Stainless Steel is generally defined as a steel having at least 10% Chromium in conjunction with other alloy elements. They are resistant to corrosion or rusting associated with exposure to water or moist air.
There are four main groupings of Stainless Alloys commonly used in the oil industry: Austenitic, Martensitic, Duplex, & Precipitation Hardening.
Stainless grades are not hardenable by heat treatment and can only be strengthened through cold working. The grades in this category are limited to low strength levels and are highly corrosion resistant with excellent low-temperature toughness.
Stainless grades are hardenable through the quench and temper heat treat process and can achieve much higher strength levels. The corrosion resistance is less than the austenitic grades, but adequate, depending upon the environment. Toughness is less than shown in the Austenitic grades.
Stainless is a mixture of both Ferritic and Austenitic structures. This family of alloys has good corrosion resistance and exhibits higher strengths than the austenitic grades (roughly doubled in the annealed condition) with good corrosion resistance and excellent toughness. These alloys cannot be hardened by heat treatment, but can be cold worked to improve strength.
Stainless are alloys that can achieve very high strength, while still maintaining good corrosion resistance and toughness. They are annealed and hardened by aging through the addition of Copper, Aluminum, Titanium, Niobium, and Molybdenum.
