JPS5983743A - High manganese steel excellent in machinability - Google Patents

Abstract

PURPOSE:To provide non-magnetic high Mn-steel enhanced in machinability such as lathe cutting property or drillability, by adding proper amounts of Bi and Ni, Cr, Al, Nb or V to high Mn-steel having a specific composition. CONSTITUTION:High Mn-steel comprises 0.01-1.2% C, 0.2-3.0% S, 14-40% Mn, 0.005-0.300% N, 0.0005-0.2000% Bi and substantially the remainder Fe and, according to necessity, contains one or more of 7% or less Cr, 3% or less Al, 2% or less Nb, 3% or less V and, further, one or more of 0.02-0.2% S and 0.0005-0.05% Ca. In this composition, Bi is largely contributed in improving the of steel. Because, this high Mn-steel with this composition shows sufficient non- magnetic properties while is inexpensive and excellent in machinability, many applications can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high manganese steel with excellent machinability.In particular, the present invention relates to a high manganese steel with excellent machinability. In addition to having
This relates to a high manganese steel that has excellent machinability characteristics that are not found in conventional high manganese steels.

In recent years, there has been a demand for inexpensive non-magnetic steel that is not affected by magnetic fields as the main components of electromagnetic equipment such as transformers, superconducting magnets, motors, etc., as well as related components, including nuclear fusion experimental facilities and magnetic levitation high-speed trains. It has become.

Along with this, high manganese steel is attracting attention as an inexpensive non-magnetic steel to replace conventional austenitic stainless steel, and it has overcome the drawbacks of 73% Mn steel, known as Hatfield steel. A low carbon steel and a high manganese steel with a low coefficient of thermal expansion have been developed, which have stable non-magnetism without an increase in magnetic permeability after processing or heat treatment, and have a low coefficient of thermal expansion. However, conventional high manganese steels such as 73% Mn steel generally have extremely poor machinability, and even though the recently developed high manganese steels have excellent mechanical and physical properties. This has been a major obstacle in actual use.

The present invention eliminates the disadvantage of poor machinability of conventional high manganese steel! The object is to provide a high manganese steel with improved stiffness, and the above object can be achieved by providing the high manganese steel described in the claims.

That is, the present invention provides GO, O/~8 to T Stθ, 2
~3.0%+Mn/4'-yo%yNO,00k
-0.30%, and the remainder is substantially Fe, by adding Blo, oos~O, % to high manganese steel, which improves rigidity in terms of drilling performance and turning performance. and, if necessary, N1+ Or t
A high manganese material that greatly improves the machinability by adding at least one selected from AJ + Nb eV, and at least seven of S and Ca. It's about steel.

Next, the present invention will be explained in detail.

As a result of our dedication to research and development of high manganese steel in accordance with the purpose of the present invention, the present inventors decided to add B1 in θ, oos -o, -% to improve the machinability of high manganese steel. We have newly found that it is possible to obtain significant effects. Furthermore, together with B1, NllCr t AI + N
The present invention has been based on the new finding that machinability is significantly improved by adding a composite of at least 7 selected from b l V and at least 7 of straddle Ca and S. completed.

Next, the reason for limiting the component composition in the tree brother ψ1 will be explained.

C is an effective element for stabilizing the austenite phase and making it non-magnetic. If C is less than 0.07%, the above effect will not be seen, while if C is more than 82%, hot workability will decrease and cracks will easily occur during steel ingot rolling.
G l'j: o. It is necessary to keep it within the range of θ/~8.

Sl is an element necessary for deoxidation, and Sl is θ. If it is less than 2%, sufficient deoxidation will not occur, while S1 is 3°0%.
If the amount is more than 01, cracks will occur during rolling.
It needs to be within the range of 2 to 3.0%, especially when 81 is 0.
Suitable results are obtained when it is within the range of 0.2 to 0%,
Further, in order to increase the strength, it is preferable to add and contain more than 1.0% of Sl.

Mn is an indispensable element for stabilizing the austenite phase to make non-magnetic steel.If Mn is less than 79%, the austenite phase cannot be stabilized, whereas if it is more than 79%, Due to manufacturing difficulties, M
n must be within the range of //I-0%.

N is an element that has a large effect of stabilizing the austenite phase and making it non-magnetic, and also has a large effect of contributing to an increase in strength, and N is θ. If it is less than 0.005%, the above-mentioned effect cannot be obtained, and if it is more than 0.30%, the steel ingot becomes susceptible to cracking during rolling.
Must be within the range.

B1 is an element newly found by the present inventors to greatly contribute to improving machinability in the steel of the present invention, and when B1 is less than o or ooos%, no improvement effect on machinability is observed. , on the other hand, if O exceeds 1.2%, not only will the above-mentioned improvement effect be saturated, but also the cleanliness of the steel will be impaired, so B1 is θ,ooos~0. It is necessary to keep it within the range of λ%.

Ni y Or t AJ + Nb y '/ is high f
It is an element that contributes to improving the strength, toughness, corrosion resistance, etc. of f7 gun steel, but Ni r Or r kl + Nb
l At least 7 types selected from V are N
3% for 1, 7% for Cr1. If the amount is 3% for AI, 2% for Nb, and 3% for Since this will lead to an increase in the cost, it is necessary that the amounts of these elements added be below the above-mentioned contents.

It is conventionally known that S and Ca are elements that each contribute to improving machinability, but in the present invention, at least seven of S and Ca are added in combination with B1. The present inventors have newly found that machinability is further improved by adding 0.02% of S and 0.02% of C.
& is 0. If θOOS% is slightly higher than each other, the machinability improvement described above will not be achieved, while S is Ol, 2%, Ca
The cracking susceptibility of the steel ingot will increase if each of O and 01% is too large, so at least 7 types of S or Ca should be 0.0- to O0λ% for SK, and o, ooor for Ca.
It is necessary to keep it within the range of ~O1θS%.

Next, the present invention will be explained with reference to Examples.The present invention and conventional high manganese steels whose compositions are shown in Table 1 were melted and their machinability in terms of turning and drilling properties were investigated. Magnetic property was measured.

Conventional steel A shown in Table 7 is standard/? %Mn@, conventional steel B
contains Grg%/g%MZI steel, conventional steel C contains Or
It is a 1g% Mu steel containing 3%. On the other hand, Kinai Akiko/～
B is C. . The steel of the present invention is a 7g% Mn steel containing A%, the steel of the present invention L-2 was designed to improve machinability by adding only 81, and the steels of the present invention 3 to B contain Ca and S together with B1. The above-mentioned improvement is achieved by adding and containing a combination of the following. Invention steels 7 to 1 are 4t% Mn steels, and invention steels 3 to 3 are 30% Mn steels.

For each steel type shown in Table 1 above,
The machinability and perforation tests were conducted under the conditions shown in the table.
Furthermore, magnetic permeability was measured using a vibrating sample magnetometer. These results are shown in Table 7.

According to the same table, the magnetic permeability of the steels of the present invention is 80,021, indicating that they are substantially non-magnetic. In addition, the turning performance of the steel of the present invention has been greatly improved compared to conventional steel, and the drilling performance of the steel of the present invention has been improved, whereas it was impossible to drill holes with conventional steel. It can be seen that this has been greatly improved.

As described above, the steel of the present invention is made by adding an appropriate amount of B1 to the conventional high manganese steel, and further adding N:t to the conventional high manganese steel.
It is a steel containing at least one selected from t Or +'AI* Nb r V and/or at least one of S and Ca, and the steel of the present invention is superior to conventional high manganese steel. It has excellent machinability in terms of turning and drilling properties, and is the same as conventional high manganese steel in terms of non-magnetic properties. It is expected to have many uses as a non-magnetic steel with excellent properties.

Claims (1)

[Claims] 1, co, θ/to 8-%, Sto, 2-3. o%+
Mn#/-4IO%, No, oos-o, 3o
A high manganese steel containing o%r Bt o,ooos~0.2000%, the remainder being substantially better than Fe, and having excellent machinability. 2, Go,oo/~/, 2%+SiO,2
~3.0%+Mn/'l ~'10% + N O,
003~0.300% + Bi O,000! ;
”'-0,,2000%, and further contains Ni + C
Which one selected from ir + AI + Nb, V is one type or 2N or more and 3% or less in N soil.
7% or less for AI! 3% or less, Nb
Contains 2% or less in t■ 3% or less,
The remainder is essentially high manganese steel with superior machinability compared to Fe. 3, GO', 0/-/, 2%, SiO,;
t-3,0%+Mn/4'-'10%, No,
oos -o, too%+ Bi O,000! i～O
1-000%, and further contains at least 7 of S, ca, o, o, i~0.21% for S,
A high manganese steel with excellent machinability, containing o, oos to o, os% of Ca, with the remainder being substantially better than Fe. 4, co, o/~ha, 2%e Sto, x ~,
y, o%, Mn/ll~ke θ%+ No, oori~
Contains 0.300% + Biθ, Oθθ, too%, and further Ni + Cr + AI + Nb +
Any 7 or 2 or more types of Ni selected from V
What about? % or less, 7% or less for Or, AI
3% or less for Nb, 2% or less for ■, 3% or less for ■, and at least one of S and Ca.
O, 0, 2~O0a% for C & O
, ooos~θ, 05%, and the remainder is substantially less than Fe, which is a high manganese steel with excellent rigidity.