JP4143062B2 - Method for melting surface layer of metal material - Google Patents

Description

  The present invention relates to a melting treatment method capable of modifying a metal material surface layer by melting and resolidifying the surface layer of the metal material and adding other solute components, or obtaining a composite steel material.

For example, a technique shown in (Patent Document 1) has been proposed as a technique for modifying a metal material surface layer or manufacturing a composite steel material by melting and resolidifying the surface layer of a continuous cast slab of steel and adding other solute elements. ing. The technique of this (patent document 1) melt | dissolves the surface layer part of the steel slab surface by either one or both of induction heating and plasma heating, and carbon, silicon, manganese, phosphorus, sulfur, A solute element for changing the characteristics of steel such as nickel, chromium, molybdenum and copper is added and re-solidified.
JP 2004-195512 A

Although the technique disclosed in the above (Patent Document 1) has been recognized to be effective in achieving the object, it has been found that there is still room for improvement in terms of addition of solute elements. In other words, the solute element is directly supplied to the melting part in the form of powder or wire, but in the case of powder, it is supplied via a plasma torch, so that it is easy to scatter and difficult to supply stably. As a result, the yield is lowered, and in the case of direct addition of wires, the supply to the high temperature part is involved, so that there is still a problem that the stable supply is difficult.
An object of the present invention is to solve such problems. By supplying the solute component before melting, the solute component can be stably supplied and an appropriate amount of the solute component can always be added. It is another object of the present invention to provide a method for melting a metal material that makes it possible to satisfactorily modify the surface layer of the metal material or to obtain a high-quality multilayer material.

In order to solve the above problems, the method for melting a metal material according to the present invention melts the surface layer portion of the surface of the metal material while moving the metal material using heating by DC plasma oscillated by an AC magnetic field. In a method for modifying a surface layer of a metal material by adding a solute element to the melted surface layer portion and re-solidifying the particles, a particle containing a predetermined amount of the solute element is applied to the surface of the metal material before melting. It distributes and supplies to the both sides of the central line which is a metal material moving direction immediately under, It is characterized by the above-mentioned.
Further, in the present invention, the surface layer portion of the surface of the metal material is melted while moving the metal material using heating by DC plasma oscillated by an AC magnetic field, and a solute element is added to the melted surface layer portion. a method of modifying the surface of metallic material by resolidification, the part fraction plasma is irradiated, the particles containing the solute elements in a predetermined amount, is the center line metallic material moving direction immediately below the plasma torch You may distribute and distribute to both sides.
Further, in the present invention, the surface layer portion of the surface of the metal material is melted while moving the metal material using heating by DC plasma oscillated with an alternating magnetic field, and a solute element is added to the melted surface layer portion. a method of modifying the surface of metallic material by resolidification, both parts fraction the metal material surface and plasma before melting is irradiated, the particles containing the solute elements in a predetermined amount, immediately below the plasma torch The material may be distributed and supplied to both sides of the center line, which is the metal material moving direction.
In addition, in this invention, it is good also considering the addition position of the particle | grains containing a solute element as multiple places in the width direction on both sides.
In addition, in the present invention, particles containing a solute element may be intermittently supplied. As a result, the solute element can be uniformly added to the molten portion.
Particles containing a solute element can be mixed with gas or liquid and sprayed on the surface of the metal material before melting. In this case, the gas mixed with the particles containing the solute element contains a reducing gas such as nitrogen, argon, helium or hydrogen, and the liquid contains a polymer such as petroleum 3, class 4, LPG, polyvinyl alcohol or the like. Is desirable.

  According to the metal material melting treatment method of the present invention, an appropriate amount of solute element can be supplied in advance to the surface of the portion to be melt treated, and the amount of solute element required during actual melting can be added. The targeted good modification can be achieved, or a high quality multilayer material can be reliably produced. In addition, since the solute element is supplied in advance before the metal material is melted, the solute element can be supplied stably and uniformly.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The processing depth of the metal material melting processing section is determined by the heat supply conditions of the processing (current value of DC plasma, distance between processing target and torch, processing speed, etc.), and therefore the amount of solute element to be added is known in advance. be able to. Therefore, depending on the purpose of surface modification of the metal material, production of composite steel, etc., the necessary amount of the solute element is supplied in advance as a predetermined amount to the surface of the melt processing portion, which is necessary when the metal material is melted. Addition of solute element amount is possible.
FIG. 1A shows an intermittent supply system in which particulate solute elements are placed at regular intervals in the longitudinal direction of the metal material 1 before the melting treatment, and 2 is a plasma torch installed above the metal material 1. 3 is a plasma irradiation part by the plasma torch 2, 4 is a melted part generated by the plasma irradiation (becomes a resolidified part over time), 5 is a material moving direction, 6 is a center line including a torch width, 7 Indicates intermittent solute element addition positions. The addition position 7 has a symmetrical relationship with the center line 6 in between. By allocating a necessary amount of solute elements known in advance to a plurality of solute element addition positions 7 before melting of these metal materials, the melting process by the plasma torch 2 is started, so that the solute elements Is uniformly melted into the molten portion of the metal material to produce a modified portion of the desired material. As a means for supplying the particulate solute element to the target location, an arbitrary method such as a feeder form or a form in which the particulate solute element is previously fixed to a predetermined position of the metal material by any means may be employed.

In addition, in the method of supplying particles intermittently, it is necessary to pay attention to the following points. That is, the element supply position in the width direction orthogonal to the material melting processing direction is distributed to the left and right of this center line and added at two or more locations, assuming that the width of melting by a single plasma torch is 100 mm. Is preferred. This is because, as shown in FIG. 2, in the molten pool 4, a flow 11 rotating in both width directions from the center of the pool is generated due to surface tension-induced flow, and only if it is directly under one torch 2 or in the width direction of the molten pool. This is because if supplied to either end side, the solute element advects and diffuses only on one side, and the solute element segregates in the width direction. In the longitudinal direction of the material, the length to be melted and re-solidified varies depending on the processing conditions, but is generally about 10 to several tens of mm, and at least intermittently supplied at a pitch of about 10 mm also in the processing direction. preferable. In the figure, 9 indicates a vibrating plasma arc, and 10 indicates the vibration direction of an arc that is vibrated by an alternating magnetic field.
When the addition position 7 is distributed on both sides of the center line 6, the addition position is not limited to left-right symmetry, and the addition position can be slightly shifted in the longitudinal direction, or the addition position can be a plurality of positions on both sides in the width direction. What is necessary is just to select suitably according to quantity.

FIG. 1B shows an example in which a solute element is supplied to a predetermined portion of the metal material 1 before melting by a spray spray method, and 8 is a region where the solute element is added by spraying. Particles containing a solute element (may be powder in some cases) are mixed with an appropriate gas or liquid, and this mixture is sprayed onto the surface of the metal material 1 in advance by a spray nozzle or the like, and melted by the plasma torch 2. When the treatment is started, the solute element supplied by spraying is uniformly melted into the melting portion, and a modified portion of a desired material is obtained.
The gas to be mixed with the solute element is preferably one containing a reducing gas such as nitrogen, argon, helium, hydrogen, etc., and an appropriate gas and a solute element among these are mixed and sprayed onto the surface of the metal material. It is important to supply the spray so that it does not scatter.
The liquid to be mixed with the solute element is preferably one containing petroleum 3rd class, 4th class, LPG, polyvinyl alcohol or other polymer, and in this case, the mixture is sprayed onto the surface of the metal material by a spray nozzle or the like. And apply. In some cases, it is also possible to supply by a painting method without spraying.
When mixing with gas or liquid, the particle size of the solute element is advantageously finer because of the ease of mixing or nozzle spraying, but the particle size is not limited as long as the capability of the spray nozzle allows. .

As shown in FIG. 3, the direct current plasma is vibrated by two plasma vibration coils 16 disposed close to the plasma ejected from the plasma torch 2 toward the metal material 1. The two plasma oscillation coils 16 connected to the AC power source 18 are installed in the width direction of the metal material 1 so as to face each other with the plasma interposed therebetween, and the coil current flows in the metal material width direction. In the plasma, the torch 2 serves as a cathode and the metal material 1 serves as an anode via a direct power source 17. As shown in FIG. 4, an electron flow 13 is emitted from the torch, and a current 12 flows from the metal material 1 to the torch 2. . When an alternating magnetic field 14 is applied to the current by passing two plasma oscillation coils 16 in accordance with Fleming's left-hand rule, the front view of FIG. 3 is perpendicular to the plane of the drawing and the side view of FIG. Lorentz force is generated in the direction of, and the plasma is vibrated in the direction of arrow 10. Reference numeral 14 in FIG. 4 denotes an electromagnetic force that vibrates the plasma. As a result, as shown on the right side of FIG. 3, a fan-shaped flat plasma 9 spreading toward the material side is formed. Due to the vibration of the plasma and the movement of the material at a constant speed, the metal material is continuously melted in the longitudinal direction with a width corresponding to the amplitude.
What is necessary is just to supply a desired solute element with respect to the molten pool obtained in this way using the appropriate solute element supply means illustrated to Fig.1 (a) (b). In the example shown in the figure, the upper surface of the metal material placed horizontally is shown as being melted. However, the metal material is not limited to the horizontal state and can be assumed to be in a vertical posture or inclined. Needless to say, the present invention can be similarly applied to both cases.

In the present invention, as shown in the figure, a predetermined amount of a solute element is supplied in advance to a portion to be melted in the surface layer of a metal material such as a moving continuous cast slab, and then DC plasma is vibrated in the material width direction. Therefore, it is aimed to melt and resolidify the portion supplied with the solute element to be reformed. Specifically, the content of the modification is to reduce the variation of the supplied solute elements in the molten pool to improve the properties of the surface layer at a certain depth, to prevent cracking and increase the strength, and to improve the workability For example.
In addition, the present invention not only simply modifies the surface layer but also actively supplies a specific solute element to the molten pool, thereby making this part a metal material different from the other parts. As a result, it is possible to manufacture a multilayer material having a composite function. For example, by supplying a predetermined amount of nickel and chromium to the surface layer of a low carbon steel material in advance and melting and resolidifying this part, the surface layer part is a stainless steel with excellent corrosion resistance, and the base part is a complex steel Material is obtained.

  Examples of solute elements to be supplied and added before melting in the present invention include carbon, silicon, manganese, phosphorus, sulfur, nickel, chromium, molybdenum, copper, silver, aluminum, magnesium, rare earth elements, and the like. These are supplied and added alone or in the form of a plurality of alloys of these components. Moreover, depending on the case, it can be added in the form of a compound of a solute element to be added and oxygen or nitrogen.

  A DC plasma torch is placed above a continuous cast slab of 150 mm wide and 100 mm thick, and the distance between the torch and slab is 100 mm, the DC current is 300 A, the AC magnetic field is 50 Hz, and the effective value of the magnetic flux density is 3 mT. The surface of the slab was melted with a width of about 100 mm by vibrating the plasma. The processing speed (= slab moving speed) was 0.1 m / min. As a solute element, 5% by mass of nickel as a solute element was previously supplied as particles at 10 mm pitches in the longitudinal direction at positions 10 mm on both sides immediately below the torch in the slab width direction. As a result, a surface layer-modified slab was obtained in which the variation in nickel concentration in the slab width direction and length direction was 10% or less and a solute was added up to a depth of 5 mm.

  A DC plasma torch is placed above the continuous cast slab of aluminum killed steel containing 1% by mass of copper with a width of 150 mm and a thickness of 100 mm. The distance between the torch and the sample is 100 mm, the DC current is 300 A, the AC magnetic field is 50 Hz, and the magnetic flux density. The slab surface layer was melted at a width of about 100 mm. The processing speed was 0.3 m / min. As an solute element, nickel powder having an equivalent weight of 1% by mass, which is an element that suppresses cracking of the steel material by copper, was previously sprayed in the width direction of the slab and melt-treated. As a result, a surface layer-modified slab was obtained in which the nickel concentration variation in the slab width direction and the length direction was 5% or less and 1 mass% nickel was added up to a depth of 3 mm.

A DC plasma torch is placed above the low cast aluminum killed steel continuous cast slab with a width of 150 mm and a thickness of 200 mm. The surface of the slab was melt-treated with a vibration of about 100 mm. The processing speed was 0.075 m / min. At this time, the melt depth was 10 mm. As a solute element, 18% by mass of chromium was supplied in advance to the portion irradiated with plasma as particles in a slab width direction so that the pitch was 5 mm with the center line just below the torch. As a result, a composite steel material was obtained in which variation in chromium concentration in the slab width direction and length direction was 0.5% or less, a depth of 10 mm was stainless steel, and the inside was plain steel.

The embodiment example for demonstrating the surface layer melting processing method which concerns on this invention is shown, (a) is an example which supplies solute element particle | grains intermittently to the material surface before melting, (b) is a solute element gas or The example which mixes with a liquid and is spray-supplied to the material surface before a fusion | melting is shown. It is explanatory drawing which shows the state which segregates by the method of supply of a solute element, when implementing the melt processing method of this invention. It is the front view and side view which show the specific example of the vibration means of the DC plasma used in this invention. It is a figure for demonstrating the principle which the vibration of the plasma of FIG. 3 produces.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Metal material 2 Plasma torch 3 Plasma irradiation part 4 Melting part 5 Material movement 6 Symmetrical line including torch width 7 Intermittent solute element addition position 8 Solute element addition position by spray 9 Plasma arc in vibration 10 Arc vibration by AC magnetic field 11 Flow in Molten Pool 12 Current 13 Electron Flow 14 AC Magnetic Field 15 Electromagnetic Force 16 Plasma Vibration Coil 17 DC Power Supply 18 AC Power Supply

Claims (5)

The metal material is obtained by melting the surface layer portion of the surface of the metal material while moving the metal material using heating by direct current plasma oscillated by an alternating magnetic field, and adding a solute element to the melted surface layer portion to resolidify it. In the method of modifying the surface layer of the above, the particles containing a predetermined amount of a solute element are distributed and supplied to both sides of the center line, which is the direction of movement of the metal material immediately below the plasma torch, on the surface of the metal material before melting. A method for melting a surface layer of a metal material. The metal material is obtained by melting the surface layer portion of the surface of the metal material while moving the metal material using heating by direct current plasma oscillated by an alternating magnetic field, and adding a solute element to the melted surface layer portion to resolidify it. a method of modifying the surface of the part fraction plasma is irradiated, the particles containing the solute elements in a predetermined amount, and distributed to both sides of the central line is a metal material movement direction immediately below the plasma torch, supplied A method for surface layer melting treatment of a metal material. The metal material is obtained by melting the surface layer portion of the surface of the metal material while moving the metal material using heating by direct current plasma oscillated by an alternating magnetic field, and adding a solute element to the melted surface layer portion to resolidify it. a method of modifying the surface of both parts fraction the metal material surface and plasma before melting is irradiated, the particles containing the solute elements in a predetermined amount, is a metal material movement direction immediately below the plasma torch A method for surface layer melting treatment of a metal material, characterized by being distributed and supplied to both sides of a center line.   The method for melting a surface layer of a metal material according to any one of claims 1 to 3, wherein the addition position of the particles containing the solute element is a plurality of positions on both sides in the width direction.   The method for melting a surface layer of a metal material according to any one of claims 1 to 4, wherein particles containing a solute element are intermittently supplied.

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