Steel 20 refers to structural carbon quality steels.
Steel substitutes 20 – steel 15 and steel 25.
Designation of steels according to GOST 1050-88
When designating steel 20:
- the word "steel" is spelled in full,
- number 20 written separately (through a space),
- no full stop.
for instance, "Steel 20" or exactly according to the standard “steel grade 20” . This is the difference between the designations of structural carbon quality steels from ordinary carbon steels according to GOST 380-2005. The number after the word "steel" indicates the nominal carbon content in steel in hundredths of a percent. For steel 20 – this is 0,20 % carbon.
Unlike high quality steels (become 20, become 25 and others) ordinary steels in accordance with GOST 380-2005 abbreviated, fused and without points, eg, st3 or st4. If we really do the letter of the standard, then “steel grade St3”.
Steel 20: chemical composition
Chemical composition of steel 20 defines GOST 1050-88:
- carbon: 0.17-0.24 %;
- silicon: 0,17-0,37 %;
- manganese: 0,35-0,65 %;
- copper: no more 0,25%;
- nickel: no more 0,25%;
- arsenic: no more 0,08%;
- sulfur: no more 0,4%;
- phosphorus: no more 0,035%.
Steel structure 20
Typical steel structure 20 – pearlitic-ferritic. Hardened steel 20 it is possible to obtain the structure of lath martensite. Thermally hardened rolled steel 20 used for the manufacture of hardware products (strength class 8.8).
Technological properties of steel 20
- forging start temperature – 1280° C,
- forging end temperature – 750° C,
- cooling forgings – aerial.
Not prone to flock formation.
Not prone to temper brittleness.
Weldability of steel 20:
- with no restrictions;
- without preheating;
- without subsequent heat treatment.
Application of steel 20
Of steel 20 make:
- lightly loaded parts (fingers, axes, copiers, stops, gears);
- case-hardened parts for long-term operation, including, at temperatures up to 350 ° С;
- crane hooks;
- shells of bearings and other parts for operation under pressure at temperatures from minus 40 to 450 ° C.
Steel 20 after chemical-thermal treatment, they are used for parts with high surface strength (worms, worm pairs, gears). Steel 20 widely used for the production of pipeline fittings, steam lines, seamless high pressure pipes, welded rectangular and square profiles.
Types of steel supply 20
Types of steel supply 20:
- long products;
- calibrated bar;
- polished bar;
- thick sheet;
- thin sheet thin;
- forgings and forgings;