JPS585966B2 - Maraging process - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming maraging steel sheets.

Generally, press working is carried out at room temperature, but when maraging steel sheets are formed by ordinary methods, the deformation becomes significantly large.

Conventionally, deformations such as warpage and twisting have been removed using so-called thermal straightening, which involves fixing the material with jigs and heating it in a post-process, but it is extremely difficult to completely straighten the material.

The purpose of the present invention is to provide a maraging steel plate that reduces the amount of deformation during press forming or minimizes the amount of deformation to facilitate straightening, in order to solve the problems of the conventional press forming method described above. To provide a press molding method.

The present invention focuses on the fact that even if there is anisotropy, a maraging steel sheet molded product with a small amount of deformation such as warping can be obtained by forming in a state with low yield strength. Aging type in which special materials such as Mo, At, and Ti are added to Fe-Ni alloy for the purpose of increasing strength in a temperature range from Mf point, which is the temperature at which 100% transformation from the structure to martensitic structure occurs, to Mf+200°C. It is a strong material with a yield strength of 8 even in a solution treatment machine before aging.
It is characterized by forming maraging steel having a weight of 0 kg/- or more.

The present invention will be specifically described below based on embodiments shown in the drawings.

That is, FIG. 1 shows the results of measuring the 0.2% proof stress at a constant temperature during cooling after solution treatment at 830°C.

Sample components are CO, 011, Ni18.75゜Mo4.6
7, Co9.08. AtO, 07, Ti0.58 M
Point 7 is at 110°C.

As shown in this figure, from the tensile test results, 1
At temperatures above 50℃, the yield strength σ0.2 is approximately 20 to 97m1
t, it decreases to 1/4 or less compared to 80 kg/- at room temperature.

When molding is performed at such a temperature, even if there is anisotropy in Young's modulus, the amount of springback is small and the amount of deformation associated with it is also reduced.

However, as the molding temperature increases, thermal strain increases during the cooling process after molding, which increases deformation.

Of course, if the mold is also cooled all at once, deformation can be prevented no matter how high the molding temperature is, but this is not practical.

The upper limit temperature at which the released molded product is not affected by thermal strain during cooling is Mf + 200°C, and even better is M7.
It was experimentally confirmed that the temperature was +140°C.

Plate thickness Q, 5 made of tUtc18Ni maraging steel
The shapes shown in Figure 2 A and B are made from a 1m disk at room temperature and 225cm.
The molded product 1 was press-formed at 30°C and set on the block 3 as shown in Fig. 4A, and while rotating, the height from the surface plate 4 at the position indicated by arrow A was measured, and its maximum height was determined. The minimum difference is shown in Table 1 below as the amount of deformation.

Also, a plate made of 18Ni maraging steel has a thickness of 1. The shape shown in Fig. 3A and H is press-molded from a circular plate of On at room temperature and 225°C, and this molded product 2 is set on the block 3 as shown in Fig. 4B, and while being rotated, The heights from the surface plate 4 at the positions indicated by , C were measured, and the difference between the maximum and minimum values is shown in Table 1 below as the amount of deformation.

According to this result, the amount of deformation such as warping and twisting during press molding at 225° C. can be significantly reduced to 1/13 to 1/2 compared to room temperature molding.

Therefore, post-process handling and deformation correction can be easily performed.

As explained above, the present invention performs heating solution treatment,
This method then cools down to the molding temperature and performs warm press forming, so the amount of deformation can be significantly smaller than at room temperature, making it easier to handle and correct deformation in subsequent processes. play.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the relationship between yield strength at a constant temperature during cooling after solution treatment at 830°C, Figure 2 A is a plan view showing an example of the shape of the molded product, and Figure 2 B is a central sectional view of FIG. 2A, FIG. 3A is a plan view showing another example of the shape of the molded product, FIG. 3B is a sectional view taken in the direction of arrow E of FIG.
Figure A is a diagram showing the deformation measurement position of the molded product shown in Figures 2A and B, and Figure 4B is a diagram showing the deformation measurement position of the molded product shown in Figures 3A and H. σ0.2...Proof strength, 1,2... Molded product.

Claims (1)

[Claims] 1 After heating the maraging steel plate for solution treatment,
A method for press forming a maraging steel sheet, which comprises performing press forming such as bending, drawing, stretching, and burling within a temperature range of 110°C to 310°C during cooling.