JPS5842761A - Manufacture of titanium plate - Google Patents

Abstract

PURPOSE:To manufacture a Ti plate with high bendability and high surface accuracy by regulating the average grain size of a blank Ti plate and the diameter of a cold rolling roll so as to provide a specified relation, descaling the plate with a fine shot blasting material, and cold rolling it. CONSTITUTION:Assuming the average grain size of a blank Ti plate to be Xmum and the diameter of a cold rolling roll to be Ymm., they are regulated so that the relation between them satisfies equationI. By regulating the grain size X when the roll diameter Y is fixed or the roll diameter Y when the grain size X is fixed, the maximum oil pit depth can be restricted to <= about 10mum. After regulating the relation between the grain size X and the roll diameter Y as mentioned above, the plate is descaled with a fine shot blasting material having less than the volume corresponding to 0.4mm.phi spheres, and it is cold rolled to manufacture a cold rolled Ti plate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a titanium plate with good bending workability and surface precision.

Titanium is a metal that easily seizes, and it easily seizes under high pressure and high rolling speed, and the above properties are detrimental in the case of cold rolling. Seizure during cold rolling of titanium sheets is characterized by the fact that titanium firmly adheres to the roll surface during the rolling process.

Once seizure occurs, it becomes more likely to occur during subsequent rolling. Once cracking occurs, the original oscillation coefficient increases rapidly and the rolling load increases, making it extremely difficult to ensure stable rolling and a good sheet shape. Particularly in large-diameter roll rolling, where high-speed rolling is possible and it is easy to obtain a good plate shape, sufficient moisture f! There is a growing need for rolling under the R condition, and in response to this requirement, we have developed the following improvement measures and have already filed a patent application.

11) A method of using a highly saponified oil having a saponification value of 170 or more as a rolling lubricant (Japanese Patent Application Laid-open No. 145849/1984).

(2) A method of forming an oxide film on the surface of a cold-rolled blank sheet and cold rolling it (@Kokai No. 54-888fi8).

By applying the above methods (1) and 12) alone or in combination, seizure during cold rolling can be prevented. However, according to separate research conducted by the inventor, even when seizure is prevented as much as possible, depending on the relationship between the crystal grain size of the titanium soundboard and the rolling row A/diameter, the entire surface of the cold-rolled plate may be damaged. It was found that countless oil bits were generated and the surface area was significantly reduced.

Therefore, as a result of pursuing the cause of oil bit generation and researching its improvement measures, we found that (A) the cause of oil bit generation is a so-called fluid #cleaning situation where a large amount of dripping oil is introduced during the low bite. It is thought that there is one color) that #
** is the average crystal grain size of the titanium base plate in X (μm)
, when the diameter of the cold rolling roll is Y (tm), 1
It is effective to perform cold rolling under conditions where both satisfy the following relationship! Recognizing this, we filed a patent application (Japanese Patent Application No. Sho R1S-69174).

That is, as confirmed by the present inventors in previous research,
Oil pit depth d: μm) and crystal grain size of the base plate (x:
μm) and the cold rolling roll diameter (Y: fin) are d, , 0.287-X'-"'0-"', (
There is a correlation between n) and Y, and once the maximum allowable oil pit depth d) for vI is determined, the average grain size CX of the titanium blank to be used and the cold rolling row A/diameter are determined. It can be organized into the relationship (Y). On the other hand, in this industry, “depth 10
Since there is a demand from the customer side that there should be no surface defects larger than μm, the maximum allowable oil pit depth (cl) is set at 10 μm, and by substituting this into the above equation (IT), the following ("III ) formula is established.

10 Σ 0.287 -IO・”' -Y O”
7-(III) When this is transformed into a hairstyle, the above formula CI) is derived.

That is, ■ When the cold rolling roll A/diameter (Y) to be used is determined, adjust the average grain size (X) of the titanium blank so as to satisfy [Equation 13], and ■ Adjust the average grain size ( When cold rolling a titanium blank having a fixed value of X), the maximum oil pit depth can be suppressed to 1075 m or less [by adjusting the roll diameter (Y) so as to satisfy Equation 13].

But then I! As a result of our research, we found that even when cold rolling was performed using the above technology.

Surface defects such as deep cracks may occur.

The present invention also establishes a new method for the above-mentioned 1 MA (this was completed as a result of intensive research).

Its structure consists of preparing various titanium blanks that meet the conditions of the above CI) formula, descaling them using a rutted-axis or lot-presto material with a volume equivalent to a 0.4 wφ sphere, and then cold-rolling them. The gist is there.

As mentioned above, even when cold rolling is carried out under conditions that satisfy the requirements of formula 13, surface defects in the form of deep cracks may occur in the rolled sheet (reference photo 1). When a conventional titanium plate cold rolling method (a rolling method with poor lubrication and a risk of seizure) is used, surface defects due to seizure occur, but deep crack-like surface defects as described above occur. The MWg was that there was no (reference photo 2). From this.

In order to reduce deep crack surface defects to <1k, consideration from another angle is considered necessary.

When we investigated the cause of the above-mentioned crack-like defects, we found that the cause was a work-hardened layer formed on the surface of the titanium blank during VIM-F plasticization before cold rolling. jl! ] Since the surface of a hot-rolled titanium sheet is covered with finely dense and strong tk# scale, which is unique to titanium, the scale is usually destroyed by the VMI-F plasting method prior to cold rolling, and then the surface layer o *g diffusion layer (approximately 80~6G
.

In the above-mentioned shit-plast process, a work-hardened layer is formed on the surface of the titanium blank due to impact energy, but the thickness of this work-hardened layer (the thickness after pickling) is different from the crack-like defect. It turned out that it was related to the police. In other words, Figure @1 shows the thickness and hardness of the work-hardened layer Hv, 1
00g) is a graph showing the influence that it has on the crack-like defects. The titanium blank and cold rolling conditions were as follows.

Titanium blank; pure titanium hot-rolled plate (thickness 8 fins, 1gl fine M crystal grain material, with work-hardened layer by V*tplast and removed by pickling) Cold rolling conditions: beef tallow rolling Oil, roll diameter 150■φ,
The scale was completely removed by applying a rolling speed of 48 m/min and a total rolling reduction of 50 m/min.

Further, the cold rolling conditions shown in Table 8 are good lubrication conditions that do not cause seizure.

FIG. 2 shows the relationship between the work-hardened thickness of the surface of each titanium plate obtained above and the dimensions of the V-yoat material.

As is clear from Figure 2, the length of the work-hardened layer is SIN
There is a tendency that the smaller the dimension tIK of the cut material and the smaller the crystal grain size, the thinner the material becomes. [Same conventional] The VMt material used for the VM footlast of titanium plate is approximately 0.5
It is a steel ball with 1 layer of s1φ or a cut wire with a length of about 1 to 2 cm, and the machining depth is large in this type of material.

Fine 1kg! By using cut material, the machining depth can be significantly reduced.

In addition, No. 8 and 4 @ show the relationship between work-hardened layer thickness and crack-like defects for fine-grained materials and coarse-grained materials. The amounts in 11.1 have the following meanings.

12 There was a crack-like defect at the rolling reduction rate of bO.] 0: No crack-like defects at rolling reduction of 50 inches Rolling: There are crack-like defects at a reduction rate of 75.) B; No crack-like defects at 475 degrees of rolling. From Figure 8.4, it can be considered as follows.

What is the maximum defect depth when there is no work hardening layer?

Although it is determined by the crystal grain size of the titanium blank and the diameter of the rolling roll, the presence of a work-hardened layer affects the grain size, and a similar tendency is observed. The maximum defect depth decreases as the work-hardened layer becomes thicker, up to 160 μm. This is because the defects are destroyed by collisions between crystal grains on the surface of the titanium plate or the VB material, and the appearance is that of the upper crystal grains. This is thought to be due to the diameter being fine [71 However, when the depth of the work-hardened layer is 150 μm, crack-like defects are observed), and after that, as the layer thickness increases, the crack-like defects decrease to 1. At the same time, the I/c# large defect depth also increases rapidly.

In other words, in order to prevent crack-like defects on the surface of a cold-rolled plate, the thickness of the work-hardened layer must be 1! It is effective to control the shot blasting conditions so that it is sOμm or less, and in consideration of the relationship with the maximum defect depth, a range of 50 to 160μm is optimal. The most effective way to reduce the maximum hardened layer thickness is to reduce the size of the shot material used in the shotplast process, as explained in Figure 2. Considering the thickness of the work-hardened layer (80~FhO#m), it is assumed that
By using short material.

The thickness of the work-hardened layer after pickling can be 150 μm or less.

By the way, reference photo 6 shows an example of the surface condition after rolling when the dimensions of the vm-tplast material are changed.The crack-like defects of the shot material, which is one dimension smaller, are V! It is extremely small compared to those using wood.

Figure 6 is a graph showing the relationship between the work-hardened layer thickness and bending performance by t/Htplast (plate thickness Ram, using a pure titanium plate such as a fine-grained material).1. The m1 hardened layer thickness is also closely related to bending performance. This figure] is the standard for the bending radius of pure titanium 8W plate, 2, OT (
In order to satisfy the requirement (twice the plate thickness), the work hardening layer thickness must be 18
Although it is necessary to reduce the thickness to 0 μm or less, this requirement is certainly met by the descaling treatment using a V-yield material having a diameter of 0.4 μm or less as defined in the present invention.

As described above, one of the features of the present invention is that the thickness of the work-hardened layer is set to 150 μm or less by using fine particles with a volume equal to or less than a 04txφ sphere as the vMt material, and these effects are It is effective regardless of the material of the V-lot material, but considering that work hardening is caused by the impact energy of the shot material, it is recommended to use a relatively soft and lightweight sheet material such as M-fused alumina powder. It is also highly preferred to use

The present invention is roughly constructed as described above, and the relationship between the average crystal grain size X (#m) of the titanium blank and the diameter Y (fin) of the cold rolling roll satisfies the following formula % formula % In addition to the configuration of the prior invention in which the titanium blank is adjusted and cold rolled, the descaling treatment of the titanium blank before cold opening is adjusted to 0.
4■ Fine V with a volume less than the volume equivalent to a φ sphere! By using an IT-plast material and adding the requirement of suppressing the thickness of the work-hardened layer to 150 μm or less, it became possible to produce a cold-rolled titanium sheet with excellent surface precision and workability.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the distance from the surface and strength after descaling treatment, Figure 2 is a graph showing the relationship between the dimensions of the VM beam material and the thickness of the work-hardened layer, and Figure 8.4 is the graph showing the relationship between the distance from the surface and the strength after descaling. A graph showing the relationship between the hardened layer thickness and the maximum defect depth, and FIG. 5 is a graph showing the relationship between the work hardened layer thickness and the bending radius. Work hardened layer thickness μm) Work hardened layer thickness μm) Work hardened layer thickness μ'm)

Claims (1)

[Claims] (1) When the average crystal grain size of the titanium soundboard is X (1 m) and the diameter of the cold rolling roll is Y (ms), the relationship between the two should be adjusted so that it satisfies the following formula %, and 0 .4■ A method for producing a titanium plate, which comprises performing cold rolling after descaling using a thin VB-plated plastic material having a volume equal to or less than that of a φ sphere.