There are several stainless steels containing nitrogen available to knifemakers. N680 is an inexpensive nitrogen steel.
The advantage of adding nitrogen to steel is corrosion resistance. The nitrogen frees chromium to provide corrosion resistance. N680 specializes in resisting corrosion caused by clorides i.e., salt, sweat, etc. The picture below shows the result of salt spray test:
The trade off for the low cost and extreme corrosion resistance is edge holding. The edge holding is better than 420, but not as good as 154CM. Excellent edge holding and extreme corrosion resistance are available but cost more.
N680 is easy to grind and heat treat. The steel is fine grained.
Paul Bos heat treated N680 for us. Cyrogenic treatment is highly recommended.
N680 was the first nitrogen stainless steel we tested. We have tested several since. Our current favorite is Z-FiNit. Z-FiNit steel outperforms N680 in every way except price.