JPH03236452A - Production of forged wheel made of magnesium alloy - Google Patents

Abstract

PURPOSE:To prevent cracking and to obtain a forged wheel excellent in mechanical strength by applying heating and forging to a stock for an Mg alloy containing Zn and Zr, exerting spinnings including reheating between the spinning stages, and then carrying out heat treatment and machining. CONSTITUTION:A stock for an Mg alloy having a composition containing, by weight, 4.8-6.2% Zn, 0.45-5.0% Zr, and inevitable impurities is heated and subjected to preforging and finish forging. This stock is heated and subjected to primary spinning and is further reheated and subjected to secondary spinning. Subsequently, the prescribed heat treatment and machining are carried out, by which the forged wheel made of Mg alloy is obtained. This forged wheel is used for aircraft and automobile uses. It is preferable to regulate heating temp. for the stock before preforging, forging die temp. at the time of forging, and average working strain velocity to about 180-430 deg.C, about 200-350 deg.C, and about 10<-1>-10 deg.C/sec, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a magnesium alloy (hereinafter referred to as "Mg alloy") 8-frame wheel used, for example, for aircraft or automobiles.

(Prior art) Currently, iron or AI wheels are mainly used for aircraft and automobile wheels that are in practical use.
Furthermore, the need for weight reduction has increased from the perspective of energy saving, and lighter Mg alloy wheels have been attracting attention.

However, even though the need for weight reduction has increased, it is still small compared to the need for steel or AI wheels, and the shape of the wheel is complex, so most of the Mg alloy wheels currently in production are made by casting. Manufactured.

(Problems to be Solved by the Invention) However, when producing ceramic alloy wheels by casting, the yield rate is extremely low due to the difficulty of the casting method, and internal defects due to the casting product cause the following problems. As shown in Table 1, both strength and reliability as a product were low.

Table 1 The present invention aims to provide a method for manufacturing a forged Mg alloy wheel that can solve the above-mentioned problems.

(Means for Solving the Problems) In order to achieve the above object, the present inventors conducted various forging tests and established a method for manufacturing a practically usable Mg alloy forged wheel.

That is, in the method for manufacturing a ceramic alloy forged wheel according to the present invention, Zn: 4.8 to 6.2%, Zr: 0 in weight%.
．． After heating the Mg alloy material containing 45% to 5.0% and unavoidable impurities, preliminary forging and finishing forging are performed, then primary spinning processing is performed after heating the material, and then the material is recycled. The gist of this is to perform a secondary spinning molding process by heating, and then to perform predetermined heat treatment and mechanical processing.

In that case, the heating temperature of the material before preliminary forging is 1
80-430℃ 1 The mold temperature during preliminary forging and finish forging is 200-350℃ and the average processing strain rate is 10-I ~
It is preferable to set it as 100/sec.

Furthermore, the material heating temperature before the primary spinning forming process and before the secondary spinning forming process is 180 to 430°C1.
It is preferable that the mandrel temperatures during the primary and secondary spinning forming processes are respectively 300 to 350°C.

In the present invention, the heating temperature of the material before pre-forging, primary spinning, and secondary spinning is set at 180 to 430°C because the deformation resistance of the material is extremely high below 180°C, and This is because cracks occur during molding.

On the other hand, even if the temperature exceeds 430°C, cracks will occur during molding.

In addition, in the present invention, the temperature of the forming die during preliminary forging and final forging was set at 200 to 350°C, because if the temperature is less than 200°C, the material temperature will be taken over by the die during the forming time. This is because molding becomes difficult for these reasons. On the other hand 35
This is because if the temperature exceeds 0°C, the mold temperature will rise during continuous operation, exceeding the upper limit of the optimum material heating temperature, and causing cracks in the material during material molding.

In addition, in the present invention, the average working strain rate during preliminary forging and finish forging is set to 10-' to 10'/sec.
If it is less than 10-'/sec, it will take a long time to mold, during which time the temperature of the material will drop, making molding difficult for the reasons mentioned above. On the other hand, if it exceeds 100/sec, the temperature of the material increases due to material processing during molding, and there is a risk that the optimum material processing temperature may be exceeded.

In addition, in the present invention, the mandrel temperature during the primary and secondary spinning forming processing was set at 300 to 350°C.
This is because if it is less than 00"C, the material temperature will be taken over by the mandrel during the forming time, making forming difficult for the reasons mentioned above. On the other hand, if it exceeds 350"C, the mandrel temperature will rise during continuous operation and the upper limit of the optimum material temperature will be reached. This is because the material exceeds this limit and cracks occur in the material during material molding.

In the present invention, the heating temperature of the material before finish forging is not specified because the steps from preliminary forging to finish forging can be performed in one heating process, thereby simplifying the process.

(Function) According to the method of the present invention described above, it is possible to manufacture a Mg alloy forged wheel that suppresses the occurrence of cracks as much as possible, has a high yield rate, and has excellent strength.

(Example) An example of the method of the present invention will be described below based on the process diagram shown in FIG.

First, a ZK60A alloy with dimensions of 200 mm in diameter and 320 mm in length and the chemical composition shown in Table 2 below was heated at 390°C±lO.
℃ and held for over 4 hours.

Table 2 Table 3 (Unit double weight %) Then, after that, the mold temperature was maintained at 200 to 350'' and the average C1 processing strain rate was 10-1 to 10'/sec, and preliminary forging and finishing forging were carried out. went.

After that, the first spinning forming process and the second spinning forming process are performed sequentially, but before these spinning forming processes, the material is heated to a temperature of 390±10"C and held for 5 minutes, and the mantle during the spinning forming process is heated. 300″C
After heating, molding was performed.

Immediately after the secondary spinning molding process, it was cooled with water for 15 minutes.
It was maintained at a temperature of 0±5° C. for 24 hours, then air-cooled (heat treated), and machined into the shape shown in FIG.

When the mechanical properties of the ceramic alloy forged wheel manufactured by the method of the present invention were investigated, the results were as shown in Table 3 below.
It was confirmed that this wheel is superior to conventional cast wheels (see Table 1).

In addition, as a result of investigating the crack growth rate, as shown in Fig. 3, results were obtained that showed no discoloration compared to cast products.

Furthermore, when the method of the present invention was carried out, the yield rate was 98%, which was significantly improved compared to the 30-40% yield rate when the wheel was forged and manufactured under the same conditions as the A1 wheel.

(Effects of the Invention) As explained above, according to the method of the present invention, forged products can be manufactured with a high yield rate, without discoloration compared to cast products even when cracks grow, and whose mechanical properties are superior to cast products. becomes possible.

[Brief explanation of drawings]

Fig. 1 is a process diagram of the method of the present invention, Fig. 2 is a diagram showing an example of the shape of a forged Mg alloy wheel manufactured by the method of the present invention,
FIG. 3 is a diagram showing the results of the crack growth rate of the products manufactured according to the present invention. No.: 2nd ward, 3rd edition, ed./ed.)

Claims (3)

[Claims] (1) In weight%, Zn: 4.8 to 6.2%, Zr: 0.
After heating the magnesium alloy material containing 45% to 5.0% and unavoidable impurities, preliminary forging and finishing forging are performed, then primary spinning processing is performed after heating the material, and then the material is recycled. A method for producing a forged magnesium alloy wheel, which comprises heating and performing a secondary spinning forming process, followed by predetermined heat treatment and machining. (2) Material heating temperature before preliminary forging is 180 to 430
℃, mold temperature during preliminary forging and finish forging is 200~
350℃ and average processing strain rate 10^-^1~10^0
2. The method for manufacturing a forged magnesium alloy wheel according to claim 1, wherein: /sec. (3) Material heating temperature before preliminary forging, primary spinning forming, and secondary spinning forming is 180°C.
3. The method for producing a forged magnesium alloy wheel according to claim 1, wherein the mandrel temperature during the primary and secondary spinning forming processes is 300 to 350C, respectively.