JPH0657360A - Corrosion resistant and wear resistant ni-base alloy - Google Patents

Abstract

PURPOSE:To produce an Ni-base allay excellent in corrosion resistance and wear resistance and useful as the constituting material for a cylinder, screw or the like of an injection molding machine, etc. CONSTITUTION:This Ni-base alloy is constituted of 5 to 20% Cr, 7 to 30% Mo, 0.5 to 30% of one or two kinds of W and V, 0.1 to 6% B, 0.5 to 3% Si and 1.5% or less C, and the balance being substantially Ni. If desired, the chemical compsn. contg. 0.5 to 15% Co or/and 2 to 10% Fe is given thereto for the purpose of improving its toughness.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is useful as a constituent material for various members that require corrosion resistance and wear resistance, such as cylinders, screws and plungers of injection molding machines and extrusion molding machines.
It relates to an i-based alloy.

[0002]

2. Description of the Related Art Cylinders constituting injection molding machines and extrusion molding machines, and members such as screws and plungers are required to have wear resistance and corrosion resistance against contact of fluids which are fed under high pressure and high speed. . Conventionally, nitrided steel (JIS G4202, SACM645, etc.) has been exclusively used as the material.

[0003]

The effective nitriding layer thickness on the surface of nitrided steel is only about 0.5 mm, and therefore the durability of conventional injection molding machines and extrusion molding machines using nitrided steel is improved. Is not always sufficient. In particular, recently, the demand for fiber-reinforced plastic molded products, plastic magnets, ceramic molded products, etc. has been increasing. The decrease in life is remarkable, and it is extremely difficult to deal with it as a production machine. As a measure against this, Japanese Patent Laid-Open No. 1-27273
No. 2 publication, Cr: 5 to 20%, Mo: 5 to 20%,
W: 5-15%, B: 0.5-4%, Si: 0.5-3
%, C: 1.5% or less, the balance being Co, and a Co-based alloy having improved corrosion resistance and wear resistance is disclosed. However, Co is a strategic material, is expensive, and is unstable. Therefore, the present invention provides a Ni-based alloy having a novel chemical composition in which a part or all of Co is replaced with Ni and having high corrosion resistance and high wear resistance.

[0004]

Means and Actions for Solving the Problems Corrosion-resistant and wear-resistant Ni-based alloys of the present invention are Cr: 5-20%, Mo: 7-
30%, B: 0.1 to 6%, one of W and V or 2
Species: 0.5-30%, Si: 0.5-3%, C: 1.5
% Or less, and the balance has a chemical composition substantially consisting of Ni. If desired, the Ni-based alloy of the present invention is provided with a chemical composition containing one or both of Co: 0.5 to 15% and Fe: 2 to 10% in addition to the above elements.

The reasons for limiting the components of the Ni-based alloy of the present invention are as follows. Cr: 5 to 20% Cr partly forms a solid solution in the matrix to improve the corrosion resistance of the alloy, and the balance forms carbides and borides to increase the hardness of the alloy and enhance the wear resistance. The reason why the lower limit of the content is 5% is that these effects are insufficient with a smaller amount, and the effect increases as the amount increases. In particular, when it is necessary to strengthen the corrosion resistance, the Cr content should be [1.4
2 (B + 1 / 2C) +11.9] (%) or more Cr
It is recommended to enrich the solid solution amount of. The effect is almost saturated when the content is up to 20%, so this is the upper limit.

Mo: 7 to 30% Mo forms carbides and borides to enhance the wear resistance of the alloy, and Mo which forms a solid solution in matrix without forming carbides and borides is corrosion resistant, especially It contributes to the improvement of corrosion resistance to non-oxidizing acids such as hydrochloric acid. In order to obtain these effects, it is necessary to contain at least 7%. In particular, when it is necessary to enhance the corrosion resistance, the content is [4.7
(B + 1 / 2C) +7] (%) or more, and the solid solution amount of Mo may be increased. However, if the Mo content is too large, the alloy becomes brittle, so the upper limit is 30%.

W, V: 0.5 to 30% W and V have the effects of forming carbides and borides, respectively, and increasing the hardness and wear resistance of the alloy. These two elements may be used either alone or in combination of both. This effect is obtained by containing 0.5% or more (the total amount in the case of complex addition), and the effect increases as the content increases. However, if added in a large amount, the bending strength and toughness of the alloy are deteriorated, so the upper limit is 30% (the total amount in the case of compound addition).

B: 0.1-6% B requires at least 0.1% for the formation of borides such as Cr, Mo, W, V. Further, the addition of B lowers the melting point of the alloy without impairing the corrosion resistance and makes the melting operation of the alloy advantageous. However, if it exceeds 6%, the toughness is remarkably reduced, so 6% should not be exceeded. In addition, it is preferable that the total amount of the B content and the C content (B + C) is 6% or less from the viewpoint of ensuring the toughness of the alloy.

Si: 0.5 to 3% Si forms a compound with elements such as Cr, Mo, W and V, and contributes to improvement of wear resistance of the alloy. Further, the melting point of the alloy is lowered due to the inclusion of Si, which is advantageous for the melting operation of the alloy. To obtain these effects, at least 0.
A content of 5% is required. However, if it is contained in a large amount exceeding 3%, the alloy becomes brittle and the usefulness as a structural material is impaired, so this was made the upper limit.

C: 1.5% or less C is an element necessary for forming carbides such as Cr, Mo, W and V, and lowers the melting point of the alloy to make the alloy melting operation advantageous. However, if the content exceeds 1.5%, the alloy becomes brittle and the usefulness as a structural material is impaired.
1.5% or less.

Co: 0.5 to 15% Co is an element effective for improving the toughness of the alloy. The effect is obtained by adding 0.5% or more. However, addition of a large amount not only impairs economic efficiency but also reduces corrosion resistance, particularly corrosion resistance to hydrofluoric acid, so the upper limit is 15%. It is preferably 5 to 12%.

Fe: 2 to 10% Fe is effective in improving the toughness of the alloy. To obtain this effect, it is necessary to contain at least 2%. However, if added in a large amount, the corrosion resistance is deteriorated, so the content is limited to 10%.

The Ni-based alloy of the present invention uses, for example, the alloy powder as a sintering raw material and is subjected to a known sintering process such as hot isostatic pressing under the isostatic pressure to produce a mother material for cylinders, screws and the like. A sintered alloy layer that covers the surface of the material metal is formed. Further, when the B content is set to be relatively high, it becomes easy to apply a melting / solidifying process instead of the sintering process by lowering the melting point of the alloy.
When the composition of the low melting point component is about 1150 ° C. or less, the ordinary steel materials (SS41 material, for example) are used as the base metal, and the low melting point alloy powder is applied to the surface of the base metal to melt and solidify the powder. It is also possible to stack and form a dense alloy layer metallurgically bonded to the surface of the material without causing melting loss of the material.

[0014]

[Example] For each match shown in Table 1, a corrosion test,
A wear test and a mechanical test were performed and the results shown in Table 2 were obtained. Matching funds Nos. 1 to 7 are inventive examples, Nos. 21 to 25 are comparative examples, and Comparative examples Nos. 21 to 23 are the same as those disclosed in the above-mentioned JP-A-1-.
Co-based alloy equivalent material disclosed in Japanese Patent No. 272732, N
o.24 is an example of a Co-based alloy in which W and B are set to be slightly lower, and No. 25 is a nitrided steel (JIS G4202 SACM
645, surface nitrided layer thickness 0.5 mm).

The test procedures are as follows. [I] Corrosion test The test piece was immersed in the following four kinds of corrosive liquids (liquid temperature: 50 ° C),
The corrosion weight loss (g / m ² hr) after 48 hours is measured. Test A: 10% hydrofluoric acid aqueous solution Test B: 10% hydrobromic acid aqueous solution Test C: 20% hydrochloric acid aqueous solution Test D: 50% sulfuric acid aqueous solution

[II] Abrasion test Using an Ogoshi type rapid abrasion tester, the abrasion loss (mm ² / kgf) is measured by the following abrasion test. (1) Counterpart material (rotating wheel): SUJ2, hardness (H _RC ): 5
8-60 (2) Pressing load: 6.3 kg / cm ² (3) Sliding contact speed: 1.93 m / sec (4) Sliding contact distance: 400 m

As shown in Table 2, Invention Examples No. 1 to 7
Has significantly better corrosion resistance to various acids and wear resistance than nitrided steel (No. 25). From the comparison between Invention Examples No. 2 and No. 6, it can be seen that the toughness improving effect by the addition of Co is obtained, and the comparison between No. 6 and No. 7 also shows the toughness improving effect by the addition of Fe. Inventive examples Nos. 1 to 7 were N-based alloys based on Co.
Compared with o.21 to 24, the corrosion resistance to 50% sulfuric acid (Table 2, column "D") is slightly lower, but the corrosion resistance to 10% hydrofluoric acid (column "A") is clearly superior. Therefore, it is understood that other corrosive acids have equivalent corrosion resistance.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

Since the Ni-based alloy of the present invention has wear resistance and corrosion resistance that greatly surpass those of nitrided steel and the like, it can be used as a material for cylinders, screws and plungers of injection molding machines and extrusion molding machines. Its service life can be improved, and it contributes not only to ordinary plastic molding, but also to stabilization and efficiency of injection / extrusion molding operations for fiber reinforced plastics, ceramics and the like. It is also advantageous in terms of stability of raw material supply and cost as compared with Co-based alloys.

Claims (4)

[Claims] 1. Cr: 5-20%, Mo: 7-30%,
One or two kinds of W and V: 0.5 to 30%, B: 0.
1 to 6%, Si: 0.5 to 3%, C: 1.5% or less, and a corrosion- and wear-resistant Ni-based alloy consisting essentially of the balance Ni. 2. Cr: 5 to 20%, Mo: 7 to 30%,
One or two kinds of W and V: 0.5 to 30%, B: 0.
1 to 6%, Co: 0.5 to 15%, Si: 0.5 to 3
%, C: 1.5% or less, a corrosion- and wear-resistant Ni-based alloy consisting essentially of the balance Ni. 3. Cr: 5-20%, Mo: 7-30%,
One or two kinds of W and V: 0.5 to 30%, B: 0.
1 to 6%, Fe: 2 to 10%, Si: 0.5 to 3%,
C: Corrosion-resistant and wear-resistant Ni-based alloy with C: 1.5% or less and the balance being substantially Ni. 4. Cr: 5-20%, Mo: 7-30%,
One or two kinds of W and V: 0.5 to 30%, B: 0.
1 to 6%, Co: 0.5 to 15%, Fe: 2 to 10%,
A corrosion- and wear-resistant Ni-based alloy having Si: 0.5 to 3%, C: 1.5% or less, and the balance being substantially Ni.