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1. What are two ways of doing forge welding?
2. Try to describe these ways with your own words.
3. What are the most applications of forge welding?
4. Who published a book about forge welding in 1540?
5. What did this book contain?
6. What is the role of temperature in forge welding?
7. What is the difference in melting temperature in creating of steel-welds and iron ones?
Exercise 3. Translate the following sentences into Russian
1. This method attempts to fasten together two or more metal components through a process of heating, hammering and striking.
2. In this process, steels are repetitively drawn out, folded back and welded upon itself.
3. One of the most popular applications of forge welding is the manufacturing of pattern-welded blades.
4. This is being done between dissimilar materials, allowing you to make weld that is stronger than individual metals.
Exercise 4. Give the verbs the following nouns derived from:
application, heating, hammering, striking, manufacturing, industrialization, welding, production, forging, oxidation, preparation, bonding, faying
Exercise 5. Find the equivalents:
1. due to
2. by
3. as
4. both...and
5. without
6. because
Exercise 6. Use the following words and phrases in sentences of your own:
electrode, to weld, welding methods, oxidation, metal components
Find out more about forge welding
Text 2. Forge welding (Part 2)
Forge Welding - Forge welding is the oldest known welding process which has been practiced for centuries. The process is still used although its application is restricted because of the certain difficulties associated with it.
Metals Which can be Forge Welded
Wrought iron and low carbon steels (with C content less than 0.2%) can be satisfactory forge welded. Forge welding can be carried out with metal thicknesses up to about 30 mm.
Fuel and Furnaces Required
Coal, coke, charcoal, gas and oil can be used in furnaces required to heat objects to the plastic state. Heating must be uniform and neither too much nor too little. Too much heat may burn the metal and produce a brittle weld. Too little heat will prevent the metal from being plastic and thus result, in a weak inadequate weld.
Surface Preparation
Surfaces of the metal pieces to be forge welded are prepared by upsetting the pieces at the ends. Various edge preparations required to be carried out before forge welding.
Procedure for Forge Welding
The parts to be forge welded are given an edge (or joint) preparation as explained above. Then, the parts are heated to over l000°C until they are plastic. In this condition, the parts are placed on the anvil end to end and are hammered together, either using a power hammer or manually, until they form a solid structure of metal.
In forge welding operation, a very important requirement is that during heating the absorption of sulphur from the coke of the fire and scaling of the pieces (to be welded) should be prevented or that if scale is formed, the hammering should be done in such a way as to squeeze this out of the joint and permit metal to metal contact. Besides being united by blows from a hammer, the workpieces may also be welded by being rolled, drawn or squeezed together.
Advantages and Disadvantages and Applications of Forge Welding - If made correctly, a forge welded joint has every quality of the original metal and is as good in strength as an arc or oxyacetylene welded joint.
Disadvantages
(i) Forge welding requires considerable skill on the part of the operator.
(ii) It is restricted to wrought iron and mild steel.
(iii) It is usually limited to the joining together of pieces of solid steel stock.
(vi) It is a slow process as compared to arc and gas welding.
(v) There is the danger of sulphur pickup by the metal from the coke of the furnace.
Applications
(i) Forge welding finds use in blacksmith shops, rail road shops and repair shops of general character.
(ii) (ii) It is also used for making pipes from plates by rolling the plate to cylindrical form and making the longitudinal junction by forge welding. Strip/plate is pulled through dies to form a rolled cylinder, the long edges being butted together in the dies at the high temperature required to form a forge weld
(iii) Types of Forge Welding – 1. Fire welding in which pieces to be joined are heated in the fire by the blacksmith. He withdraws them at the appropriate time and joins them by hammer blows. 2. Water gas welding which finds application in the manufacture of pipes, containers, etc. Edges of the plate (to be converted into a pipe) are heated by water gas flame. (consisting essentially of hydrogen, carbon monoxide and nitrogen) and as they attain the appropriate temperature, they are welded together under the hammer or by means of pressure rollers.
Flux Requirements The flux
(i) gives protection (to metal pieces) from oxidation.
(ii) combines with the oxides to form a fluid slag which is readily squeezed out of the joint thereby preventing the scale from being trapped at any point between the joint surfaces. This produces a sound weld.
(iii) used to dissolve oxides, forms a protective coating and shield over the heated area of the metal and prevents further oxidation and burning of metal. Borax in combination with salammoniac is the most commonly used flux for forge welding steel.
VOCABULARY:
| Coal - уголь weld - шов edge - край, кромка anvil - наковальня considerable - значительный | Shop - цех roll - прокатывать draw - тянуть, вытягивать advantage - преимущество manufacture - производство |
Дата: 2019-07-24, просмотров: 290.