JPH0313889A - Bimetal with excellent clad adhesion - Google Patents

Abstract

PURPOSE:To improve the close adhesiveness of a low thermal expansion material or an intermediate material by constituting a high thermal expansion material of an Fe-Ni-Cr alloy containing boron and nitrogen. CONSTITUTION:A high thermal expansion member is constituted of an Fe-Ni-Cr alloy having a composition containing C 0.2% or less, Si 1.5% or less, Mn 1.0% or less, A 0.03% or less, Ni 15 - 30%, Cr 1 - 15%, B 0.001 - 0.01% and N 0.001 - 0.01% and consisting of the remainder of Fe and inevitable impurities. At the time of annealing after cold rolling in a process preparing the high thermal expansion member from said alloy, B and N contained as alloying components are diffused and migrated to the surface part of the member to become a state present in a bonded BN form and the surface part becomes hard to be reduced in plastic deformation capacity and therefore, an active new surface becomes easy to form at the time of clad rolling and close adhesiveness is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Applications ff] The present invention relates to a bimetal that has extremely high adhesion of a high thermal expansion member to a low thermal expansion member or an intermediate material.

[Conventional technology]

Generally, bimetals are produced by forging an ingot, hot rolling, cold rolling, and then, for example, in a hydrogen atmosphere at a temperature of 7.
A high thermal expansion member and a low thermal expansion member of a predetermined thickness, each prepared by annealing at 50°C for 1 hour, are stacked on top of each other via an intermediate mill as necessary, and then cold rolled. It is manufactured by cladding. In this case, as the high thermal expansion member, for example, JP-A-58-20108
As described in Publication No. 8, C: 0.2% or less, Si: 1.5% or less.

Mll, 2.0% or less, Nl: 15-3D%,
Cr: 1 to 15%, N: 0.08% or less.

Fe-N containing a and the remainder consisting of Fe and unavoidable impurities (the above weight %, below % shows weight %)
i-Cr alloy, and as a low thermal expansion member, Fe
It is also well known that -35 to 37% Ni-based amber alloys, as well as Cu and Cu alloys, Ni and Ni alloys, etc., are used as intermediate materials.

[Problem to be solved by the invention]

On the other hand, in recent years, with the improvement in performance and weight reduction of various types of electrical equipment and mechanical devices, the conditions for using bimetals used in these devices have become even more severe.Particularly in the case of bimetals, these harsh conditions In order to enable use in accordance with This is undesirable from both equipment and operational standpoints.

[Means to solve the problem]

Therefore, from the above-mentioned viewpoint, the present inventors have developed a bimetal with excellent adhesion to a low thermal expansion member or an intermediate material for a high thermal expansion member (as a result of research,
Especially for bimetal high thermal expansion members, C: 0.2% or less, Si: 1.5% or less Mn: 1
．． 0% or less, AΩ: 0.03% or less.

N1: 15-30%, Cr: 1-15%.

B: 0.001 to 0. O1%, N:0
．． 001 to 0.01%.

When an Fc-Nl-Cr alloy is used, the balance being Fc and unavoidable impurities, B is added as an alloy component during annealing after cold rolling in the manufacturing process of high thermal expansion parts. ,l! :N diffuses and moves to the surface of the member and exists in the form of bonded BH, so the surface has a higher hardness than the center of the member, and as a result, the plastic deformability becomes smaller. During cladding by cold rolling with a low thermal expansion member in the next step, a new active surface is likely to be generated on the surface of the high thermal expansion member even at a low rolling rate. They found that the adhesion was improved.

Therefore, the present invention has been made based on the above findings, and provides a bimetal formed by cladding a high thermal expansion member and a low thermal expansion member directly or via an intermediate material, in which the high thermal expansion member is C:0. 2% or less Si: 1.5% or less.

Mn: 1.0% or less, AΩ: 0.03% or less.

Ni: 15-30%, Cr: 1-15%.

B: (from 1,001 to 0.019, N:
0.001-0.01%.

This is a bimetal with excellent cladding adhesion, which is composed of a Fe--Ni--Cr alloy having a composition of H and the remainder being Fe and unavoidable impurities.

Next, the reason why the component composition of the high thermal expansion member in the bimetal of the present invention is determined as described above will be explained.

(a) C The C component has the effect of suppressing deformation-induced martensitic transformation, which causes a decrease in the coefficient of thermal expansion, but when its content is 0
．． If it exceeds 2%, it will tend to form carbides, reducing corrosion resistance and moldability.
Its content was set at 0.2% or less.

(b) Si The Si component also has the effect of inhibiting the occurrence of deformation-induced martensitic transformation, but when its content exceeds 1.5%, hot workability and tightness deteriorate. Therefore, its content was set at 1.5% or less.

(e) Mn Like the C and Si components, the Mn component also has the effect of making deformation-induced martensitic transformation difficult to occur and preventing a decrease in the coefficient of thermal expansion due to the occurrence of this transformation.
Even if it exceeds 0%, the coefficient of thermal expansion tends to decrease, so the content was set at 1.0% or less.

(d) The AN l component has a strong deoxidizing effect, but if its content is 0.
If the content exceeds 0.03%, the hot workability and the cleanliness of the alloy will decrease.
It was set at 0.3% or less.

(c) Ni and Cr Ni and Cr components are essential components to ensure a pseudo coefficient of thermal expansion in order to fully exhibit the function of a high thermal expansion member. Therefore, the contents of Nl and Cr are respectively If Ni: less than 15% and Cr: less than 1%, the desired high coefficient of thermal expansion cannot be obtained, and on the other hand, even if the content exceeds Ni + 30% and Cr: 15%, a decrease in the coefficient of thermal expansion is unavoidable. , its content is N
I: 15-30%, C: 1-15%.

('') B and N The B and N components combine to form BN as described above, and this is diffused in large quantities on the surface of the member, increasing the hardness and thereby increasing the plastic deformability of the surface of the member. From lowering
At the time of cladding in the next process, a new active surface is more likely to appear, and high adhesion strength can be obtained even at a low rolling rate. Less than and N: 0.001%
If the content of B is less than 0.01%, the BN ratio on the surface of the part is too small and the desired effect cannot be obtained. On the other hand, if the content of B exceeds 0.01%, hot workability decreases. Not only does the coefficient of thermal expansion become smaller, but also the content of N decreases to 0.019fi.
If it exceeds B, the amount of nitride formed will be large (and the hot workability will rapidly deteriorate), so the content should be adjusted to B: 0.001 to 0.01%.

N: determined to be 0.001 to 0.01%.

〔Example〕

Next, the bimetal of the present invention will be specifically explained using examples.

Fc-Nl-Cr alloys having the compositions shown in Table 1 are used for forming high thermal expansion members.
fi: Prepared in a 10 kg atmospheric melting furnace, cast into an ingot under normal conditions, hot forged, hot rolled into a hot rolled plate with a thickness of 5 mm, and then cold rolled. After that, it was made into a cold-rolled sheet with a thickness of 0.5 m +++, and then annealed in a hydrogen atmosphere at a temperature of 870°C for 2 minutes, while the composition was changed to Fe -36.1%. N1
A cold-rolled plate for forming a low-thermal-expansion member was prepared under the same conditions except that the two cold-rolled plates were stacked together, and a cladding was formed by cold rolling at a rolling rate of 50% using a four-high rolling mill. As a result, bimetals 1 to 12 of the present invention and a conventional bimetal containing no B having a thickness of 0.5nos were manufactured.

Next, from the various bimetals obtained as a result, 15
．． Cut out a test piece with planar dimensions of 0mm x 25mm, peel off one half of the test piece in the length direction,
The peeled portions were each bent at 90° to form a single-shaped test piece, which was used to perform a tensile test, and the adhesion strength was determined as D1. These results are shown in Table 1.

Furthermore, when the distribution of B and N on the surface of the cold-rolled sheet for forming a high thermal expansion member before cold cladding of the bimetal 2 of the present invention was observed by Auger analysis, the results shown in FIG. 1 were obtained.

Furthermore, in the stacked body of the bimetal 2 of the present invention and the conventional bimetal, a cold-rolled plate for forming a high thermal expansion member and a cold-rolled plate for forming a low thermal expansion member before cold cladding, 30 to 6
When cladding was applied by cold rolling at a rolling rate of 3% and the adhesion strength was determined by l1l-1, the results shown in FIG. 2 were obtained.

〔Effect of the invention〕

As shown in FIG. 1, the bimetals 1 to 12 of the present invention all have a high BN'a degree on the surface of the cold-rolled sheet for forming a high thermal expansion member before cold cladding, and are hardened, so they are not activated when cladding. As shown in Table 1, the new surface easily appears, and compared to conventional bimetals that do not contain B and therefore do not form BN, they exhibit strong adhesion strength as shown in Table 1, and as shown in Figure 2. As shown, even if the rolling reduction during cold cladding is lower than that of conventional bimetals, it shows the same density 6 strength.

As mentioned above, the bimetal of the present invention has high adhesion strength of the low thermal expansion member or intermediate material to the high thermal expansion member, which not only makes it possible to lower the rolling rate during cold 1 ul cladding, but also makes it possible to It has industrially useful properties such as being able to be put to practical use under certain conditions.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the concentration distribution of B and N in the cross section of the back side of a cold-rolled plate for forming a high thermal expansion member of the bimetal 2 of the present invention, and FIG. 2 is a diagram showing the cold cladding rolling rate of the bimetal 2 of the present invention and the conventional bimetal. It is a figure showing the relationship with dense awn strength.

Claims (1)

[Claims] (1) In a bimetal formed by cladding a high thermal expansion member and a low thermal expansion member directly or via an intermediate material, the high thermal expansion member is, in weight%, C: 0.2% or less, Si: 1.5% or less, Mn: 1.0% or less, Al: 0.03% or less, Ni: 1
5-30%, Cr: 1-15%, B: 0.001-0.
01%, N: 0.001 to 0.01%, and the remainder is Fc and unavoidable impurities.
A bimetal with excellent clad adhesion characterized by being composed of a Cr-based alloy.