High carbon steel - steel with a carbon content of more than 0.6% (up to 2%).
| High carbon steel |
|---|
 |
| Phases of Iron Carbon Alloys |
|
| Structures of Iron-Carbon Alloys |
|
| Become |
|
| Cast iron |
|
Appointment and manufacture
Their main purpose is to obtain a wire rope . In the manufacture of patenting is applied, it is quickly cooled to obtain a fine-grained structure F + P ( ferrite + perlite ) and then subjected to cold deformation - drawing . The combination of ultrafine structure and riveting allows to obtain mechanical stress in the wire = 3000 - 5000 MPa. Due to the low viscosity, structural parts from this steel are not made . For the manufacture of bearings using alloyed with chromium (from 0.35 to 1.70% (mass.) Cr) steel grades SHKH4, SHKH15, SHKH15SG, SHKH20SG containing 0.95-1.05% (mass.) Carbon (GOST 801- 78. Bearing steel. Technical conditions). High-carbon steel is used to produce DSL (cast), DSK (chipped) and DSR (chopped) steel shot for shot peening - abrasive cleaning or hardening (GOST 11964-81. Iron and steel technical shot. General technical conditions). For the manufacture of springs, wire is used from steel KT-2 (0.86-0.91% (mass.) C) and 3K-7 (0.68-0.76% (mass.) C).
High carbon steels include, but are not limited to:
- Stamped steels - 0.6-1.0% carbon;
- some types of spring steels ;
- Tool steels , which in turn include high-speed steels .
Welding
Steels containing more than 0.6% carbon are welded significantly worse than medium carbon steel, in which carbon contains from 0.25 to 0.6%. High carbon steels are very prone to hardening and cracking in the transition zone and the heat affected zone. Therefore, when welding them, a tip with a lower thermal power of 75 l / h per 1 mm of metal thickness is used. The flame must be reducing or with a slight excess of acetylene . With an oxidizing flame, enhanced carbon burnout occurs and the seam is porous. Prevention of the appearance of hardened zones and cracks is carried out by preliminary and concomitant heating to 200-250 °.
The filler material is Sv-15 wire containing carbon from 0.11 to 0.18%, or Sv-15G according to GOST 2246-54. The left welding method is preferred. After welding, normalization is necessary.
It is also possible to obtain a deposited metal with high mechanical properties when welding these steels by using a filler wire with a normal carbon content, but alloyed with chromium (0.5 - 1%), nickel (2 - 4%) and manganese (0.5 - 0, 8 %). When welding metal with a thickness of less than 3 mm, preheating is not performed.