1. Translate into English the following words and word combinations:

изучение машиностроительных процессов

подходящие материалы

деталь машины

зависит от химического состава материала

самый распространенный в мире металл

за которым следует…

сплав железа и углерода

чугун – термин, применяемый к…

серый чугун

сталь – это железосодержащий металл

сопротивление коррозии

кованое железо

Text 6. Non-ferrous metals and non-metallic materials

Alloy steels are those in which some alloying element in addition to the carbon is present in some appreciable quantity. The principal alloying elements used in steel are nickel, chromium, vanadium, molybdenum, manganese, and to lesser extent, copper, tungsten, cobalt, beryllium and boron.

Among non-ferrous metals copper is the most important. Because of its high electric conductivity about 60% of all the copper produced is used in electrical work. Three chief groups of copper alloys used in machine design are brasses (copper-zinc alloys), bronzes (copper-tin alloys), and nickel-copper alloys.

Aluminium is one of the lightest metals used for machine construction. It is commonly used alloyed with copper, silicon or magnesium, the world's lightest structural metal.

Intensive chemical research has created a large number of nonnietallic synthetic materials grouped under the general term of plastics, e.g. bakelite, plexiglass, textile fibres, synthetic rubber and several protective coatings.

Heat-treatment is the process of controlled heating and cooling of metals to change their structural arrangement and to ensure certain desirable properties.

Annealing consists of heating the metal to a temperature slightly above the critical temperature and then cooling slowly to produce an even grain structure, reduce the hardness, and increase the ductility.

Normalizing is a form of annealing in which the material is cooled in the air.

Quenching or rapid cooling from above the critical temperature by immersion in cold water or some other cooling medium, is a hardening treatment.

Tempering consists of reheating the quenched metal to restore ductility to some extent and reduce the briltleness.

Text 7. Copper

Copper was used in prehistoric limes for making weapons and tools and later was alloyed with tin to form bronze, which was the most important metal of the Greeks and Romans. It was replaced for these purposes by iron and steel. Various grades of copper are used for engineering purposes. The great development of the electric industries has resulted in such extensive uses of the metal that it now ranks next to iron in importance.

The copper alloys are more widely employed. The alloying of copper with other elements increases the strength of the metal in some cases and improves the anticorrosive and antifriction properties in others. Copper alloys comprise two main groups — brasses and bronzes. Alloys of copper and zinc are called brasses. Alloys of copper with a number of elements including tin, aluminium, manganese, iron and beryllium are called bronzes.