Spiral pipe manufacturers – processed look decarbonization doubt, the key in the heat treatment step. Because oxidation and decarbonization and wire are carried out simultaneously, thus, during the heat treatment as long as possible and make the wire less air can reach improved touch decarbonization intentions.
Example: A company selected two-lead groove oil quenching and tempering to deal with the valve spring wire, and achieved ambitious results. The production process is:
- The molten lead groove tempering (482 ℃). Because the wire does not touch the molten lead in the air, effectively prevent the decarbonization. This selection process needs treatment first question is how to prevent lead dust contamination.
- molten lead wire groove from austenitizing effect, advance the lead was heated to 871 ℃, wire lead in solution after complete austenitizing and then quenched into the sump.
- The first forming the outer atmosphere of the decarburization oxygen, water vapor and carbon dioxide and other oxidizing gases. When these oxidizing gases and heated outer wire touch, oxidation and decarbonization simultaneously attack; because affinity of carbon dissolved in the iron and these gases are relatively large, so the appearance of carbon on the first take off.
- The share of the furnace control carbon dioxide and carbon monoxide, in the balance, neither oxidized nor decarbonization; when carbon dioxide share of more than balance, seizures oxidation and decarbonization; below the equilibrium point is not the onset oxidation and decarbonization . Detailed numerical balance point according to the carbon content of iron and temperature calculation.
These gases from the furnace are usually packed to enter; the appearance of iron and steel products, rust and residue after cold drawn steel wire on the appearance, will differentiate into the furnace after heating, to generate some reaction oxidizing gas. We can intentionally manipulate the furnace atmosphere, so that in the recovery of health, will be able to effectively prevent the appearance of decarbonization.
Blown into the furnace neutral protective nitrogen is also a useful way. Nitrogen gas into the furnace can be oxidizing atmosphere severance some sections while being able to adhere to the furnace positive pressure air into the hamper, mitigate or prevent steel decarbonization.