JP6460475B2 - Solid solution strengthened austenitic steel sheet - Google Patents

Description

  The present invention relates to a solid solution strengthened austenitic steel sheet.

Conventionally, in the electronics field, an Fe-36 mass% Ni alloy has been used as an alloy that provides low thermal expansion characteristics. This alloy is used for, for example, a metal mask by utilizing the characteristics.
Furthermore, for the purpose of increasing the tension of the Fe-36 mass% Ni alloy, Japanese Patent Laid-Open No. 2000-355739 (Patent Document 1) discloses one or two of Nb, Ta, Ti, Al, Mo, and W. There is also a proposal of an alloy containing 0.1 to 5.0% of seeds or more in total. This proposal is excellent in that a higher tension than that of the Fe-36 mass% Ni alloy can be obtained while maintaining low thermal expansion characteristics.

JP 2000-355739 A

Although the alloy disclosed in Patent Document 1 described above is advantageous in terms of achieving both low thermal expansion characteristics and high tension characteristics, in recent years, as the thickness of the base material has progressed in the electronics field where weight reduction is ongoing, There was a problem of shortage. Insufficient strength due to thinning of the base material becomes a serious problem when used as an electronic member requiring high accuracy.
An object of the present invention is to provide a solid solution strengthened austenitic steel sheet that is excellent in low thermal expansion characteristics with increased tension, that is, strength, in order to meet the demand for thinner substrates.

The present inventor examined the problem of strength reduction accompanying the thinning of the base material used for the electronic member, added an alloy element in an appropriate range to austenitic steel, and used the solid solution strengthening mechanism to improve the strength characteristics. The inventors have found that it can be greatly improved and have reached the present invention.
That is, the present invention is a solid solution strengthened austenitic steel sheet for performing an etching process, and in mass% , Mo is more than 5% and 10% or less , 34 to 38% Ni, 1% or less Mn, remainder Ri such Fe and impurities, is not less 300μm or less in thickness, is solid solution strengthened austenitic steel sheet Ru der least 850MPa both tensile strength and 0.2% proof stress.

  Since the solid solution strengthened austenitic steel sheet according to the present invention is excellent in strength characteristics, it has an effect of suppressing a decrease in strength due to thinning. Therefore, the use of this makes it possible to reduce the weight of the electronic member and lead to an improvement in product dimensional accuracy by reducing the handling property during manufacturing and the amount of deformation.

As described above, an important feature of the present invention is that the amount of the solid solution strengthening element to be added is greatly increased as compared with the conventionally used austenitic steels such as Fe-Ni alloys.
In the solid solution strengthened austenitic steel sheet of the present invention, the reason why the range of each additive element and its content is specified is as follows. Unless otherwise specified, the mass% is indicated.
<Ni: 34-38%>
The reason why Ni is 34 to 38% is that Ni stabilizes the austenite structure to room temperature and obtains low thermal expansion characteristics. If Ni exceeds 38%, the coefficient of thermal expansion increases and the material cost increases significantly. On the other hand, when Ni is less than 34%, the austenite phase cannot be stably present at room temperature and the thermal expansion coefficient is increased. Therefore, Ni was made into the range of 34 to 38%. In order to exhibit the above-described effect of Ni more reliably, the upper limit of Ni is preferably 37%, and the lower limit of Ni is preferably 35%.
<Mn: 1% or less>
Mn improves the workability such as hot working required in the manufacturing process of the thin plate, while causing an increase in the coefficient of thermal expansion, so the upper limit is 1%. In order to more reliably obtain the effect of improving the hot workability of Mn, it is preferable to set the lower limit of Mn to 0.5%.

<M o: 10% or more under more than 5%>
Mo is an element having a high solid solution strengthening ability because it dissolves in substitutional form in austenite and has a large dimensional difference from the Fe atom radius. Furthermore, since the atomic weight is large and the diffusion coefficient in Fe is small, phase stability can be maintained over a long period of time, and strength and phase stability can be obtained.
If M o exceeds 10 %, M o cannot be present stably in austenite and precipitates are formed. Therefore, not only high strength cannot be obtained, but also the thermal expansion coefficient increases. Thus the upper limit of Mo is 10% or less. On the other hand, when the Mo is 5% or less, it is impossible to compensate for the strength reduction accompanying the thinning of the base material. For this reason, it was 10% or less than 5% of M o. A preferred range of Mo 6% or more and 10% or less.
<Remainder>
The balance other than the additive elements described above is substantially Fe. However, impurities that are inevitably mixed in production are included. Although it is preferable that the impurity content is small, it may be within the following range.
P ≦ 0.01%, S ≦ 0.01%, Co ≦ 0.6%, Cu ≦ 0.2%

Aforementioned alloy metal structure exhibits an austenitic phase, by M o is a solid solution in the matrix (base), in which excellent strength is obtained. In order to fully exhibit this effect, it is preferable that the thickness of the solid solution strengthened austenitic steel sheet be 300 μm or less. If it is 300 micrometers or less in thickness, it will become suitable also for the use which etches, for example. The thinner the plate is, the more effective the strength of the present invention is. Therefore, the thickness is preferably 200 μm or less. In addition, the thin plate said by this invention means the thing from which thickness became about 500 micrometers or less, and cold rolling is preferable for adjustment to this thickness.

The following examples further illustrate the present invention.
A 10 kg steel ingot is produced by vacuum melting, hot rolled to produce a bar with a cross section of 30 mm × 30 mm, a plate having a thickness of 2 mm, a width of 25 mm, and a length of 100 mm is cut out by electric discharge machining, Rolling and annealing at 950 ° C. × 15 min were repeated to produce a solid solution strengthened austenitic steel sheet having a thickness of 0.2 mm. The chemical composition is shown in Table 1.

  Each test piece was sampled from a solid solution strengthened austenitic steel sheet having a thickness of 0.2 mm. In the tensile test, the above-described rolled material was subjected to strain relief annealing at 500 ° C. for 15 min to produce a tensile test piece having a parallel part length of 20 mm and a width of 25 mm, and 0.2% under the conditions of a tensile speed of 2 mm / min (constant until breakage). Yield strength and tensile strength were measured. The coefficient of thermal expansion was obtained by cutting a test piece having a width of 4 mm and a length of 19.5 mm from the above-described rolled material, and measuring a coefficient of thermal expansion between 30 and 100 ° C. under a temperature rising rate of 5 ° C./min. The results are also shown in Table 2.

No. of the present invention to which Mo was added. No. 1 austenitic steel sheet had a 0.2% proof stress and a tensile strength of 850 MPa or more. Moreover, No. of the reference example which added W. In 2. A tensile strength 2% yield strength are both above 700MPa was obtained in Reference Example No. In Comparative Example No. 3 as well. Higher 0.2% yield strength and tensile strength than 11 austenitic steels are obtained.
Moreover, it turns out that an intensity | strength level increases with the increase in the addition amount of Mo or W. Although the thermal expansion coefficient also increases with the addition amount of Mo and W, the austenitic steel of the present invention has a thermal expansion coefficient of 10 × 10 ⁻⁶ or less and has a lower thermal expansion characteristic than general steel. ing.
From the above, the present invention is excellent in high strength characteristics and low thermal expansion characteristics, and therefore can be applied to applications of electronic members that require weight reduction, handling properties, and dimensional accuracy of products.

Claims (1)

A solid solution strengthened austenitic steel sheet for performing an etching process, and in mass%, more than 5% and 10% or less Mo , 34 to 38% Ni, 1% or less Mn, remaining Fe and impurities Do Ri, is not less 300μm or less in thickness, solid solution strengthened austenitic steel sheet, characterized in der Rukoto both 850MPa or higher tensile strength and 0.2% proof stress.