When purchasing a stainless steel folding knife, or any other knife online, you might see information about the grading of its steel. Here is an explanation of some of the grades you might see, so you can make a good purchasing decision and find a knife suitable for your needs.
The primary families of stainless steel help to define its potential properties.
- Austenitic – The most popular and widely-used family of steels. These steels typically include chromium and nickel, with certain grades incorporating manganese and molybdenum as well. The grades range in the 200s and 300s mostly. Although not suitable for knives, they offer excellent corrosion and creep resistance. This family of metals is very well suited to welding and finds use in a number of industries.
- Ferritic – These steels tend to be more cost effective than other families, as a result of their low nickel content. Indoor applications are a good choice for these metals, as well as any other applications where visual appeal isn’t as important. Despite their fairly undesirable aesthetic, they are suited for a range of tasks.
- Duplex – These steels are relatively modern and combine the properties of a number of austenitic and ferritic stainless steels. The alloy can vary their use, allowing for some very specific steels with enhanced weight, toughness, or tensile strength. These may be resistant to corrosion when certain alloys are used, making these steels suitable for offshore use.
- Martensitic & Precipitation Hardening – Although relatively uncommon compared to other steel types, these are of particular use in cases where steel requires a hard edge. As a result, good knives use this steel in order to retain their structure and keep a sharp edge for longer. Manufacturers of razors, scissors, and medical tools also make use of this steel family.Owing to its suitability to tempering and hardening, as a result of added carbon, this also allows knife manufacturers to finely-tune the properties of a blade.
The automotive industry set up this common grading standard in order to demonstrate standardize requirements for different steel grades. There are a lot of numbers to learn, so here are a couple of important ones to look out for:
- 420 – This steel can sharpen to a hard edge and features excellent polishing potential, which makes it ideal for use as cutlery. Sparkling steel knives and forks are hard, martensitic chromium alloys which make your tableware shine.
- 440C – A highly-prized grade of steel for knife-making. It can sharpen to a very fine edge, offering excellent strength and edge retention. Variations in the industry may have their own brand names, so check to see their comparable SAE grades for accurate information.
Other 440 types may also be suitable for knife-making in specific circumstances. Certain use-cases, such as diving may also require different steel grades in order to prevent corrosion. However, when choosing a standard, everyday carry stainless steel folding knife for sale, always look for 440C steel as a mark of quality and strength.