Exercise 14. Find out some other biographies using Internet (Paton, Petrov, Kjelberge, Lodygin and tell about one of these famous scientists).

Exercise 15. Write an abstract and a summary for the text HISTORY OF WELDING - IN THE BEGINNING.

Exercise 16. Make an oral presentation on topic: Weldability of Metals. Use Internet and library recourses.

Unit 3

Basic Types of Welding.

Basic Level:

Exercise 1. Answer the following questions. Use the background knowledge.

1. What do you know about forge welding?
2. Can you describe this process?
3. Call approximately: when was forge welding begun to use?
4.  What could you say about term: “fire welding”
5. What applications of forge welding do you know?

TEXT 1. Forge welding (Part 1)

Forge welding is said to be the oldest welding technique ever used by early blacksmiths, dating back to the Iron Age when ancient Egyptians and people from Eastern Mediterranean began to refine the craft of welding iron metals together.

Also known as “fire welding,” this method attempts to fasten together two or more metal components through a process of heating, hammering and striking. It is also the “simplest” solid-phase bonding method that utilizes heat and pressure to create the weld.

Being able to join a host of similar and dissimilar materials, forge welding is very versatile. Although this technology has been around for centuries, it was not until the first half of the second millennium A.D when forge welding was formalized upon the publication of Vannoccio Biringuccio’s book entitled “De la pirotechnia” in 1540. This book contains descriptions of early forge welding techniques. However, due to the advent of industrialization which gave birth to more sophisticated welding methods, this technique has been replaced.

There are two ways of doing forge welding. One way is through solid-state diffusion which is applied to bond two similar metal components. This results in a weld that contains only the welded metals with no bridging materials or fillers. This application requires tedious surface preparation because too much oxidation of the faying surfaces would lessen the joint strength significantly. Another method of forge welding is by the formation of a lower melting temperature eutectic. This is being done between dissimilar materials, allowing you to make weld that is stronger than individual metals.

One of the most popular applications of forge welding is the manufacturing of pattern-welded blades. In this process, steels are repetitively drawn out, folded back and welded upon it. Another lesser known application is the production of shotgun barrels. In this method, metal wire is coiled onto a mandrel before forging it into a barrel.

For a forge welding job to be successful, 50-90% of the melting temperature is recommended. Take note that steel welds at a much lower temperature than iron. Utmost care must be taken to prevent overheating the metals.

Vocabulary: