What is the reason for the high carburizing concentration

What are the causes and hazards of high carburizing concentration

Causes and hazards of excessive carburizing concentration:

If the carburizing is heated sharply, the temperature is too high, a new carburizing agent is used when solid carburizing, or the strong carburizing agent is used too much will cause the carburizing concentration to be too high. As the carbon concentration is too high, massive coarse carbides or network carbides appear on the surface of the workpiece. Due to the production of this hard and brittle structure, the toughness of the carburized layer drops sharply. In addition, high-carbon martensite is formed during quenching, which is prone to grinding cracks during grinding.

Prevention methods

① It cannot be heated rapidly, and proper heating temperature should be used to prevent the grains of steel from growing. If the grains are coarse during carburizing, normalizing or two quenching treatments should be used after carburizing to refine the grains.

②Strictly control the uniformity of the furnace temperature and avoid excessive fluctuations. Special attention should be paid to solid carburizing in the reverberatory furnace.

③When solid carburizing, the carburizing agent should be used in a ratio of new and old. It is best to use 4-7% BaCO3 as the permeabilizing agent instead of Na2CO3