CA1056427A - Electroslag melting of shaped castings - Google Patents
Electroslag melting of shaped castingsInfo
- Publication number
- CA1056427A CA1056427A CA224,980A CA224980A CA1056427A CA 1056427 A CA1056427 A CA 1056427A CA 224980 A CA224980 A CA 224980A CA 1056427 A CA1056427 A CA 1056427A
- Authority
- CA
- Canada
- Prior art keywords
- fused
- base plate
- slag bath
- melting
- plant
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D23/00—Casting processes not provided for in groups B22D1/00 - B22D21/00
- B22D23/06—Melting-down metal, e.g. metal particles, in the mould
- B22D23/10—Electroslag casting
Abstract
ABSTRACT OF THE DISCLOSURE
A method and plant for the electroslag melting of shaped castings by remelting a consumable electrode in a slag bath with the concurrent fusing of an element, at the initial stage the fusion process is carried out by introducing the element to be fused into the slag bath to 0.2-0.5 of the depth of the slag bath by using a consumable electrode with a cross section that is at least equal to that of the element being fused. The use of the above outlined method and plant make it possible to diminish materially the production costs in making shaped castings and to rule out welding from a technological process.
A method and plant for the electroslag melting of shaped castings by remelting a consumable electrode in a slag bath with the concurrent fusing of an element, at the initial stage the fusion process is carried out by introducing the element to be fused into the slag bath to 0.2-0.5 of the depth of the slag bath by using a consumable electrode with a cross section that is at least equal to that of the element being fused. The use of the above outlined method and plant make it possible to diminish materially the production costs in making shaped castings and to rule out welding from a technological process.
Description
10564~7 The present invention relates to electrometallurgy and more particularly to a method of electroslag melting of shaped castings and to a plant for effecting said method.
The present invention may prove to be most advantageous in mechanical engineering for producing parts and units which must meet stringent quality requirements, such as blanks for covers and bodies of fittings for atomic power plants, rolls for cold rolling mills, crankshafts, T-pieces and connecting rods intended to re-place forged or forged-and-welded constructions of similar designa-tion. The first lots of rolls for cold rolling mills produced on an -industrial scale from the metal obtained by the electroslag melting technique and tested under service conditions have proved that the service life of such rolls has been extended almost 2 or 3 times.
High quality and homogeneity of metal of ingots obtained by the electroslag process have suggested an idea about the possi-bility of using cast mill rolls produced by the electroslag re-melting technique in shaped molds.
Methods for producing blanks for, e.g., mill rolls, by the electroslag remelting techniques, in which a single or a plura-lity of metal electrodes are melted one after another in slagbaths, are known in the art. In the known methods, melting is accomplished at least in two cooled molds of different cross sections mounted one above another on individual jack carriages.
The ja~k carriages are capable of moving vertically along masts.
The disadvantages of these methods and the above-described plant is that, when producing blanks differing in cross section, it is necessary to use different electrodes for each cross section. Replacing the electrodes during the melting process causes shutdowns which adversely affects the quality of metal of the blanks being melted. Moreover, in the course of melting, the amount of slag should be varied - increased or decreased - which causes inconvenience in servicing the casters.
., . i,.
Methods of melting mill roll blanks by the electroslag remelting technique in a mold whose diameter corresponds to that of a roll barrel are more suitable. An element to be remelted, corresponding in shape and size to a roll neck, is set up in the mold on the base plate side and is fused to a base of the blank at the beginning of the process. The mold base plate has an opening whose diameter corresponds to that of the element being fused and forming the roll neck. The base plate is split vertically into two parts under which are mounted current-carrying prisms.
However, the above method and plant do not provide the required quality in the fusion zone where the element being fused is fused to the blank. Moreover, since the base plate is split verticall~ into two parts, it is warped owing to thermal expan~ion of the element being fused upon heating, and after the first heat the opening does not correspond anymore to the initial diameter of the element being fused. The resulting gap should be sealed to preclude the effluence of molten flux and metal. Thus, from one heat to another the gap between side surfaces of the base plate and the element being fused becomes larger, which eventually results in a rapid failure of the base plate. Such plants are inconvenient in servicing.
It is an object of the present invention to overcome the above disadvantages.
Another object of the present invention is to provide a method and plant which will provide a guaranteed quality of fusion of elements to a casting body, more convenient servicing of the plant and extending the service life of a base plate.
The objects are achieved in accordance with an embodi-ment of the invention wherein, in a method of electroslag meltingshaped castings by remelting a consumable electrode in a slag bath with the concurrent fusing of an element, there is provided
The present invention may prove to be most advantageous in mechanical engineering for producing parts and units which must meet stringent quality requirements, such as blanks for covers and bodies of fittings for atomic power plants, rolls for cold rolling mills, crankshafts, T-pieces and connecting rods intended to re-place forged or forged-and-welded constructions of similar designa-tion. The first lots of rolls for cold rolling mills produced on an -industrial scale from the metal obtained by the electroslag melting technique and tested under service conditions have proved that the service life of such rolls has been extended almost 2 or 3 times.
High quality and homogeneity of metal of ingots obtained by the electroslag process have suggested an idea about the possi-bility of using cast mill rolls produced by the electroslag re-melting technique in shaped molds.
Methods for producing blanks for, e.g., mill rolls, by the electroslag remelting techniques, in which a single or a plura-lity of metal electrodes are melted one after another in slagbaths, are known in the art. In the known methods, melting is accomplished at least in two cooled molds of different cross sections mounted one above another on individual jack carriages.
The ja~k carriages are capable of moving vertically along masts.
The disadvantages of these methods and the above-described plant is that, when producing blanks differing in cross section, it is necessary to use different electrodes for each cross section. Replacing the electrodes during the melting process causes shutdowns which adversely affects the quality of metal of the blanks being melted. Moreover, in the course of melting, the amount of slag should be varied - increased or decreased - which causes inconvenience in servicing the casters.
., . i,.
Methods of melting mill roll blanks by the electroslag remelting technique in a mold whose diameter corresponds to that of a roll barrel are more suitable. An element to be remelted, corresponding in shape and size to a roll neck, is set up in the mold on the base plate side and is fused to a base of the blank at the beginning of the process. The mold base plate has an opening whose diameter corresponds to that of the element being fused and forming the roll neck. The base plate is split vertically into two parts under which are mounted current-carrying prisms.
However, the above method and plant do not provide the required quality in the fusion zone where the element being fused is fused to the blank. Moreover, since the base plate is split verticall~ into two parts, it is warped owing to thermal expan~ion of the element being fused upon heating, and after the first heat the opening does not correspond anymore to the initial diameter of the element being fused. The resulting gap should be sealed to preclude the effluence of molten flux and metal. Thus, from one heat to another the gap between side surfaces of the base plate and the element being fused becomes larger, which eventually results in a rapid failure of the base plate. Such plants are inconvenient in servicing.
It is an object of the present invention to overcome the above disadvantages.
Another object of the present invention is to provide a method and plant which will provide a guaranteed quality of fusion of elements to a casting body, more convenient servicing of the plant and extending the service life of a base plate.
The objects are achieved in accordance with an embodi-ment of the invention wherein, in a method of electroslag meltingshaped castings by remelting a consumable electrode in a slag bath with the concurrent fusing of an element, there is provided
2 -the improvement comprising: introducing the element being fused into the slag bath to 0.2 - 0.6 of the depth of the slag bath at the initial stage of the fusion process.
The melting process effected in the above manner ensures the uniform fusion of the end face of the fused element introduced into the slag bath and guaranteed fusion of this element to the casting body both along its outline and over its cross section.
According to the invention, the fusion process is pre-~' ferably accomplished in the initial period by using a consumable electrode with a cross section that is at least equal to that ofan element being fused.
In this case the droplets of remelted metal fall onto an already fused surface of the element being fused ensuring thereby the guaranteed quality of fusion.
In accordance with one embodiment, there is provided, in a plant for the electroslag melting of shaped castings by electro-slag remelting of consumable electrodes in a cooled mold mounted on a base plate having an aperture through which an element to be fused in the course of melting is inserted, the improvement being in that the base plate is of a composite construction split along vertical planes, and that the molding part of the base plate comprises at least three sections, resilient members connected to each of said ,sections for forcing the sections against each other and against the element being fused; said mold adapted to accommodate a consumable '~ electrode connected to a power source' means for the vertical ' movement of the element being fused, said means adapted to insert ; the element into the slag bath through the aperture in said base plate; and current-carrying jaws movable in the horizontal plane, said jaws being connected to means adapted to urge them against the element being fused and having electric contact with said power source.
The means for vertical movement being adapted to introduce ~9~ - 3 -- 10564~7 the element being fused into the slag bath to a height ensuring its high-quality fusing to the casting body and facilitating the servicin~ of the plant.
The current-carrying jaws movable in a horizontal plane and fu~nished with the gear for urging them to the element being fused provide a reliable electrical contact and are simple and dependable in operation.
The use of the base plate molding part made up of at least three sections, of which each is coupled with the resilient clamping member, makes it possible to rule out the warping of the base plate due to thermal expansion of the element being fused, to enhance the plant reliability and to extend the service life of the base plate.
According to the present invention, each base plate section can be fitted with a heat-removing renewable insertion piece positioned in the place of contact with the element being fused, with the insertion piece height being at least equal to the radius of the element being fused.
The provision of each base plate section with a heat-removing renewable insertion piece disposed in the place ofcontact with the element being fused enables quick readjustment when passing over from melting a casting with a fused element of one type size to that with another one.
The height of the insertion pieces should be not less than the radius of the element being fused since it ensures it cooling and precludes thereby the burning through of its walls -~ at the initial moment of the melting process, and the runout of molten slag and metal.
According to the invention, the joints of the base plate sections are preferably stepped.
The above embodiment precludes the effluence of the mol-ten slag and metal along the base plate joint at the initial moment ' ,, :`',?`
, .
10564~7 o~ the melting process owing to thermal expansion of the element belng fused, when the base plate sections are displaced relative to one another.
The use of the herein-proposed method and plant for effecting the method materially lowers the production costs in the manufacturing of shaped castings by using the electroslag melting technique and by fusing together individual elements. It also makes it possible to avoid welding. The above outlined procedure and plant are suitable for enlarging castings by using precast or prefabricated (by any other now~existing method) blanks as elements to be fused. Moreover, when using the present invention a considerable saving is provided owing to improved performance characteristics of metal and better quality of castings.
The nature of the invention will be clear from the following detailed description of its particular embodiments to be had in conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic diagram illustrating the electroslag melting process;
Fig. 2 is a schematic diagram of a plant for effecting the proposed method, Fig. 3 is a general axonometric view of a plant for effecting the proposed method of the electroslag melting of shaped castings, and Fig. 4 is a section through IV-IV of Fig. 2.
The herein-proposed method of electroslag melting shaped castings consists essentially of introduclng a consumable electrode 1 (Fig. 1) into the melting space of a mold 2 and mounting an element to be fused 3 in the opening of a base plate 6 coaxially with the consumable electrode 1. Next molten slag is poured into the mold 2 to establish a slag bath 4 of a required height and, by passing an electric current from a power source 5 through an electric circuit cor.sisting of consumable ~'";' .
, -,. : .
electrode 1, slag bath 4 and element to be fused 3, the process of electroslag melting is initiated. In the initial period, the fusion process should be carried out by introducing the element 3 being fused into the slag bath a depth 0.2-0.6 of the depth of the slag bath.
To illustrate the requirements of such an arrangement, the slag bath is considered as a sum of resistances R, such that:
total Rl+R2+R3' where:
Rl is the resistance of poles of the consumable electrode 1 and the element to be fused 3 R2 and R3 are the resistances of poles of the consumable electrode 1 and the base plate 6" (on both sides of consumable electrode 1);
and Rtotal is the total resistance of slag bath ~.
For the sake of simplicity the consumable electrode 1 and element to be fused 3 are assumed to be arranged symmetrically within the melting space of the mold 2. Then R2 may be considered to be equal to R3.
With a constant input electric power fed to the slag bath 4 from the power source 5 a change in spacing ~ between the electrode 1 and the element 3 will cause a redistribution of electric power in the slag bath 4, with the power value changing most intensively in the resistance Rl since the resistances R2 and R3 are almost equal and vary negligibly at a change in the depth of introduction of the element 3 into the slag bath 4. A maximum specific electric power is released along the end face edges of the consumable electrode 1 and element 3. As the spacing ~ be-tween the electrodes decreases, i.e. when the introduction increment ~ of the element 3 becomes larger, the amount of the electric current passing through the element 3 increases, enhancing thereby the rate of fusing of the end face of the element 3 and, hence, s ~ ~ - 6 -....
.
providing better quality of fusion.
Moreover, an increase in the rate of fusion of the end face of the element 3 resulting from a larger introduction incre-merlt a ~ of the element 3 fed into the slag bath 4 is attributable to an increase in the contact surface area of the element 3 and the heated slag bath 4.
Thus, the deeper the element 3 is introduced into the slag bath 4, the better its fusion with the casting body.
However, with a small interelectrode spacing ~ the electroslag process is converted into an arc process, a feature which restricts the introduction increment a 4 of the element 3 to not more than 0.6 of the depth of the slag bath 4.
When the element 3 is introduced into the slag bath 4 to a distance less than 0.2 of its depth, a metal bath established by melting the consumable electrode 1 comes in contact with the element 3 being fused along its still unfused surface, which does not ensure high-quality fusion of this element.
When the electroslag melting process is accomplished in its initial period with a consumable electrode 1 of a cross section that is equal to or exceeds that of the element 3, the drop metal transfer of the consumable electrode 1 occurs in such a way that the droplets of remelted metal fall on an already fused surface of the element 3, forming a common metal bath along the element out-line. This ensures high-quality fusion of the element 3 with the casting body.
The use of a consumable electrode 1 with a cross section smaller than that of the element 3 results in the droplets of electrometal falling on yet unfused surface on the end face of the element which does not provide high-quality fusion.
Considered hereinafter is a plant ensuring the electro-slag melting of shaped castings with the concurrent fusing of individual parts during the melting process.
,~,.:-- -A plant for the electroslag melting of shaped castings comprises a consumable electrode 1 (Figs. 2 and 3) introduced into the melting space of a cooled mold 2, and an element to be fused 3 that is extended into a slag bath 4 from below. The consumable electrode 1 and element 3 are connected to a power source 5.
The mould is mounted on a base plate 6 with an opening ali~ned axially with the consumable electrode 1 and adapted to receive the element 3 which is fed from below into the opening.
The element 3 is set up on the top stage of a vertical transfer gear 7 fixed under the base plate 6 on a supporting plate 8, whereupon said element 3 is introduced with the help of the above gear 7 into the melting space of the mold 2. As for a drive of the gear 7, any known means - electromechanical, hydraulic, pneumatic, manual, etc., can be employed.
An electric current is passed to the element 3 by means of current-carrying jaws 9 movable in a horizontal plane and coming in direct contact with their working surfaces with that of the element 3. The current-carrying jaws 9 are urged tight to the element 3 (Fig. 2) with the help of a gear 10, with the jaws 9 being in that case positioned intermediate of two vertical supports 11 with a possiblity of relative displacement in a horizontal plane. Again, as in the first case, any known means - electro-mechanical, hydraulic, pneumatic, etc., may be employed as a drive for the gear 10.
The molding part of the base plate 6 is built up of three sections 12 (Fig. 4). Each section 12 is forced against each other and against the element 3 with the help of a resilient ; clamping member 13 set up between the outer end face surface of the section 12 and a detainer 14 with a possibility of moving ` 30 radially.
Each section 12 of the base plate 6 may be fitted with a heat-removing renewable insertion piece 15 which diminishes .,- ..~"~.
., ,, . .~. ,..
^:: .- : .
.
. .
105~i427 considerably the time for the preparation of the plant when passing over to melting shaped castings with another diameter of the element 3. The height of the renewable insertion piece 15 is at least equal to the radius of the element 3.
If the height of the insertion pieces 15 coming in contact with the element 3 is less than its radius, then the walls of the element 3 will be burnt through at the initial moment of the melting process, and molten slag and metal will flow out. This is atributable to inadequate heat removal from the element 3 which is melted off, with its walls being burnt through below the place of contact of the renewable insertion pieces 15 with the element 3.
To preclude the effluence of molten slag and metal at the beginning of the melting process the joints 16 (Fig. 3) of the sections 12 of the base plate 6 and renewable insertion pieces 15 are made stepped.
Such an embodiment is attributed to the fact that the ^ heating of the element 3 causes its thermal expansion; as a result the detachable sections 12 and renewable insertion pieces 15 of the base plate 6 move apart, forming gaps through which the slag and metal can escape at the first moment of the melting process. The steppéd joints 16 of the sections 12 and renewable insertion pieces 15 of the base plate 6 preclude the effluence '- of both the slag and metal.
The plant for effecting the herein-proposed--method ' functions as follows.
The renewable insertion pieces 15 corresponding to the - size of the element 3 are secured to the detachable sections 12 of the base plate 6. The element 3 is introduced by means for vertical movement of the element 3 such as vertical transfer gear `~ 7 into the melting space of the mold 2 to 0.2-0.6 of the depth of the slag bath 4. Next, the current-carrying jaws 9 are set with ,:
g _ ~ ~.
-:
iO564Z7 the help of the clamping gear lO in their working position so that they are brought in contact with the element 3. A gap between the element 3 and the walls of the renewable insertion pieces 15 is eliminated by means of the resilient clamping member 13. After that the water-cooled mold 2 is mounted on the base plate 6, a slag bath 4 is established and the process of electroslag melting is initiated by melting the consumable electrode l in the slag bath 4 under the effect of an electric current. The heating of the element 3 causes its thermal expansion which is taken up by the resilient clamping member 13, a feature which precludes the warping of the base plate 6.
Considered hereinafter are several examples of the electroslag melting of shaped castings with the concurrent fusing of individual parts by using the above outlined technique.
The influence of the depth of introducing the element 3 into the slag bath 4 and of the ratio between the cross sections of the consumable electrode 1 and element 3 on the quality of fusion was investigated on both a laboratory installation and an industrial one.
The elements to be fused were produced from rolled pro-ducts. The quality of fusion was determined with the aid of macrosections and by non-destructive methods of inspection (gammagraphy and ultrasonic inspection). The results of these investigations are tabulated in Table l.
An analysis of these results reveals that high-quality fusion is ensured when at the beginning of the process the element being fused is introduced into the slag bath to 0.2-0.6 of its depth with the consumable electrode l having a cross section of not less than that of the element 3.
The industrial plant for the electroslag melting of shaped castings by using the above outlined technique was employed for producing an experimental-commercial lot (about 200 pieces) ~ , ,~,;
lOS6427 of cover blanks for fitting bodies of atomic power plants. All of them were checked for quality of the fusion zone and of the base casting metal by the non-destructive methods.
The quality of fusion in all castings was good and defects in the form of porosity, cracks, cold laps, etc. were absent.
The results of investigations of mechanical properties and impact toughness (at room temperature) for two steel grades from different casting zones are given in Table 2. Chemical composition of the steel graaes under investigation is tabulated in Table 3.
An analysis of the above results shows that the state of mechanical properties and impact toughness of the metal in a transition zone and of the cast metal obtained by electroslag melting are isotropic. They are similar to corresponding character-istics of rolled products obtained for specimens cut out along rolled fibers.
Experimental heats treated on the industrial electroslag melting plant have fully demonstrated its reliability, ease of servicing, absence of marked warping of the base plate and of other design elements of the plant.
~' .
~', ' 10564~7 Results of Investigations of Macrosections of Templates of Articles With Fused Elements Produced by Electro-Melting _ _ _ _ Plant type Mold Diameter of Diameter of Depth of Depth of intro-diameter consumable element slagduction of ele-(mm) electrode being fused bath ment into slag (mm) (mm) (mm)bath (mm) .
Experimental Laboratory plant 80 50 50 45 0.0 ' 80 50 50 45 20 lOS64Z7 Tabl e Ratio of cross- Ratio of depth of Quality of fusion sections of con- introducing element sumable electro- to be fused into slag de and element bath to its depth being fus~d 1 0 cold shuts 1 0.06 cold shuts 1 0.13 cold shuts 1 0.16 cold shuts 1.77 0.13 cold shuts 1 0.2 good 1 0.22 good 1 0.33 good : 1 0.44 good 1 0.55 good 1 0.5 good 1 0.33 good 1.21 0.44 good 1.49 0.44 good 1.26 0.33 good 1.77 0.33 good 1 0.33 good 1.23 0.33 good 2.7 0.33 good 1.07 0.33 good :
105~;427 .. . . .. . . .
.. .. ~
: lS0 80 60 70 30 Experimental 80 50 50 45 30 laboratory plant 60 45 40 30 20 ~0 42 45 15 ; 360 200 180 80 10 Industrial _ _ _ __ _ furnace 360 180 180 80 16 .: 360 200 180 80 20 . . , lOS642'7 . _ . . . . . _ . . . ~
1.44 0.33 good 1.77 0.43 gooc~
1 0.43 good . _ _ 1 0.66 Melting process un-1.26 0.66 stable, undercuts 1 0.66 1,3 0.73 0.81 0.33 cold shuts 0.9 0.33 cold shuts 0.79 0.4 cold shuts 0.82 0.4 colcl shuts 0.91 0.33 cold shuts 0.69 0.3 cold shuts 1.23 0.12 cold shuts 1.23 0.17 cold shuts 1.0 0.18 cold shuts 1.0 0.16 cold shuts . . ~
1.0 0.2 good 1.23 0.25 good ~; ~
~ ... . . .
1 2 3 ~ 5 6 7 8 9 :
360 160 180 80 20 1.0 0.25 good :~
520 200 180 90 20 1.23 0.22 good 520 200 200 90 60 1.0 0.66 melting process unstable 360 180 160 80 50 1.26 0.62 undercuts s 360 160 180 80 20 0.79 0.25 cold shuts 360 160 200 80 20 0.64 0.25 cold shuts ~.
360 180 200 80 20 0.81 0.25 cold shuts ' Mechanical Properties and Impact Toughness (Test temperature 20~C) Tensile strength Yield point Materiall Metal being tested _ _ kq/~n _ _k ~mm Metal obtained by elec- 48.5-49.5 24.0-26.0 troslag meltingX) 48.9 25.1 (in different directions) Steel A Transition zone x) 46.0-47.0 23.5-25.0 46.5 24.0 Element being fused 47.0 24.4 (along rolled fibers) 47.0 24.4 :
.. _ _ . .
Steel B Metal obtained by electro- 61.5 22.6 slag melting tin different directions) 52.0 21.5 .
- - . _ Transition zone 61.0 23.8 60.0 23.5 . . . _ . _ _ _ . _ . .
Element being fused 62.5 25.6 (along rolled fibers) 61.0 25.5 . . .
X)Arithmetical mean of 6 tests of metal from 2 heats :
.~.
.
1~5642'7 Table 2 .. . ..
R~lative Relative Impact toughness Elongation % Reduction (of area) kgm/cm2 23 0-35.0 55.5-65.0 14.25-16.5 31.2 62.2 15.7 _ _ _ 31.0 60.6 16i 25~ 18 - 2 32.0 66.0 15.75 33.0 65.6 16.25 14.50 -62.0 78.0 24 66.0 73.0 30 60.0 74.5 29-30X) 29.8 64.0 74 5 52.0 78.5 30 58.0 78.0 30 .. . .
10564*7 Chernical Composition of Material Table 3 Material Car- Sili~ Manga- Tita- Nickel Chro- Sul- Phos-bon cium nese nium mium phur phorus Iron ._ . _ .. --Steel A 0.21 0.31 0.62 - - 0.0~ Q.004 0.016 the balance Steel B 0.08 0.70 1.37 0.48 10.07 17.49 0.003 0.018 the balance -~
_ . _ _ _ . . . . _ _ :;:
,.
-'
The melting process effected in the above manner ensures the uniform fusion of the end face of the fused element introduced into the slag bath and guaranteed fusion of this element to the casting body both along its outline and over its cross section.
According to the invention, the fusion process is pre-~' ferably accomplished in the initial period by using a consumable electrode with a cross section that is at least equal to that ofan element being fused.
In this case the droplets of remelted metal fall onto an already fused surface of the element being fused ensuring thereby the guaranteed quality of fusion.
In accordance with one embodiment, there is provided, in a plant for the electroslag melting of shaped castings by electro-slag remelting of consumable electrodes in a cooled mold mounted on a base plate having an aperture through which an element to be fused in the course of melting is inserted, the improvement being in that the base plate is of a composite construction split along vertical planes, and that the molding part of the base plate comprises at least three sections, resilient members connected to each of said ,sections for forcing the sections against each other and against the element being fused; said mold adapted to accommodate a consumable '~ electrode connected to a power source' means for the vertical ' movement of the element being fused, said means adapted to insert ; the element into the slag bath through the aperture in said base plate; and current-carrying jaws movable in the horizontal plane, said jaws being connected to means adapted to urge them against the element being fused and having electric contact with said power source.
The means for vertical movement being adapted to introduce ~9~ - 3 -- 10564~7 the element being fused into the slag bath to a height ensuring its high-quality fusing to the casting body and facilitating the servicin~ of the plant.
The current-carrying jaws movable in a horizontal plane and fu~nished with the gear for urging them to the element being fused provide a reliable electrical contact and are simple and dependable in operation.
The use of the base plate molding part made up of at least three sections, of which each is coupled with the resilient clamping member, makes it possible to rule out the warping of the base plate due to thermal expansion of the element being fused, to enhance the plant reliability and to extend the service life of the base plate.
According to the present invention, each base plate section can be fitted with a heat-removing renewable insertion piece positioned in the place of contact with the element being fused, with the insertion piece height being at least equal to the radius of the element being fused.
The provision of each base plate section with a heat-removing renewable insertion piece disposed in the place ofcontact with the element being fused enables quick readjustment when passing over from melting a casting with a fused element of one type size to that with another one.
The height of the insertion pieces should be not less than the radius of the element being fused since it ensures it cooling and precludes thereby the burning through of its walls -~ at the initial moment of the melting process, and the runout of molten slag and metal.
According to the invention, the joints of the base plate sections are preferably stepped.
The above embodiment precludes the effluence of the mol-ten slag and metal along the base plate joint at the initial moment ' ,, :`',?`
, .
10564~7 o~ the melting process owing to thermal expansion of the element belng fused, when the base plate sections are displaced relative to one another.
The use of the herein-proposed method and plant for effecting the method materially lowers the production costs in the manufacturing of shaped castings by using the electroslag melting technique and by fusing together individual elements. It also makes it possible to avoid welding. The above outlined procedure and plant are suitable for enlarging castings by using precast or prefabricated (by any other now~existing method) blanks as elements to be fused. Moreover, when using the present invention a considerable saving is provided owing to improved performance characteristics of metal and better quality of castings.
The nature of the invention will be clear from the following detailed description of its particular embodiments to be had in conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic diagram illustrating the electroslag melting process;
Fig. 2 is a schematic diagram of a plant for effecting the proposed method, Fig. 3 is a general axonometric view of a plant for effecting the proposed method of the electroslag melting of shaped castings, and Fig. 4 is a section through IV-IV of Fig. 2.
The herein-proposed method of electroslag melting shaped castings consists essentially of introduclng a consumable electrode 1 (Fig. 1) into the melting space of a mold 2 and mounting an element to be fused 3 in the opening of a base plate 6 coaxially with the consumable electrode 1. Next molten slag is poured into the mold 2 to establish a slag bath 4 of a required height and, by passing an electric current from a power source 5 through an electric circuit cor.sisting of consumable ~'";' .
, -,. : .
electrode 1, slag bath 4 and element to be fused 3, the process of electroslag melting is initiated. In the initial period, the fusion process should be carried out by introducing the element 3 being fused into the slag bath a depth 0.2-0.6 of the depth of the slag bath.
To illustrate the requirements of such an arrangement, the slag bath is considered as a sum of resistances R, such that:
total Rl+R2+R3' where:
Rl is the resistance of poles of the consumable electrode 1 and the element to be fused 3 R2 and R3 are the resistances of poles of the consumable electrode 1 and the base plate 6" (on both sides of consumable electrode 1);
and Rtotal is the total resistance of slag bath ~.
For the sake of simplicity the consumable electrode 1 and element to be fused 3 are assumed to be arranged symmetrically within the melting space of the mold 2. Then R2 may be considered to be equal to R3.
With a constant input electric power fed to the slag bath 4 from the power source 5 a change in spacing ~ between the electrode 1 and the element 3 will cause a redistribution of electric power in the slag bath 4, with the power value changing most intensively in the resistance Rl since the resistances R2 and R3 are almost equal and vary negligibly at a change in the depth of introduction of the element 3 into the slag bath 4. A maximum specific electric power is released along the end face edges of the consumable electrode 1 and element 3. As the spacing ~ be-tween the electrodes decreases, i.e. when the introduction increment ~ of the element 3 becomes larger, the amount of the electric current passing through the element 3 increases, enhancing thereby the rate of fusing of the end face of the element 3 and, hence, s ~ ~ - 6 -....
.
providing better quality of fusion.
Moreover, an increase in the rate of fusion of the end face of the element 3 resulting from a larger introduction incre-merlt a ~ of the element 3 fed into the slag bath 4 is attributable to an increase in the contact surface area of the element 3 and the heated slag bath 4.
Thus, the deeper the element 3 is introduced into the slag bath 4, the better its fusion with the casting body.
However, with a small interelectrode spacing ~ the electroslag process is converted into an arc process, a feature which restricts the introduction increment a 4 of the element 3 to not more than 0.6 of the depth of the slag bath 4.
When the element 3 is introduced into the slag bath 4 to a distance less than 0.2 of its depth, a metal bath established by melting the consumable electrode 1 comes in contact with the element 3 being fused along its still unfused surface, which does not ensure high-quality fusion of this element.
When the electroslag melting process is accomplished in its initial period with a consumable electrode 1 of a cross section that is equal to or exceeds that of the element 3, the drop metal transfer of the consumable electrode 1 occurs in such a way that the droplets of remelted metal fall on an already fused surface of the element 3, forming a common metal bath along the element out-line. This ensures high-quality fusion of the element 3 with the casting body.
The use of a consumable electrode 1 with a cross section smaller than that of the element 3 results in the droplets of electrometal falling on yet unfused surface on the end face of the element which does not provide high-quality fusion.
Considered hereinafter is a plant ensuring the electro-slag melting of shaped castings with the concurrent fusing of individual parts during the melting process.
,~,.:-- -A plant for the electroslag melting of shaped castings comprises a consumable electrode 1 (Figs. 2 and 3) introduced into the melting space of a cooled mold 2, and an element to be fused 3 that is extended into a slag bath 4 from below. The consumable electrode 1 and element 3 are connected to a power source 5.
The mould is mounted on a base plate 6 with an opening ali~ned axially with the consumable electrode 1 and adapted to receive the element 3 which is fed from below into the opening.
The element 3 is set up on the top stage of a vertical transfer gear 7 fixed under the base plate 6 on a supporting plate 8, whereupon said element 3 is introduced with the help of the above gear 7 into the melting space of the mold 2. As for a drive of the gear 7, any known means - electromechanical, hydraulic, pneumatic, manual, etc., can be employed.
An electric current is passed to the element 3 by means of current-carrying jaws 9 movable in a horizontal plane and coming in direct contact with their working surfaces with that of the element 3. The current-carrying jaws 9 are urged tight to the element 3 (Fig. 2) with the help of a gear 10, with the jaws 9 being in that case positioned intermediate of two vertical supports 11 with a possiblity of relative displacement in a horizontal plane. Again, as in the first case, any known means - electro-mechanical, hydraulic, pneumatic, etc., may be employed as a drive for the gear 10.
The molding part of the base plate 6 is built up of three sections 12 (Fig. 4). Each section 12 is forced against each other and against the element 3 with the help of a resilient ; clamping member 13 set up between the outer end face surface of the section 12 and a detainer 14 with a possibility of moving ` 30 radially.
Each section 12 of the base plate 6 may be fitted with a heat-removing renewable insertion piece 15 which diminishes .,- ..~"~.
., ,, . .~. ,..
^:: .- : .
.
. .
105~i427 considerably the time for the preparation of the plant when passing over to melting shaped castings with another diameter of the element 3. The height of the renewable insertion piece 15 is at least equal to the radius of the element 3.
If the height of the insertion pieces 15 coming in contact with the element 3 is less than its radius, then the walls of the element 3 will be burnt through at the initial moment of the melting process, and molten slag and metal will flow out. This is atributable to inadequate heat removal from the element 3 which is melted off, with its walls being burnt through below the place of contact of the renewable insertion pieces 15 with the element 3.
To preclude the effluence of molten slag and metal at the beginning of the melting process the joints 16 (Fig. 3) of the sections 12 of the base plate 6 and renewable insertion pieces 15 are made stepped.
Such an embodiment is attributed to the fact that the ^ heating of the element 3 causes its thermal expansion; as a result the detachable sections 12 and renewable insertion pieces 15 of the base plate 6 move apart, forming gaps through which the slag and metal can escape at the first moment of the melting process. The steppéd joints 16 of the sections 12 and renewable insertion pieces 15 of the base plate 6 preclude the effluence '- of both the slag and metal.
The plant for effecting the herein-proposed--method ' functions as follows.
The renewable insertion pieces 15 corresponding to the - size of the element 3 are secured to the detachable sections 12 of the base plate 6. The element 3 is introduced by means for vertical movement of the element 3 such as vertical transfer gear `~ 7 into the melting space of the mold 2 to 0.2-0.6 of the depth of the slag bath 4. Next, the current-carrying jaws 9 are set with ,:
g _ ~ ~.
-:
iO564Z7 the help of the clamping gear lO in their working position so that they are brought in contact with the element 3. A gap between the element 3 and the walls of the renewable insertion pieces 15 is eliminated by means of the resilient clamping member 13. After that the water-cooled mold 2 is mounted on the base plate 6, a slag bath 4 is established and the process of electroslag melting is initiated by melting the consumable electrode l in the slag bath 4 under the effect of an electric current. The heating of the element 3 causes its thermal expansion which is taken up by the resilient clamping member 13, a feature which precludes the warping of the base plate 6.
Considered hereinafter are several examples of the electroslag melting of shaped castings with the concurrent fusing of individual parts by using the above outlined technique.
The influence of the depth of introducing the element 3 into the slag bath 4 and of the ratio between the cross sections of the consumable electrode 1 and element 3 on the quality of fusion was investigated on both a laboratory installation and an industrial one.
The elements to be fused were produced from rolled pro-ducts. The quality of fusion was determined with the aid of macrosections and by non-destructive methods of inspection (gammagraphy and ultrasonic inspection). The results of these investigations are tabulated in Table l.
An analysis of these results reveals that high-quality fusion is ensured when at the beginning of the process the element being fused is introduced into the slag bath to 0.2-0.6 of its depth with the consumable electrode l having a cross section of not less than that of the element 3.
The industrial plant for the electroslag melting of shaped castings by using the above outlined technique was employed for producing an experimental-commercial lot (about 200 pieces) ~ , ,~,;
lOS6427 of cover blanks for fitting bodies of atomic power plants. All of them were checked for quality of the fusion zone and of the base casting metal by the non-destructive methods.
The quality of fusion in all castings was good and defects in the form of porosity, cracks, cold laps, etc. were absent.
The results of investigations of mechanical properties and impact toughness (at room temperature) for two steel grades from different casting zones are given in Table 2. Chemical composition of the steel graaes under investigation is tabulated in Table 3.
An analysis of the above results shows that the state of mechanical properties and impact toughness of the metal in a transition zone and of the cast metal obtained by electroslag melting are isotropic. They are similar to corresponding character-istics of rolled products obtained for specimens cut out along rolled fibers.
Experimental heats treated on the industrial electroslag melting plant have fully demonstrated its reliability, ease of servicing, absence of marked warping of the base plate and of other design elements of the plant.
~' .
~', ' 10564~7 Results of Investigations of Macrosections of Templates of Articles With Fused Elements Produced by Electro-Melting _ _ _ _ Plant type Mold Diameter of Diameter of Depth of Depth of intro-diameter consumable element slagduction of ele-(mm) electrode being fused bath ment into slag (mm) (mm) (mm)bath (mm) .
Experimental Laboratory plant 80 50 50 45 0.0 ' 80 50 50 45 20 lOS64Z7 Tabl e Ratio of cross- Ratio of depth of Quality of fusion sections of con- introducing element sumable electro- to be fused into slag de and element bath to its depth being fus~d 1 0 cold shuts 1 0.06 cold shuts 1 0.13 cold shuts 1 0.16 cold shuts 1.77 0.13 cold shuts 1 0.2 good 1 0.22 good 1 0.33 good : 1 0.44 good 1 0.55 good 1 0.5 good 1 0.33 good 1.21 0.44 good 1.49 0.44 good 1.26 0.33 good 1.77 0.33 good 1 0.33 good 1.23 0.33 good 2.7 0.33 good 1.07 0.33 good :
105~;427 .. . . .. . . .
.. .. ~
: lS0 80 60 70 30 Experimental 80 50 50 45 30 laboratory plant 60 45 40 30 20 ~0 42 45 15 ; 360 200 180 80 10 Industrial _ _ _ __ _ furnace 360 180 180 80 16 .: 360 200 180 80 20 . . , lOS642'7 . _ . . . . . _ . . . ~
1.44 0.33 good 1.77 0.43 gooc~
1 0.43 good . _ _ 1 0.66 Melting process un-1.26 0.66 stable, undercuts 1 0.66 1,3 0.73 0.81 0.33 cold shuts 0.9 0.33 cold shuts 0.79 0.4 cold shuts 0.82 0.4 colcl shuts 0.91 0.33 cold shuts 0.69 0.3 cold shuts 1.23 0.12 cold shuts 1.23 0.17 cold shuts 1.0 0.18 cold shuts 1.0 0.16 cold shuts . . ~
1.0 0.2 good 1.23 0.25 good ~; ~
~ ... . . .
1 2 3 ~ 5 6 7 8 9 :
360 160 180 80 20 1.0 0.25 good :~
520 200 180 90 20 1.23 0.22 good 520 200 200 90 60 1.0 0.66 melting process unstable 360 180 160 80 50 1.26 0.62 undercuts s 360 160 180 80 20 0.79 0.25 cold shuts 360 160 200 80 20 0.64 0.25 cold shuts ~.
360 180 200 80 20 0.81 0.25 cold shuts ' Mechanical Properties and Impact Toughness (Test temperature 20~C) Tensile strength Yield point Materiall Metal being tested _ _ kq/~n _ _k ~mm Metal obtained by elec- 48.5-49.5 24.0-26.0 troslag meltingX) 48.9 25.1 (in different directions) Steel A Transition zone x) 46.0-47.0 23.5-25.0 46.5 24.0 Element being fused 47.0 24.4 (along rolled fibers) 47.0 24.4 :
.. _ _ . .
Steel B Metal obtained by electro- 61.5 22.6 slag melting tin different directions) 52.0 21.5 .
- - . _ Transition zone 61.0 23.8 60.0 23.5 . . . _ . _ _ _ . _ . .
Element being fused 62.5 25.6 (along rolled fibers) 61.0 25.5 . . .
X)Arithmetical mean of 6 tests of metal from 2 heats :
.~.
.
1~5642'7 Table 2 .. . ..
R~lative Relative Impact toughness Elongation % Reduction (of area) kgm/cm2 23 0-35.0 55.5-65.0 14.25-16.5 31.2 62.2 15.7 _ _ _ 31.0 60.6 16i 25~ 18 - 2 32.0 66.0 15.75 33.0 65.6 16.25 14.50 -62.0 78.0 24 66.0 73.0 30 60.0 74.5 29-30X) 29.8 64.0 74 5 52.0 78.5 30 58.0 78.0 30 .. . .
10564*7 Chernical Composition of Material Table 3 Material Car- Sili~ Manga- Tita- Nickel Chro- Sul- Phos-bon cium nese nium mium phur phorus Iron ._ . _ .. --Steel A 0.21 0.31 0.62 - - 0.0~ Q.004 0.016 the balance Steel B 0.08 0.70 1.37 0.48 10.07 17.49 0.003 0.018 the balance -~
_ . _ _ _ . . . . _ _ :;:
,.
-'
Claims (5)
1. In a plant for the electroslag melting of shaped castings by electroslag remelting of consumable electrodes in a cooled mold mounted on a base plate having an aperture through which an element to be fused in the course of melting is inserted, the improvement being in that the base plate is of a composite construction split along vertical planes, and that the molding part of the base plate comprises at least three sections, resilient members connected to each of said sections for forcing the sections against each other and against the element being fused, said mold adapted to accommodate a consumable electrode connected to a power source means for the vertical movement of the element being fused; said means adapted to insert the element into the slag bath through the aperture in said base plate, and current-carrying jaws movable in the horizontal plane, said jaws being connected to means adapted to urge them against the element being fused and having electric contact with said power source.
2. The plant of claim 1, wherein each of the base plate sections is provided with a heat-removing renewable insertion piece adapted to contact the element to be fused, the height of the insertion piece being at least equal to the radius of the element to be fused.
3. The plant of claim 2, wherein the contact surfaces be-tween the base plate sections and the renewable insertion pieces are stepped.
4. In a method of electroslag melting shaped castings by remelting a consumable electrode in a slag bath with the con-current fusing of an element, the improvement comprising: intro-ducing the element being fused into the slag bath to 0.2-0.6 of the depth of the slag bath at the initial stage of the fusion process.
5. The method of claim 4, wherein the consumable electrode has a cross section that is at least equal to that of the element being fused.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SU7402019186A SU487548A1 (en) | 1974-04-25 | 1974-04-25 | Method of electroslag melting of mould castings |
| SU7402023693A SU487545A1 (en) | 1974-05-15 | 1974-05-15 | Device for electroslag melting |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1056427A true CA1056427A (en) | 1979-06-12 |
Family
ID=26665513
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA224,980A Expired CA1056427A (en) | 1974-04-25 | 1975-04-18 | Electroslag melting of shaped castings |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS51129803A (en) |
| CA (1) | CA1056427A (en) |
| CS (1) | CS196545B1 (en) |
| DD (1) | DD117377A1 (en) |
| DE (1) | DE2559565C3 (en) |
| FR (1) | FR2268588A1 (en) |
| SE (1) | SE412539B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114082923A (en) * | 2021-09-28 | 2022-02-25 | 材谷金带(佛山)金属复合材料有限公司 | 1050 aluminum/08 AL steel composite plate heat treatment method |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3630105A (en) * | 1970-05-15 | 1971-12-28 | Amp Inc | Wire-stripping machine |
| NL174659C (en) * | 1972-03-27 | 1984-07-16 | Pennwalt Corp | METHOD FOR ODORIZING LIQUEFIED, FLAMMABLE HYDROCARBON GAS. |
| JPS5820958B2 (en) * | 1972-05-08 | 1983-04-26 | 帝人株式会社 | Pyridine Rui no Seizouhou |
-
1975
- 1975-04-18 CA CA224,980A patent/CA1056427A/en not_active Expired
- 1975-04-22 CS CS279975A patent/CS196545B1/en unknown
- 1975-04-23 FR FR7512643A patent/FR2268588A1/en active Granted
- 1975-04-23 DD DD18564775A patent/DD117377A1/xx unknown
- 1975-04-24 SE SE7504785A patent/SE412539B/en not_active IP Right Cessation
- 1975-04-25 JP JP50050604A patent/JPS51129803A/en active Pending
- 1975-04-25 DE DE19752559565 patent/DE2559565C3/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CS196545B1 (en) | 1980-03-31 |
| FR2268588B1 (en) | 1977-04-15 |
| SE7504785L (en) | 1975-10-27 |
| DD117377A1 (en) | 1976-01-12 |
| JPS51129803A (en) | 1976-11-11 |
| DE2559565A1 (en) | 1977-04-14 |
| DE2518517A1 (en) | 1975-10-30 |
| DE2559565C3 (en) | 1978-12-21 |
| DE2518517B2 (en) | 1977-04-28 |
| SE412539B (en) | 1980-03-10 |
| FR2268588A1 (en) | 1975-11-21 |
| DE2559565B2 (en) | 1978-04-27 |
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