After nitriding treatment, molds or workpieces develop a surface layer of hardened tissue with high hardness and certain corrosion resistance.

At 525℃ nitrogen treatment, the surface hardness of the workpiece is approximately 1250HV. The effect of nitriding time on the diffusion layer is as shown in the table below. Nitriding Time (hours): 20 30 60, Nitriding Layer Depth (mm): 0.25 0.30 0.35.

The surface hardness of the workpiece after soft nitriding at 570℃ is approximately 950HV. Typically, a soft nitriding process for 2 hours results in a hardening layer depth of 10-20um. Machining blanks or parts in low-temperature tempering state can lead to grinding cracks. To prevent cracking, use small feed rates for multiple grinding passes, and supplement with excellent water cooling conditions.

Complex shapes or large-sized molds often encounter cracking during wire cutting processing. To prevent cracking, it is recommended to use air quenching and high-temperature tempering treatment to reduce thermal stress, or perform pre-machining of the mold blank cavity.