Modern technical civilization is hard to imagine without steel. Various grades of this material are used almost everywhere. Both ordinary household items and complex appliances are made from it. But ideally, steel is an alloy of iron and carbon, however, like cast iron. And only the percentage of C2 distinguishes them. That is, if the alloy has less than 2.14% carbon, then it is steel, and if it is more, then it is already cast iron. But in fact, each steel contains various impurities, such as silicon, phosphorus, sulfur and manganese. And metallurgists, adding to it elements such as chromium, magnesium, molybdenum, nickel, tungsten and vanadium, changing the percentage of alloying elements and carbon, produce various grades of this alloy, which differ significantly in quality.
In this regard, they are alloyed and carbon. And the quality of carbon steel (consisting only of iron and carbon) depends on the amount of C2 in it. That is, if such an alloy contains up to 0.3% carbon, then it is called soft or technical iron. And in solid steel, the percentage of this element is in the range of 0.3-2.14%. But each of the grades of this alloy has its own purpose. So, for example, technical iron has high ductility, does not harden, is easily forged, welded and rolled both in cold and in hot condition. Therefore, mild steel is a relatively cheap material for the manufacture of various non-load bearing parts.
Hard grades of this alloy are used for other purposes. So, for example, many tech-savvy people know what GOST steel 45 is. That is, this alloy contains 0.45% carbon. This steel can already be fired, improved and machined. After improvement, such details as connecting rods, crankshafts, flywheels, ring gears, axles, bolts and others are made of it. It also has the ability to surface harden with HDTV. And this makes it possible to make gears, long and running shafts from it, that is, parts that must have high surface hardness and increased wear resistance with low deformation.
In engineering, alloyed chrome steel is widely used. This is already a material for the manufacture of parts of increased strength, which work under light loads. Such an alloy is difficult to weld; it requires heating and subsequent heat treatment. So, for example, shafts, axles, rods, plungers, pinion shafts, spindles and rings are made of 40X steel . It is suitable for the manufacture of cam and crankshafts, racks, mandrels, bushings, gears and other precision parts.
Corrosion-resistant or stainless steel is also widely used . These are such brands as 40 X 13, 30 X 13, 12 X 13 and several others. These alloys are the material for the manufacture of measuring and cutting tools, household items, carburetor needles, springs and other similar parts that work in corrosive environments and at temperatures up to 450 degrees. And such steel as 15 is called ball-bearing. And from it they make plungers, plunger bushings, pressure valve seats and valves themselves, pusher rollers, atomizer housings and other details that must have high hardness, contact strength and wear resistance. In general, if desired, the steel grade can be selected for any purpose.