In the fastener industry the term “18-8” is often used as a designation for a bolt, nut, or washer manufactured from 300 series stainless steel material that has the 18% chromium/8% nickel alloy mixture. While all 300 series stainless steels share this 18/8 mix, slight differences in chemical composition between the different grades of the 300 series do make certain grades more resistant than others against particular types of corrosion. “18-8” is not an actual specification, as it only refers to two different alloys in the steel. This “18-8” call out is referring to the 18% chromium/8% nickel alloy mixture of the steel. The term “18-8” is often used to designate products made from 300 series stainless. They can be hardened by cold working the material (“work hardening.”).They cannot be hardened by heat treatment.Their carbon content is generally held to a maximum of 0.08%.The 300 series designation contains many different compositions of alloy steel (303, 304, 305, 316, 321, 347, etc.) but the common factors among them are: There are many different types of stainless, but by far the most popular and widely used are the 300 series stainless steels, also known as the austenitic stainless steels. This layer is what makes the steel “stainless.” Higher levels of chromium and the addition of other alloying elements such as molybdenum and nickel enhance this protective barrier and further improve the corrosion resistance of the stainless steel. At and above this level of chromium, a complex chrome-oxide surface layer forms that prevents further oxygen atoms from penetrating into the steel and thus protects the iron in the matrix from rusting. “ Stainless Steel” is the general name for a large family of alloy steels that contain at least 10.5% chromium as part of their composition. ☏)ġ8/8 stainless steel is widely used in petroleum & chemical industry, metallurgical machinery, aerospace industry, food processing equipment, instruments, household appliances and hardware manufacturing industries.ġ8/8 steel is made into a great many intermediate products such as steel sheet & plate, steel tube & pipe, steel bar & flat, rod & wire, etc.įinal products such as all kinds of kitchenware, tableware, medical device, machinery and parts, wire mesh, filter, architectural and decorative metal products, etc.To answer this question, you first need to know some basic information about stainless steel.☏)Ĭoefficient of thermal expansion (CTE), 10 -6/K (μin./in.☏)Įlastic modulus (Modulus of Elasticity), GPa (10 6 psi).The tables below list 18-8 stainless steel mechanical properties including yield strength, tensile strength, elongation and hardness, etc.ġ8-8 stainless steel physical properties including density, melting point, magnetic, specific heat capacity, electrical resistivity, modulus of elasticity (elastic modulus), thermal diffusivity, thermal conductivity and coefficient of thermal expansion. Chemical Compositionġ8-8 stainless steel composition is given in table below. For full datasheet and specification, please view AISI 304, 304L. The tables below list the 18/8 stainless steel properties including chemical composition, physical and mechanical properties. ![]() ![]() 18/8 steel is the most widely used material, has excellent corrosion resistance in mild environments, and has good weldability and mechanical properties. The steel containing 18% chromium and 8% nickel includes 304 and its variants 304L, 304N and 304LN. 18/8 stainless steel is also konwn as 304 stainless steel, it refers to the chemical composition of steel containing 18% chromium (Cr) and 8% nickel (Ni).
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