С, нужно ответить на вопросы используя текст text в: «steel» the most important metal in industry is iron and its alloy — steel. steel is an alloy of iron and carbon. it is strong and stiff, but corrodes easily through rusting, although stainless and other special steels resist corrosion. the amount of carbon in a steel influences its properties considerably. steels of low carbon content (mild steels) are quite ductile and are used in the manufacture of sheet iron, wire, and pipes. medium-carbon steels containing from 0.2 to 0.4 per cent carbon are tougher and stronger and are used as structural steels. both mild and medium-carbon steels are suitable for forging and welding. high-carbon steels contain from 0.4 to 1.5 per cent carbon, are hard and brittle and are used in cutting tools, surgical instruments, razor blades and springs. tool steel, also called silver steel, contains about 1 per cent carbon and is strengthened and toughened by quenching and tempering. the inclusion of other elements affects the properties of the steel. manganese gives extra strength and toughness. steel containing 4 per cent silicon is used for transformer cores or electromagnets because it has large grains acting like small magnets. the addition of chromium gives extra strength and corrosion resistance, so we can get rust-proof steels. heating in the presence of carbon or nitrogen-rich materials is used to form a hard surface on steel (case-hardening). high-speed steels, which are extremely important in machine-tools, contain chromium and tungsten plus smaller amounts of vanadium, molybdenum and other metals. general understanding: 1. what is steel? 2. what are the main properties of steel? 3. what are the drawbacks of steel? 4. what kinds of steel do you know? where are they used? 5. what gives the addition of manganese, silicon and chromium to steel? 6. what can be made of mild steels (medium-carbon steels, high-carbon steels)? 7. what kind of steels can be forged and welded? 8. how can we get rust-proof (stainless) steel? 9. what is used to form a hard surface on steel? 10. what are high-speed steels alloyed with?
1. What is steel?
Steel is an alloy of iron and carbon.
2. What are the main properties of steel?
Steel is strong and stiff.
3. What are the drawbacks of steel?
Steel corrodes easily through rusting.
4. What kinds of steel do you know?
We know stainless steel, low-carbon steels, medium-carbon steels, high-carbon steels and tool steel (silver steel).
Where are they used?
They are used in manufacturing parts and machines for various industries.
5. What gives the addition of manganese, silicon and chromium to steel?
Manganese gives extra strength and toughness. Steel containing 4 per cent silicon is used for transformer cores or electromagnets. The addition of chromium gives extra strength and corrosion resistance.
6. What can be made of mild steels (medium-carbon steels, high-carbon steels)?
Low carbon steels are used in the manufacture of sheet iron, wire, and pipes. Medium-carbon steels are used as structural steels. Both mild and medium-carbon steels are suitable for forging and welding. High-carbon steels are used in cutting tools, surgical instruments, razor blades and springs.
7. What kind of steels can be forged and welded?
Mild and medium-carbon steels are suitable for forging and welding.
8. How can we get rust-proof (stainless) steel?
We can get rust-proof steels by adding chromium to steel.
9. What is used to form a hard surface on steel?
Heating in the presence of carbon or nitrogen-rich materials is used to form a hard surface on steel.
10. What are high-speed steels alloyed with?
High-speed steels are alloyed with chromium and tungsten plus smaller amounts of vanadium, molybdenum and other metals.