JPH0621308B2 - Non-heat treatment type rapidly solidified aluminum alloy for mold materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a non-heat treatment type rapidly solidified aluminum alloy for a die material having high hardness and strength.

[Prior Art] Recently, an aluminum wrought alloy 7075-T651 has been adopted as a material for a mold because of its light weight, corrosion resistance, free-cutting property, hardness and high strength. Thickness 50 for mold material
In many cases, materials with a size of mm or more are used, and there is a difference in cooling rate between the surface and the inside of the material during quenching during T651 treatment.
The inside was softer and weaker than the surface.

Further, residual stress was generated due to the difference in cooling rate, which was released during the cutting work and deformed the material. The thicker and larger the die material, the larger the cooling rate difference between the surface and the interior during quenching, so the deformation due to the cutting process became large, and cracks occurred in the material with low ductility. Therefore, although the solutionizing temperature was lowered or the water was quenched, the cooling rate difference between the surface and the inside was reduced, but the cooling rate was low overall, so as shown in Table 1, strength and hardness were sacrificed. I was doing.

[Problems to be Solved by the Invention] In the present invention, various investigations have been made on materials that can be used for a mold in a non-heat-treated state. Attention was paid to (1) to 108338). This alloy is excellent in tensile strength, fatigue strength and notch fatigue strength even after T6 treatment. However, according to subsequent property investigation, this alloy shows that hardness, tensile strength, heat resistance and resistance to heat resistance are high even in the non-heat treatment state. It was found that it is suitable as a mold material because it has better wear resistance than the 7075-T651 material. It is especially suitable for thick and large molds and when used under high temperature and high pressure. Further, it has a high modulus of longitudinal elasticity and a low coefficient of linear expansion, and in this respect, it is also suitable as a mold material. Further, since the ductility is high, cracks do not occur even when formed into a shape in which stress is easily concentrated.

The present invention provides a non-heat treatment type rapidly solidified aluminum alloy for a die material having high hardness and strength based on the above findings.

[Means for Solving the Problems] The present invention is based on weight: Fe: 6-10%, Si: 2.6-
10%, Cu: 1-6%, Mg: 0.3-3% and V:
0.5-5%, Mo: 0.5-5%, Zr: 0.4-4
% Non-heat treatment type rapidly solidified aluminum alloy for die materials, which has a composition of 8% or less in total of 1% or 2% or more, and is used in a non-heat treatment state.

The reasons for limiting each component in the present invention are as follows.

Fe: Al ₃ Fe, Al ₆ Fe, Al-Fe metastable phase or Al-
Disperses as a Si-Fe compound to enhance tensile strength, heat resistance, fatigue strength and notch fatigue strength. It also has the effect of increasing the elastic coefficient and decreasing the linear expansion coefficient. If the amount is less than 6%, the effect is insufficient, and if it exceeds 10%, the ductility is insufficient and hot working becomes difficult.

Si: coexist with Fe and dispersed as an Al-Fe-Si compound,
Increases ductility, fatigue strength and notch fatigue strength. It also increases the elastic coefficient and lowers the linear expansion coefficient. If the amount is less than 2.6%, the amount of Al-Si-Fe compound is insufficient, and the ductility, fatigue strength,
Notch fatigue strength becomes low. Also, if it exceeds 10%, Al-Si
Since the Fe-based compound becomes coarse, the ductility and notch fatigue strength become low.

Coexists with Cu: Mg and imparts age hardening. However, age hardening is performed by air cooling after hot working and room temperature aging.
Age hardening improves tensile strength, fatigue strength, and notch fatigue strength. If the amount is less than the lower limit, the effect is not sufficient, and if it exceeds the upper limit, the ductility reduces the corrosion resistance.

Coexists with Mg: Cu and imparts age hardenability. Age hardening improves tensile strength, fatigue strength and notch fatigue strength.
If the amount is less than the lower limit, the effect is not sufficient, and if it exceeds the upper limit, the effect is saturated.

V, Mo: Co-exist with Fe and dispersed as an Al-Fe-V, Al-Fe-Mo or Al-Fe-V-Mo based compound to improve tensile strength and fatigue properties, especially strength at high temperature. If the amount is less than the lower limit, the effect is not sufficient, and if it exceeds the upper limit, the effect is saturated and the cost increases.

It forms a Zr: Al-Zr compound to improve tensile strength and fatigue strength. Also, Al-Fe, Al-Fe-V, Al-Fe-Mo
Alternatively, it suppresses coarsening of Al-Fe-V-Mo compounds.
If the amount is less than the lower limit, the effect is not sufficient, and if it exceeds the upper limit, the effect is saturated and the cost increases.

V + Mo + Zr: When it exceeds 8%, not only the effect is saturated, but also the ductility is impaired.

In order to manufacture a die material using the alloy of the present invention, the aluminum alloy having the composition of the present invention is melted, and then the molten metal is rapidly solidified. Usually, it is cooled at a cooling rate of 100 ° C / sec or more. Specifically, the atomization method, the splat cooling method, or the spray deposition method is applied. The molding method of the powder manufactured by the atomizing method or the splat cooling method is shown below.

(a) Pre-compression ... Heating vacuum degassing-extrusion (b) Pre-compression ... Heating vacuum degassing-hot pressing (c) Pre-compression ... Heating vacuum degassing-hot pressing-container removal-extrusion (d) Pre-compression ... heating It is molded and solidified by a process such as vacuum degassing-HIP (high temperature isostatic pressing). Specifically, in the step (a), the aluminum alloy powder is pre-compressed to about 60 to 90% of the true density by CIP or die compression, and then 300 to 550.
Degas by evacuation while heating to ℃. If the heating temperature during degassing is less than 300 ° C, the degassing will be insufficient and the final product will swell and have pores. When it exceeds 550 ° C, Si particles grow and become a raw material. The preliminary compressed body (billet) thus degassed is heated to a temperature of 300 to 520 ° C. and extruded. The quality does not change even if pre-compression is omitted. Vacuum sealing during degassing and hot working is performed by charging a powder container and sealing jigs and tools.

The method (b) is hot pressing (300 to 550 ° C) instead of extrusion.
The billet is densified by upsetting and compressing), (c) is hot-pressed and then the container is cut off and extruded, and (d) is pre-compressed in air, in vacuum or under N ₂ , A
A material which is heated in a gas such as r to be degassed and then extruded, and (e) is one which obtains an aluminum alloy material by HIP treatment instead of extrusion or hot pressing.

If the mold size is large and you need large size material,
After being solidified and molded by the hot pressing of (b) and HIP of (e), it is extended by forging and rolling to obtain a large-sized material.

[Examples] Alloys Nos. 1 to 15 shown in Table 2 were melted and rapidly solidified powder was prepared by air atomization. The resulting powder has a particle size of 29
After dispersing to 7 μm or less, the true density is 70-75 by CIP.
%, Precompressed to%, charged into an aluminum container and evacuated while heating. The heating temperature was 500 ° C. The billet thus obtained was heated to 390 ° C. and indirectly extruded at an extrusion ratio of 14 to obtain a bar having an outer diameter of 40 mm.

As for No. 16 alloy in Table 2, an ingot having an outer diameter of 150 mm was prepared after melting and extruded under the same conditions as above. Extrusion rod 465 ℃ × 1hr → Water cooling → Tension of 2% permanent strain → 120 ℃ × 24h
The heat treatment (T651 treatment) was performed under the condition of r → cooling.

Regarding the above materials, room temperature hardness after room temperature heating 200 ℃, room temperature tensile strength, room temperature tensile strength, tensile strength at 200 ℃ after holding at 200 ℃ for 100 hours, wear depth of the disk in pin disk wear test, residual The stress, Young's modulus and linear expansion coefficient were measured.

The results are shown in Table 3. Table 3 is for a thickness of 50 mm.

The invention alloy has higher hardness, higher tensile strength at room temperature and 200 ° C., and higher wear resistance than 7075-T651 (comparative alloy N0.16), and has sufficiently high elongation at room temperature and 200 ° C.

Among the comparative alloys, No. 10 has no added V, Mo and Zr, and No. 11 has a small amount of Fe, and thus has low hardness and low tensile strength. No. 12 has a large amount of Fe and thus has poor ductility. No.
13 has a large amount of Si and thus has poor ductility. Since No. 14 has a small amount of Cu, hardness and tensile strength at room temperature are low. No.15 is V
Since + Mo + Zr content exceeds 8%, ductility is poor.

[Effects of the Invention] According to the present invention, a die material having better hardness, tensile strength, and wear resistance than the 7075-T651 material in a non-heat-treated state can be obtained. Therefore, it is possible to solve the problem that the surface of the large-sized 7075-T651 material is harder than the inside thereof and is strong, and that strain occurs due to residual stress release during cutting. The mold of the present invention is 150 to 200 ° C more than 7075-T651 material.
It is advantageous when the molding temperature is high and the molding temperature is high like SMC (Silicon Mold Compound).

Objects to be molded using the mold of the present invention include a wide range of objects such as resin, rubber, metal powder, and ceramic powder.

Claims (1)

[Claims] 1. Fe: 6-10%, Si: 2.6-10 by weight
%, Cu: 1-6%, Mg: 0.3-3% and V: 0.5-5%,
Mo: 0.5-5%, Zr: 0.4-4%, 1 type or 2 or more types, having a total composition of 8% or less, and being used in a non-heat-treated state, non-heat-treated rapid cooling for die materials. Solidified aluminum alloy.