:1.6～2.3, Y:0.005～0.03, C≤0.015, S≤0.010, P≤0.010, Si≤0.10, Mn≤0.015, all the other are Ni; Adopt vacuum induction and the vacuum melting of vacuum consumable duplex, vacuum tightness≤1 * 10-1Pa;

2) homogenizing annealing is processed: alloy pig is placed in to High Temperature Furnaces Heating Apparatus and at 1100-1200 ℃, is incubated 0.5-2 hour;

3) cogging, heat are pricked: while stripping off the skin ingot cogging, lower than 600 ℃ of shove charges, through 1190～1210 ℃ of insulations, after 0.5-1 hour, be forged into square billet, then after 1190～1210 ℃ of insulation 0.5-1, be rolled into dish circle;

4) solution treatment: be incubated 20～60 minutes at 1180～1200 ℃, hardening, obtains the tiny single-phase austenite structure of crystal grain rapidly;

5) cold drawn: dish circle obtains the surperficial no marking product of desired size through cold deformation;

6) ageing treatment: the bar after cold drawn is incubated 4-5 hour at 500-625 ℃.

6. preparation method according to claim 5, is characterized in that, described solution treatment obtains the single-phase austenite structure that crystal grain is tiny.

7. preparation method according to claim 5, is characterized in that, separates out globular α-Cr phase in described solution treatment process, and in ageing treatment process, the Ni of Al and matrix produces γ ' strengthening precipitated phase Ni ₃al.

8. preparation method according to claim 5, is characterized in that, the deflection of described cold drawn step is 75%-90%.

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