Some of the early stainless knives were 300 series with Nickel added. These knives were not hardenable and had soft edges. Other early stainless knives were made of high Carbon 440-C which was hardenable and hard to sharpen on natural stones like Arkansas (micro-crystaline quartz).
On account of the push back on early stainless, most cutlery companies stopped using the word stainless in their ads. 400 series (hardenable) stainless steels are really semi stainless, but they hold a good edge.
300 series stainlesses like 18-8 (18% Chrome/8% Nickel) are highly resistant to corrosion, exhibit little Ferro-magnetism (attraction to a magnet), and cannot be hardened. Carpenter 20 (320 SS) is so resistant to corrosion that it is used to make the chambers in which Sulfuric Acid is made.
400 series stainlesses like 440-C (16% Chrome/0% Nickel) are subject to surface rust, stick to a magnet, and can be hardened. Because of the extensive use of electro-magnetic induction cook tops in countries with high energy costs, premium pots and pans are made in 3 layers.
The bottom of the pan is made of 400 series SS so it can be excited by the E/M coil. The middle layer is Copper or Aluminum to spread the heat uniformly. The inside of the pan is made of 300 series SS so it won’t react with foods (especially acid foods).
In conclusion, keep your 420HC away from hot tomato sauce (or rinse thoroughly).
On account of the push back on early stainless, most cutlery companies stopped using the word stainless in their ads. 400 series (hardenable) stainless steels are really semi stainless, but they hold a good edge.
300 series stainlesses like 18-8 (18% Chrome/8% Nickel) are highly resistant to corrosion, exhibit little Ferro-magnetism (attraction to a magnet), and cannot be hardened. Carpenter 20 (320 SS) is so resistant to corrosion that it is used to make the chambers in which Sulfuric Acid is made.
400 series stainlesses like 440-C (16% Chrome/0% Nickel) are subject to surface rust, stick to a magnet, and can be hardened. Because of the extensive use of electro-magnetic induction cook tops in countries with high energy costs, premium pots and pans are made in 3 layers.
The bottom of the pan is made of 400 series SS so it can be excited by the E/M coil. The middle layer is Copper or Aluminum to spread the heat uniformly. The inside of the pan is made of 300 series SS so it won’t react with foods (especially acid foods).
In conclusion, keep your 420HC away from hot tomato sauce (or rinse thoroughly).