JPS60208418A - Production of thick steel plate having high magnetic permeability for structural member - Google Patents

Abstract

PURPOSE:To obtain a thick steel plate having mechanical characteristics and high magnetic permeability in combination by subjecting a billet contg. specific wt% of C, Si, Mn, sol. Al, etc. to hot rolling at a prescribed temp. and draft then allowing the rolled plate to cool. CONSTITUTION:A billet or casting billet consisting of 0.005-0.15% C, 0.15- 1.50% Si, 0.60-2.00% Mn, <=0.050% P, <=0.010% S, 0.010-1.00% sol. Al, <=0.008% N, <=0.010% O and the balance Fe with impurities is heated to 1,050- 1,250 deg.C and the hot rolling is finished under the conditions of <=50% cumulative draft at 975 deg.C- finishing temp. and >=850 deg.C finishing temp. then the rolled plate is allowed to cool. The plate is once heated to the temp. of Ac3 point or above and is then allowed to cool according to need. The coarse grains of <=#6 ferrite grain size are obtd. by the above-mentioned compsn. and treatment by which mechanical and magnetic characteristics of >=1,000 max. magnetic permeability, 41kgf/mm.<2> tensile strength, etc. are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to I! ′! , a method for manufacturing a thick steel machine for a magnetic permeability structural part 44, especially a structural part ("), which has a high magnetic permeability structure without having the I211 function of an electromagnetic iron core or a magnetic lead. Part IA Aikawa °l Concerning the manufacturing method of steel handling.

(Junai Technique i + 1) City (6 stone iron core or magnetic shielding function 7
'It is necessary to have crystalline magnetic permeability, but /
The means to ensure the strong LL and toughness required for the J structural part 10 and 7 are often contradictory to the metallurgical T stage by increasing the active & 1 (・1 and 2. For example, to increase the strength increase,
Also +, c++'+? ! :Toward 1-1, it is a rational method to make the MitsuU structure finer, but all of these methods lower the iB Ml rate.

Thick inner steel plates using high magnetic permeability structure are used for large-scale experimental equipment such as CYCULON, electromagnet iron core Aoi of nuclear fusion equipment, and magnetic core 1, etc., and are used in the nearby 6I
In order to further develop the results of large-scale F1 studies, it is necessary to develop a mechanical +4 that is originally contradictory to the thick handling section H! I
At present, there is a strong desire for a material that satisfies both magnetic properties such as magnetic properties, magnetic permeability, and magnetic flux density.

For example, the conventional 40 kgf/nlA class master tune 1
&(more than 1 yen), its maximum magnetic permeability is at most 0110, and the magnetic flux density in a magnetic field of 50008/m is also at most 1.50'T"j"a-9(, such magnetic The 4H nature meets the above-mentioned demands of 1).The 2nd point cannot be made.

(Objective of the Invention) The object of the present invention is to create a large-scale scientific experiment device or nuclear fusion device by combining stages to ensure a certain level or higher as a structural member and a high magnetic permeability double phase. An object of the present invention is to provide a method for manufacturing a high-permeability thick-walled steel plate for structural members, which can be used for electromagnet iron cores or magnetic shields and can greatly contribute to securing energy for mankind.

(Summary of the Invention) As a result of various studies to achieve the above-mentioned object, the present inventors found that: ① Since the presence of cementite or pearlite is undesirable in order to obtain high magnetic permeability, it is necessary to contain C as much as possible. 1fft is reduced, and the associated strength decrease is 3 plates and s.
The addition of so1.A (2 and Si can compensate for this; ■ The ferrite grain size should be made as coarse as possible within the range where toughness does not become a problem as a structural member; ■ The addition of so1.A (2 and Si will reduce the strength. There is an appropriate range for not only compensating for the Not only does it measure whether mechanical dynamics is satisfied, but it also measures magnetic properties such as magnetic permeability.
The present invention has been completed by discovering that the same can be maintained.

Please note that Figure 1 does not show the effect of C content on the magnetic permeability and strength of 0.253i -0.40A (1'°C) steel, but as the C ratio r=i fit increases, the strength increases. It can be seen that the magnetic permeability of the double press is low. Figures 2 and 3 show the Si content of 0.05C5i-0,3AQ steel and 0.05C-0,2551-M' steel, respectively. The amount and sol, including AQ, show an influence of 1 on the magnetic permeability and strength.It can be seen that as the Si content increases, the maximum magnetic permeability μl× increases and the coercive force 11c decreases.Increasing the Si content This improves the magnetic properties of these materials, and increases the mechanical strength of the mechanical properties. Comfortable living is extremely important.

r, olA (!), a similar effect to Si was observed, S01, AU joint: [1,
weak! 1 degree rises to 2 and 1 person 1-111 goes to L. Zunawara, the maximum magnetic permeability μIIIax increases
．． Nozuki 1c is low F! l-ru.

In addition, in order to make the ferrite grain size inorganic, it is important to coarsen the austenite grain size, and for this purpose, during hot rolling,
By setting the cumulative downstream ratio of 975°C to finishing temperature to 50% or less and setting the finishing temperature to 850°C or higher, the ferrite i/particle size can be sufficiently increased by 1.

Thus, the present invention has the following properties by weight: C: 0.005-0.15% Si: 0.15-0.15%
1.50%, Mn: 0.60-2.00%, P:
0.050% or less, s:o, o+o% or less, sol,
Eight I: 0.010-1.00%, N: 0.00
8% or less, Oxygen: 0.010% or less, further as necessary, Nb: 0.015 to 0.250%, V:
0.015-0.500% and Ti: 0.015
At least one selected from the group consisting of ~0.250%,
A steel slab or cast slab with a steel composition consisting of the balance Fe and unavoidable impurities is 1050 to 1250
°(:), hot rolling is carried out under the conditions of 975℃~finishing temperature with a cumulative reduction rate of 50% or less and a finishing temperature of 850℃ or higher, and then after finishing the P-rolling, as necessary. A magnetic flux density with a maximum iJ & Pi ratio of 1000 or more and a magnetic field of 50008/2, characterized by heating to a temperature of C3 or higher and then cooling it to make coarse ferrite grains with number 6 or less. 1.60T or more, tensile strength 41kgf7' product, yield strength 25kgf/mF L, Charpy absorbed energy (1'(: C2,8k
gf m u Lt' is l(it is the structure part ((for IV
This is a demonstration of steel plate manufacturing.

According to the present invention, the ferrite grain size number! ]6
III F with a suspension of 1.>, the maximum permeability is 1000
That’s all for magnetic J! 15 f) OOha/'I11 F62.8
00), both speed density is 1.60'F or more, and tensile strength is 41 kgr/. 1 Fui'', ruggedness strength 25 kgf, / quantity -1, 2 dragon V notch absorption energy 2゜1 at 0°C
(kgf +n to l)J Unique mechanical properties and magnetic 1'1. If both rr and rr are satisfied, 1 yen # and 1 treatment for high magnetic permeability grooved shrines are tll ('+reru no (mountain).

(Image of the invention) Hereinafter, the steel composition and each manufacturing process according to the invention will be described.
State the reason for the limitation in 1.

c lj: , 11. A low force is preferable to pass the '6th', but 1, B (<1','),!:
Structural part (,1)
``C1 of l, invention (is 0-containing negative ■ F limit of 0.005
? o, f : f L, < is 0. Old % and 4 Otsu. ] The second limit is magnetic Il! l character and 'ltsu] + 'l, considering 0
．． 1596 and 4. In addition, hot rolling 1'! 1,1 in order to reduce the amount of parts C
, according to the invention, the zero content is 0.09% or more 1'h<
desirable.

Adding 0.15% or more of Si increases the strength and improves the magnetic properties, but if it increases too much beyond the appropriate amount, the toughness deteriorates υ and the saturation magnetic flux density decreases -υ, so the Si content is 0. .15-1.5%, preferably 0.20-1.
It was set at 50%. Note that it is desirable that C be 0.09% or less and Si be 0.40% or more.

Adding Mn in an amount of 0.60% or more prevents hot embrittlement caused by S and improves toughness, so it is necessary to add Mn in an amount of 0.60% or more, but if it is added in an amount exceeding 2.00%, the magnetic properties will deteriorate. Therefore, in the present invention, the Mn content is limited to a range of 0.60 to 2.00%.

P deteriorates the mechanical properties, forming a dense segregation zone especially in the center of the CC slab and causing two plates, etc., so it is preferable to keep it low, but the removal of P always involves an increase in cost. .050% or less.

S forms MnS and has rolling anisotropy of mechanical properties 1! It must be limited to 0.010% or less because it causes I and deteriorates ductility and toughness in the direction perpendicular to rolling.

sol, AQ is 0.010% or more, preferably 0.01
Addition of 5% or more renders solute N harmless and increases magnetic permeability due to the effect of solid solution AQ, but addition of more than 1°00% deteriorates the flow during steelmaking and makes the plate resistant. Is it deterioration? ；° Therefore, in the present invention ゛(
is 0.01() ~1.00! ! 6, preferably 0.
015 to 0.80%.

It is desirable that the N content be as low as possible, particularly 0.008%, preferably exceeding 0,00%. U□(I
-Powder, i ¥ becomes 11111 people (Kunaotsu no Go 0.00
8% or less, preferably 1.1.0, DO (i 96 or more -1).

Cup (5 is jl, toku B+'i thing is formed 3' le 0.)
't1', 0. (It must be 1105'6 or more F, preferably 0.005!16 or less.

In order to stably reduce the rate of 1Tli to IB7, the above basic components must be met; Nb: O, +115~
0.250%, ■: 0°015~0.5tltl 9 stones and Ti: 0.015~0.250%,
It is also good to further contain one or more selected from J11'.

In other words, when Nb is added in an amount of 0.015% or more, it combines with C and N to form large Nb' (C,N), and the external magnetic field 11 = IIc (coercive force) is near the B-11 curve. It has the effect of increasing the differential permeability at -4.
Although c is increased, the external field increases the differential permeability near the field It -11c, resulting in a so-called square 1m history 13-II curve. However, if Nb is added in an amount exceeding 0.250%, surface cracking of the slag will occur significantly, so when Nb is added, it is limited to 0.015 to 0.250%.

By adding 0.015% or more, (2) combines with C and N to form V (C,N), which increases the differential permeability in the vicinity of the external magnetic field 11 = tlc, similar to i'Nb. , but 0
．． If added in excess of 500%, the damage to the 21st stroke would be significant, so it was limited to a range of 0.015 to 0.500%.

When Ti is added in an amount of 0.015% or more, it combines with C and N to form Ti (C,N) and increases the differential permeability in the vicinity of the external magnetic field H-llc, similar to Nb and ■.
If it is added in excess of 0%, the toughness will be significantly deteriorated.
The range was limited to 0.015 to 0.250%.

Next, in the method according to the present invention, the heating temperature before hot rolling is set to 1050°C, preferably 1150°C or higher, so that the austenite grain size is equal to In addition, the cumulative reduction rate at the finishing temperature of 975'C to 50% or less, and the finishing temperature of 850°C.
The above is t■ of austenite grain size number 6 or less.
This is to make it grow into grains.

In addition, in order to further increase the magnetic permeability, it is possible not only to use the rolled product as described above, but also to heat it to a temperature of 03 or higher, for example, 850°C or higher, to undergo transformation and sintering. It is also possible to eliminate the internal strain by breaking the consistency with the nitride or carbide matrix.

'J: Example A series of test steels shown in the table below were subjected to continuous casting (blue steel IA was heated to 1100'c by PJ) and 4 production strips (' 11- Thickness 25 ■ Light I!'lI
When the magnetic permeability steel was manufactured, mechanical properties 1 as shown in the same table 1! I, &H's mood characteristics were a little off.

(1γ pull to Qri Jl)
When the C content is high as in the case of
Hagi, F4. available.

There is a fu C. 2 hmm ? G’c (wt%) Figure 2 S; [(wt≠) Figure 3 5olA1+1 (Wtφ)

Claims (2)

[Claims] (1) Tun F11% C1 C: tl, 0 (0.1596 to 15 Si: 0.
1.5-1.50!16, Mn: 0. (i(1~2
．． 0 (196, r': 0.050% or less, S: 0
．． 010% or more 1;, sol, ^l: 0.010-1
．． 00%, N: 0.008% or more 1", Oxygen: 0.
010% or less, and also P, Lih, Nb:
0.015-0.250%, V: 0. fl15~
0, 500% and Ti: 0.015-0.25
At least one selected from the group consisting of 0%, remaining 1? (
・Steel of illumination composed of unavoidable impurities
The temperature was heated to 250°C for 1 time, and the cumulative reduction rate at which the temperature reached 75° (~1) was 5 (196 or less, the temperature was 8).
50 'C or less' - article + '+, P C ratio is 11,
Next (: 1.'lE end rf & let it cool down 11 7" 16. 1-4 Φ degree number 6 and below 4"
111 conscription J to make it 11 grains? Maximum permeability 1
0flo -1-1 magnetic field 5000Δ/Ill This K1
．． >lj i; I-11, fio 1' or more, and tensile strength 41kgf/, l1m, yield strength tI 25kg
f/u! Below L, Charpy absorbed energy 0° (:
A method for producing a thick steel plate for a structural member with high magnetic permeability of 2.8 kgf m or more. (2) At section I6, c: 0.005-0.15% Si: 0.15
~1.50%, Mn: 0.60~2.00%, P
: 0.050% or less, s:o, 010% or less, sol
, 8 I: 0.010-1.00%, N: 0.0
013% or less, oxygen: 0.010% or less, further as necessary, Nb: 0.015 to 0.250%, V
: 0.015-0.500% and Ti: 0.0
A steel slab or cast slab with a steel composition consisting of at least one selected from the group consisting of 15 to 0.250%, the balance being Fe and impurities 1050 to 1250%
After heating, rolling is performed under the following conditions: 975°C to finishing temperature, the cumulative reduction rate is 50% or less, and the finishing temperature is 850°C or less, and then the hot rolling is completed (&... D
Ac, characterized by a coarse grain size of Fephite grain size number 6 or less and 4 degrees by heating it to a temperature of 1 unit and then letting it cool, a maximum magnetic permeability of 1000 or more, and a magnetic field of 5000Δ/
m'ii' magnetic flux thunderbolt 1.60T or more and tensile strength 4
1 to 8f/IJl, yielding strong electric current 25kgf/l+! Above, Charpy absorbed energy Q'C is 2゜8 kg
A method for manufacturing a 1 yen steel plate for use in a building opening with a high magnetic permeability of f-m or more.