JPS625984B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to the creation of a high manganese non-magnetic steel with a significantly high resistivity, and is capable of significantly reducing energy loss and disturbance of the magnetic field due to the generation of eddy currents, which are problems when using non-magnetic steel in a magnetic field. The aim is to provide a non-magnetic steel that can be used. In recent years, high manganese austenitic steel has been applied as an inexpensive non-magnetic steel to structural members such as magnetic levitation linear motor cars and plasma generators for nuclear fusion reactors. In other words, the purpose of using non-magnetic steel in such a strong magnetic field is to prevent disturbance of magnetic flux distribution and loss of magnetic energy when using ferromagnetic material (ordinary steel), and it is not suitable for such purposes. The use of aluminum alloys and copper alloys, which are magnetic metal materials, is also suitable, but another important problem that disturbs the magnetic flux distribution is the disturbance of the magnetic flux distribution due to the generation of eddy currents that occur when the magnetic flux passes through the metal. There are also eddy current losses. Aluminum alloys and copper alloys with low resistivity are not suitable for preventing this eddy current, and high-manganese austenitic steel has a significantly higher resistivity, which is 20 to 30 times higher than that of aluminum alloys and copper alloys. This means that the eddy current can be reduced to 1/20 to 1/30. The magnitude of this eddy current is inversely proportional to the magnitude of electrical resistance, and a non-magnetic steel with high resistivity and excellent non-magnetism is desired.
I can hardly find anything suitable for such a purpose. The present invention was devised after repeated studies in view of the above-mentioned circumstances, and it takes a high-manganese non-magnetic steel that has an extremely high specific resistance and extremely stable non-magnetic properties, and improves other properties by adjusting the chemical composition. It is designed to provide economic benefits without causing significant damage. Furthermore, it is generally known that the specific resistance P is the reciprocal of the electrical conductivity, and when the length is l and the cross-sectional area is S, the electrical resistance R is expressed as R=P×l/S. It is exactly as it is written. To further explain the present invention as described above, the basic characteristics of the present invention are that C: 0.01 to
Contains 1.5%, Si: 3.0~10%, Mn: 20~30%,
The remainder consists of Fl and unavoidable impurities, and if necessary, Cr, Ni, Cu, Co, Mo and 1% each of Cr, Ni, Cu, Co, Mo and 1
% or less of one or more elements of Al, Nb, Ti, and V, and such non-magnetism as used in the present invention means that it exhibits a value of magnetic permeability of 1.02 or less. be. Regarding the present invention as described above, the reason for limiting the chemical components is as follows. If C is less than 0.01%, it is difficult to obtain mechanical strength, and furthermore, reducing the C content to less than 0.01% requires special refining, which impairs economic efficiency. On the other hand, if the C content exceeds 1.5%, the precipitation of carbides will significantly impair non-magnetism, as well as the weldability and machinability, making it impossible to use as a structural material. Mn is a basic component constituting high manganese nonmagnetic steel along with C, and is essential as an austenite stabilizing element. If it is less than 20%, it is difficult to obtain a stable austenite structure and nonmagnetism is significantly impaired. Also, if the content exceeds 30%, the cost will increase and the difficulty in manufacturing will also increase.
The upper limit was set at 30%. Si is an important element that increases specific resistance in the present invention, and the effect of increasing this specific resistance is insufficient if it is less than 3%, while Si content exceeding 10% will affect the stability of austenite. loss,
In addition, it will significantly impair weldability and machinability, so 3 to 10%
The range of Next, Cr, Ni, Cu, Co, Cu, Mo, Al, Nb,
Ti and V can be added to high manganese austenitic steel to improve mechanical properties such as high strength and toughness, and to supplement non-magnetic stability. Regarding Mo, the effect is saturated even if it is contained in excess of 5%, and
For Al, Nb, Ti, and V, the effect is saturated even if the content exceeds 1%, and in any case, adding more than this will not produce an effect commensurate with the increased amount.
Since it only impairs economic efficiency and also has an adverse effect on hot workability, the respective specified amounts were set as upper limits. However, it is generally known that the resistivity of austenitic steel increases with the addition of any alloying element, but the extent of this increase varies depending on the type of alloying element. That is, Figure 1 shows the increase in resistivity when various alloying elements are added to high manganese austenitic steel with 0.25%C-25%Mn as a pace component. Even if alloying elements such as Mo and Cr are added up to about 5%, the increase in resistivity remains below 10μΩcm. However, Si significantly increases the resistivity and has an effect 3 to 7 times greater than these other alloying elements, but when Si is added at less than 3%, it is within the range that can be achieved with other alloying elements and does not show a significant effect. . Finally, regarding N, if it is less than 0.005%, the stabilization of austenite is likely to be lost, and the manufacturing itself is difficult, impairing economic efficiency, while if it is more than 0.1%, it impairs the hot workability of the steel. 0.005~0.1
It is preferable to set it as the range of %. To explain a specific manufacturing example of the product according to the present invention, Table 1 below shows the results of measuring the specific resistance value and magnetic permeability at room temperature of various high manganese steels with different composition systems. Specific resistance was measured by the four-terminal method, and magnetic permeability was measured by the solenoid method.
This shows the value in a 100Ol magnetic field. Note that the N content of the sample steels was all within the range of 0.01 to 0.05%. That is, in Table 1 above, steels C, D, H, I, and L have the chemical composition according to the present invention, but all exhibit a specific resistance exceeding 100 μΩcm and a magnetic permeability of 1.002 or less. It can be seen that it exhibits extremely good nonmagnetism. That is, this specific resistance value is significantly larger than that of aluminum: 2.69 μΩcm, copper: 1.67 μΩcm, and carbon steel: 10 to 20 μΩcm, and is slightly less than twice that of ordinary high manganese austenitic steel. On the other hand, among the comparative steels, Steel E is
Although more than 10% Si is added, although the specific resistance shows a large value, the stability of austenite is impaired.

[Table] The magnetic permeability shows large values. Also, steel G is
When the Mn content is less than 10%, stable austenite cannot be obtained and the steel does not function as a non-magnetic steel. Also steel A, B, F, J and K
are all steel types with a Si content of less than 2%, but even if various alloying elements are added, the specific resistance value remains the same.
Stays below 80μΩcm. As described above, the present invention is basically achieved by adding 3% or more of Si and 20 to 30% of Mn in the chemical component range that stabilizes austenite, and the presence of other alloying elements The effect is not lost even at the bottom. Moreover, the effects of the present invention will not be impaired even if Ca is added in an amount of 0.08% or less, S is added in an amount of 0.1% or less, or a combination of both is added for the purpose of improving machinability. Further, the effects of the present invention are not affected by the shape of the product, and can be applied to rolled steel products such as steel plates, steel pipes, and long steel products, as well as cast and forged steel products. According to the present invention as described above, the energy loss and disturbance of the magnetic field due to the generation of eddy currents are significantly reduced, and high manganese nonmagnetic steel with high resistivity can be economically provided, which is suitable for industrial use. This is a highly effective invention.

[Brief explanation of the drawing]

The drawings show the technical content of the present invention, and
The figure is a chart showing the influence of each alloying element on resistivity.

Claims (1)

[Claims] 1 C: 0.01~1.5%, Si: 3.0~10%, Mn: 20~
High manganese nonmagnetic steel with extremely high specific resistance, characterized by containing 30% of manganese and the remainder consisting of iron and unavoidable impurities. 2 C: 0.01~1.5%, Si: 3.0~10%, Mn: 20~
Contains 30% and further contains Cr: less than 5%, Ni: 5% or less, Cu: 5% or less, Co: 5% or less, Al: 1% or less, Nb: 1% or less, Ti: 1% or less, V : A high manganese nonmagnetic steel with an extremely high resistivity, characterized by containing 1% or less of any one or two or more, with the remainder consisting of iron and unavoidable impurities.