Austenitic Stainless Steel Ferritic Stainless Steel Martensitic Stainless Steel Precipitation Hardened Steel Duplex Stainless Steel (austenitic-ferritic)
Martensitic steel Martensite is a tough form of steel, and its properties mean it is a steel that can be heat-treated and hardened. However, it usually has reduced chemical resistance compared to austenitic steels. The benefits of martensitic steel mean that it offers a low cost, air-hardening metal with moderate corrosion resistance, which is easy to form, with a minimum chromium content of 10.5%. 
Uses of martensitic stainless steel include 1. Cutlery 2. Car parts 3. Steam, gas and jet turbine blades 4. Valves 5. Surgical Instruments
Precipitation Hardened Steel Precipitation Hardened Steel is the strongest steel grade, is heat treatable and has excellent corrosion resistance. Due to this, it is largely used for aerospace components, where extreme durability and reliability is needed from the part. PH steel is also used in the oil, gas and nuclear industries. This is because it offers a combination of high strength but generally a lower but workable degree of toughness. The most popular grades of precipitation-hardened steels are 17-4 PH and 15-5 PH. 
Common uses for PH hardened steel 1. Knives 2. Firearms 3. Surgical Instruments 4. Hand ToolsDuplex stainless steels, sometimes known as austenitic-ferritic stainless steel, have a two-phase metallurgical structure. Namely, duplex stainless steel contains both austenitic and ferritic phases. The strength of duplex stainless steel is higher than typical austenitic stainless steel and has additional corrosion resistance. Duplex grades have a lower molybdenum and nickel content, reducing costs compared with austenitic grades. Consequently, duplex alloys are often used in heavy industrial applications such as the petrochemical industry.Factors to consider when choosing a stainless steel grade There are usually multiple factors that need to be considered when choosing a material for any project. With many different stainless steel grades available, it can be challenging to narrow down your choice. However, if you consider the following factors, you should be in a position to determine which grade is best for you.Strength Often tensile strength is a critical factor in determining the best material for your project. We recommend developing an understanding of the forces and loads that will be experienced by your parts and comparing this against the various tensile strengths on offer. This will help you eliminate any materials that won’t offer the required strength.Heat treatment If you have specific hardness requirements for your parts, you may wish to consider heat treatment. Bear in mind that whilst heat treatment improves the hardness of your parts, this may come at the expense of other mechanical properties. Also, note that austenitic stainless steels cannot be heat-treated, thus eliminating this category from your material choice.Magnetism Whether a part is magnetic or not is an essential factor to consider in specific projects. Remember that austenitic steel is non-magnetic due to its microstructure.Cost If cost is the most important factor for your project. Bear in mind, however, that the material cost is just one part of the overall cost. Try to reduce cost by reducing the number of machining operations and simplifying your parts as much as possible.Availability of grade When arranging a quote with CNC machining companies such as Get It Made, check to see which stainless steel grades they offer; there may be common grades they stock or can easily source. Avoid specifying overly niche grades or branded materials as this can increase costs and lead times. You can find Get It Made’s most common material grades on our individual process pages.