Let's take a look at the specific conditions of the carburized layer. If the depth and carbon concentration and gradient of the whole layer are all right, it means that there is a problem with cooling, and if there is a problem, it means that there is a problem with carburizing.

Cooling to 870 degrees, cooling to room temperature in slow cooling pit, and then heating salt bath quenching, is it insufficient exhaust time, they generally exhaust in about 10 minutes, some less than 10 minutes!! The carbon potential in the furnace is not uniform. In addition, they basically did not set diffusion time for carburizing, and the samples cooled down after qualified. The concentration gradient must not be qualified, but this should not have much to do with uniformity. This is mainly caused by insufficient exhaust time and uneven atmospheric circulation, which has little relationship with furnace loading.

It is necessary to add point diffusion time, and the problem may be that there is no diffusion. During secondary quenching, the thickness of carbon layer is uneven due to uneven diffusion.

Some people think that the amount of workpiece assembly is too small and the seepage layer is uneven. After cooling down, we should check whether it is the upper layer or the lower layer, and which area of the layer should we find out. In some factories, when carburizing, the workpiece gap is 1-2 mm, almost close to each other, and there is no such situation that the carburizing layer is uneven. Another is how much the difference of the carburizing layer is, for example, 0.2 mm difference between the upper and lower pans of the well furnace, which is even normal. The quantity of the furnace is not much, and the exhaust time is not too big. The exhaust time is usually 15-30 minutes after the temperature and then enriched gas (kerosene or propane) is enough. Solve the circulating gas flow in the furnace, increase the permeability at the bottom of the layer. Intensive infiltration and diffusion time is 3:1, which is conducive to accelerating infiltration rate. In addition, a better carbon control system can be replaced.