The most important metal in industr

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.

Результаты (английский) 3:

工业中最重要的金属是铁及其合金钢。钢是铁和碳的合金。它的强大和僵硬，但腐蚀容易通过生锈，虽然不锈钢及其他特殊钢抗腐蚀。钢中的碳量对其性能有很大的影响。低碳含量的钢（低碳）是相当韧性的，并用于板铁，电线和管道的制造中。含有从0.2到0.4的碳的中碳钢是更强硬，更强大，被用来作为结构钢。适用于锻造和焊接的中碳钢。高碳钢含有从0.4到1.5的碳，是硬而脆的，用于切割工具，外科手术器械，剃刀刀片和弹簧。工具钢，也被称为银钢，含有约1个碳，并通过淬火和回火加强和增韧。其他元素的加入会影响钢的性能。锰提供了额外的强度和韧性。含有百分之4的硅钢用于变压器铁芯或电磁铁具有颗粒大的像小磁铁。铬的加入增加了额外的强度和耐腐蚀性，所以我们可以得到防锈钢。在碳或氮的丰富的材料的存在下加热被用来形成一个坚硬的表面上的钢（表面硬化）。高速钢，这是非常重要的机床，含有铬和钨加少量的钒，钼和其他金属。