On 2018-08-08 14:48:54
carburizing nitriding problems and solutionsThe hardness or depth of the nitriding surface is not enough
(1) it may be that the chemical composition of the steel is not suitable for nitriding.
(2) it may be that the tissue before nitriding is not suitable
(3) it may be that the temperature of nitriding is too high or too low
(4) the temperature or inhomogeneous flow of gas in the furnace
(5) insufficient flow of ammonia
(6) the time of nitriding is not long enough
The bending of the nitriding workpiece is very severe
(1) the relaxation annealing treatment before nitriding is not done well
(2) poor geometric design of workpieces, such as asymmetry, excessive thickness and other factors.
(3) the placement of the processed workpiece in nitriding is incorrect
(4) uneven surface properties such as uneven cleaning or uneven surface temperature.
Cracking and peeling off of nitriding workpiece
(1) the decomposition rate of ammonia exceeds 85%, which may occur.
(2) there is a decarburization layer on the surface of the workpiece before the nitriding treatment
(3) there is an obvious sharp angle in the design of the work piece
(4) when the white layer is too thick
Over thickness of white layer of nitriding workpiece
(1) the temperature of nitriding treatment is too low
(2) this phenomenon may occur when the decomposition rate of ammonia is below 15%.
(3) the cooling process is not appropriate
The instability of ammonia decomposition rate in nitriding treatment
(1) decomposition rate measuring device pipeline leakage
(2) there are too few parts in the nitriding process to enter the furnace
(3) the change of pressure in the furnace leads to the change of ammonia flow
(4) improper action of catalyst
How can the workpiece be machined to prevent carburizing?
(1) copper plating method, copper layer above 20mm thickness
(2) drying after coating the coating agent, the copper powder can be suspended in sodium silicate solution.
(3) drying after coating carbon coating agents, mainly using borax and organic solvents.
(4) coating method of iron oxide and clay mixture
(5) use sleeve or sleeve screw
Insufficient hardness of the workpiece after carburization
(1) the cooling rate is not enough, which can be cooled by spray cooling or brine cooling.
(2) lack of carburization and the use of strong carburizing agent
(3) insufficient quenching temperature
(4) the decarbonization phenomenon caused by heating during quenching can be directly quenched by salt bath furnace.
Carburized layer stripping phenomenon
(1) carbon content concentration gradient is too large. Diffusion annealing should be applied.
(2) there is no intermediate layer, and the rate of carburizing should be eased.
(3) the carburizing layer before grinding can be considered in the case of carburizing.
(4) repeated carburization may also cause the phenomenon of carburizing layer peeling.