Think of your own sentences according to this pattern.

Task 7.

Fill in the gaps with the words given bellow. Translate the sentences.

advantages, electricity, processes, melting,

wasteless technology, electroslag casting

1. _____ covers remelting, casting, welding of large-section billets and hard surfacing.

2. Melting _____ in electric arc furnaces, coreless induction furnaces and cored induction furnaces are of great interest.

3. The technological process of ESC represents an example of _____.

4. Electric furnaces offer a number of _____.

5. Electro-metallurgy deals with the use of _____ for metal smelting or refining, for alloy manufacturing and for some casting processes.

6. Arc furnaces are used for _____ high-grade irons.

Task 8.	Make the word combinations matching the words from column A with the words from column B and translate them.
	A	B
	1. foundry 2. electro-slag 3. effective 4. melting 5. duplex 6. conventional 7. technological	a) process b) loss c) casting d) practice e) field f) use g) rate

Task 9.	Fill in the table with the missing information.
Furnace or process	Use
Electric arc furnace
	is used for: 1) melting iron from a solid metal charge; 2) preheating the iron and refining it to the analysis
Electroslag casting

Task 10.

Answer the following questions:

1. What does electrometallurgy deal with?

2. What melting processes of electro-metallurgy are of great interest?

3. Do electric arc furnaces have any advantages? What are they?

4. Can you say a few words about coreless induction furnaces?

5. Where do cored induction furnaces find effective uses?

Task 11.	Write about the advantages of electroslag casting as compared with conventional casting.
Task 12.	Translate the following questions into English and answer them:

1. Що включає процес електрошлакового лиття?

2. На чому базується електрошлакове лиття?

3. Чим плавиться споживаний стальний електрод?

4. Від чого залежить споживана потужність у процесі ЕШЛ?

5. Які переваги електрошлакового лиття ви знаєте?

6. Де постійно розробляються нові методи ЕШЛ?

UNIT 7

EQUIPMENT FOR ELECTROSLAG CASTING

The standard equipment used for the ESC process (the unit for feeding consumable electrodes into the mould cavity and controlling their melting process in the sand mould, the mould and electric power source) and the auxiliary equipment (a unit for melting and pouring the slag and a stand for assembling and welding of electrodes) are practically the same as for the ESR method.

Until recently, for producing cast products of any shape the water-cooled casting moulds were created in such a way that to provide the successive casting formation by gradual filling these moulds with metal during the electrode remelting. Such an approach to the ESC problem allowed to use the commercial ESR units. In the ESC process, however, the casting mould, unlike the ESR, is the most important part of the unit. It is of a much more complicated shape than the ESR unit mould, the shape being determined by configuration of the billet melted.

Obviously, the most complex-shaped castings are obtainable by making use of the moulds which are stationary with respect to the castings. Such moulds may be subdivided into two types, the first comprising the moulds in which the casting is made as a whole, while in the second the linking part of the future article is cast first and the parts to be linked, already made by the ESC or another method and inserted into relevant holes of the mould, are fused up to the said linking part.

In the ESR the removal of round-, square- or rectangular-section ingots is no problem at all, the mould side wall having usually no joints in this case. When melting shaped castings having lugs and recesses, the mould should necessarily have joints allowing to break it into more simple elements. These joints make it possible to liberate the casting from individual parts of the mould.

With the casting configuration getting more intricate, the number of joints grows too. In their turn, the detachable moulds may also be subdivided into two types. Those which are dismantled after a complete cooling down of the casting belong to the first type. Should, however, some parts of the mould happen to get pinched between the casting projections getting shrinked when cooled down, provision is made for the casting portion already solidified to be stripped from the relevant mould parts. Thus, a necessity arises to strip the casting consequently part by part in the process of its making. Such casting moulds belong to the second type.

Until now we discussed the moulds in which both the fusion of electrodes and solidification of the molten metal casting run in parallel. The ESC mould with the metal pouring comprises at least two parts, stationary part where the casting is formed, and a movable one, or a melting unit, where the molten metal is accumulated. The mould cavity is confined by three water-cooled walls. Along the fourth side, which is open, the melting unit is movably secured, the latter presenting a water-cooled metal box structure with the space for fusing consumable electrodes confined from three sides by relatively low-height walls. The fourth low-height wall of the melting unit has a threshold for metal discharge and is intended to shape the surface of casting made in the stationary mould. The mould itself serves as a fourth wall. Depending on the complexity of the casting, the mould may have joints to facilitate "stripping" of the ready-made casting and is also provided with several cavities which are metal-filled in from a single movable unit.

Both in the ESC and ESR technologies, the casting mould is a water-cooled crystallizer. For the ESR typical is an intensive cooling down of the whole mould, this having little effect upon the quality of the outer surface of a round or square-shaped ingot. For the ESC a uniform dissipation of heat from all portions of the casting mould with the heat supply to the parts remote from electrode fusion area being non-uniform, leads to deterioration of the casting surface quality.

Task 1.

Pronounce correctly the following words and word combinations from the text “Equipment for ESC”:

the detachable moulds, rectangular-section ingots, a uniform dissipation, the electrode remelting, the gradual filling, the initial stage, to dismantle, necessity, consequently, stationary parts, relatively, a threshold, the surface of casting, to facilitate.

Task 2. Translate the following words and word combinations into English:

подача витратних електродів у ливарну форму, контролювати плавильний процес, джерело електроенергії, допоміжне обладнання, стенд для установки та зварювання електродів, вироби будь-якої форми, створювати ливарні форми, поступове заповнення, переплав електродів, виливок, користуватись, нерухомий, частина, яка об’єднує, виріб, вставити у відповідні отвори, з’єднувати за допомогою плавлення, видалення злитку, прямокутний, кругле січення, виступи і заглибини, знімати (демонтувати), затискатися, фасонувати.

Task 3.

Give the Ukrainian equivalents to the following words and word combinations:

the initial stage, to provide, the cast products, the standard equipment, an approach to a problem, to employ, complicated shape, the most complex-shaped castings, to obtain, to make use, square section, joints, to break the mould into elements, to dismantle, the complete cooling, to get pinched, the casting projections, the solidification of the molten metal, the metal pouring, to accumulate the molten metal, to confine, an uniform dissipation.

Task 4.

Translate the following sentences into English using given words and word combinations in italics:

lugs and recesses, joint, to liberate, the detachable moulds,a complete cooling, to dismantle, to get pinched, the casting projections,the cooling process, to confine, water-cooled walls.

1. Якщо у формі виливок має виступи і заглибини, ливарна форма повинна мати спеціальний пристрій для рознімання. За допомогою такого пристрою для рознімання інженер вивільняє окремі частини виливка з ливарної форми.

2. Знімні ливарні форми поділяють на два види. Знімні ливарні форми, які видаляють після повного охолодження, відносять до першого типу.

3. Окремі частини ливарної форми можуть затискатися між випуклими частинами виливка при усадці в процесі охолодження.

4. Порожнина ливарної форми обмежована трьома стінами з водним охолодженням.

Task 5.

Answer the following questions:

1. Can you name the components of the standard equipment and the auxiliary equipment used for the ESC process?

2. What is the most important part of the unit in the ESC process unlike the ESR process?

3. Being the important part of the ESC process, the casting mould used in the ESC process is much simpler in its configuration, isn’t it?

4. To obtain the most complex-shaped castings, an engineer makes use of the moulds which are stationary with respect to the castings. Such moulds are subdivided into two types. Can you name them?

5. How many types of the detachable moulds do you know from the text? Describe them.

6. How many parts does the electroslag casting mould comprise?

7. Give a detailed picture of the melting unit of the ESC process. Where is a threshold for metal discharge situated? What is a purpose of this threshold?

UNIT 8

MATERIALS USED IN ELEGTROSLAG CASTING

To run the ESC process provision is to be made for consumable electrodes, flux or its components to prepare liquid slag; electric power to generate heat in slag pool; water to cool casting mould, in some cases dry air, inert or other gas suitable for blasting slag and metal pool; compressed air or working fluid to control the operation of pneumatic or hydraulic equipment.

The methods of manufacturing consumable electrodes include continuous and, centrifugal casting, casting into graphite or iron moulds and also making them of metallurgical rolled steel. The cast electrodes, even though affected by porosity and blisters, are usually not discarded since such defects never exert appreciable influence on the remelted metal quality. Neither is a failure of some melts to fall within the acceptable range of chemical composition values the reason for the electrodes to be discarded. By an adequate set-combination of electrodes of different melts, it is possible not only to obtain the castings whose chemical composition meets the technical requirements, but also to make closer the range of chemical composition values for a given grade of steel in its basic constituents and to ensure the highest possible and most stable properties of the casting metal. The surface of electrodes may be subjected to special pre-treatment like shot-blasting or machining in order to remove scale, rust, burning-on etc.

The ESC method is suitable for producing castings practically of all kinds and categories of material (steel, alloys, non-ferrous metals, nodular cast iron, high-strength cast iron etc.). Therefore, in each particular case of producing castings from a certain material, use should be made of proper chemically composed billets as consumable electrodes.

In the ESC process flux serves as a medium to generate the heat required for melting consumable electrodes and also as a basic means to maintain and control chemical composition of the remelted metal. The degree of refining, removal of impurities from the metal while preserving the alloying constituents therein, depend on the molten slag activity.

The melting temperature of flux should be slightly lower than that of the metal itself. Furthermore, the molten flux should have a low viscosity. In the ESC process these two factors create favourable conditions for a thin slag crust formation thus improving the cooling of castings and making their surface better. In the electroslag process oxyfluoride slag systems have the most multipurpose application.

The minimum oxidation capacity is inherent in the slags which contain no oxides. The higher the basicity of a slag (basic-to-acid oxide ratio), the higher its desulphurization ability is. A low or moderate content of alumina in a flux lowers the rate of metal melting thus reducing the possibility of axial porosity and shrinkage cavities to be formed in the casting. Reduction of lime content in the flux weakens its hydration susceptibility thus reducing its chance to cause porosity and shrinkage cavities in the casting. Hydrogen percentage in the metal largely depends on the flux composition. A flux with low lime content is less sensitive to hydrogen embrittlement than a flux rich in lime. In this respect the aluminous flux AHO-6 is considered to have high protective properties.

Prior to be used, the flux is prefused in a graphite crucible by a graphite electrode, due to which a proper refining of slag from moisture, silica, iron oxides, sulphur and lead is achieved. To start the ESC process the liquid slag is poured into the casting mould by a syphon method (through the bottom) or through its top. The consumption of cooling water depends in each particular case on the size of the casting to be produced and the cooling water temperature at the mould inlet.

Task 1. Find in the text English equivalents to the following words and word combinations:

витратний електрод, флюс, шлакова ванна, охолоджувати, інертний газ, продувка, управляти дією пневматичного чи гідравлічного обладнання, методи виробництва, центробіжне лиття, сталепрокат, впливати, міхур (здуття), помітний вплив, якість металу, розплав, відбраковуватись, відповідати вимогам, сорт сталі, основні складові, поверхня, шрото-струменевий, зчищати накип, утворення пригару, чавун з кулькоподібним графітом, високоміцний, заготівка, середовище, основні засоби, ступінь очищення, видалення домішок, низька в’язкість, утворення кірки, відношення, помірний вміст, усадка, вміст вапна, залежати від, склад флюсу, крихкість, захисні властивості, тигель, вологість, кремнезем, оксид заліза, свинець, споживання, вхідний отвір ливарної форми.

Task 2. Give Ukrainian equivalents to the following words and word combinations:

to run the process, liquid slag, to generate heat, casting mould, dry air, suitable, compressed air, fluid, casting into graphite or iron moulds, porosity, failure, chemical composition, value, to obtain the castings, to ensure, the highest possible and most stable properties, be subjected to, special pre-treatment, machining, rust, non-ferrous metals, high-strength cast iron, to generate, to maintain and control chemical composition, to preserve, melting temperature, favourable conditions, multipurpose application, oxidation capacity, to contain, ability, to lower, rate, cavities, to weaken, susceptibility, to cause porosity, percentage, less sensitive, high protective properties, prior to, prefuse, graphite electrode, due to, proper, iron oxides, sulphur, to achieve, to pour, bottom, top.

Task 3. Translate into English the following word combinations. Use the words given below. (N+N constructions)

ванна шлаку	ванна металу
металева ливарна форма (кокіль)	якість металу
активність шлаку	утворення кірки
здатність до окислення	здатність десульфуризації
усадочні порожнини	вміст вапна
відсотковий вміст водню	склад флюсу
графітовий тигель	рідкий шлак
температура води	вхідний отвір ливарної форми.

capacity crust slag metal iron temperature cavities lime mould metal quality mould slag composition inlet formation oxidation desulphurization pool shrinkage activity content percentage flux graphite ability pool crucible liquid water hydrogen

Task 4.	Fill in the correct word from the list below and translate the word combinations. Some words may be used more than once.
a) melting, b) flux, c) equipment, d) electrodes, e) manufacturing, f) slag, g) casting, h) axial porosity, i) steel, j) castings, k) impurities, l) refining

1. refining of …, 2. possibility of …, 3. the cooling of …, 4. size of the …, 5. melting temperature of …, 6. the operation of …, 7. surface of …, 8. degree of …, 9. methods of …, 10. rate of …, 11. removal of …, 12. grade of …

Task 5.

Match the following words. Some words may be used more than once. Translate the word combinations into Ukrainian.

1. low 2. moderate 3. casting 4. consumable 5. main 6. stable 7. special 8. protective 9. favourable 10. chemical 11. appreciable 12. melting 13. technical 14. proper

a) mould b) means c) conditions d) influence e) viscosity f) refining g) temperature h) pre-treatment i) electrode j) metal k) composition l) content m) requirements n) properties

Task 6. Try to explain the following notions:

multipurpose application, consumable electrode, shrinkage, porosity, component.

Task 7. Answer the following questions:

1. What provision is to be made to run the ESC?

2. Name the methods of manufacturing consumable electrodes.

3. What castings can be produced by ESC?

4. Is the molten slag activity important for the refining, removal of impurities from the metal?

5. What slag has the most multipurpose application in electroslag process?

6. In what way does the content of alumina influence the quality of casting?

7. What does the hydrogen percentage of the metal depend on?

8. How can the refining of slag from moisture and silica be achieved?

9. How is the ESC process started?

10. What does the consumption of cooling water depend on?

Дата добавления: 2015-11-14