BS 970/4-1970(1987) Chemical Composition of Deformation Steels, Stainless Steels, Heat Resistant Steels, and Valve Steels
BS 970 Part 4-1970(1987) is a British standard covering the chemical composition requirements of deformation steels, stainless steels, heat resistant steels, and valve steels. This part of the standard establishes the limits of percent carbon, manganese, phosphorus, silicon, sulfur, and chlorine in other alloying metals and a number of non-alloying metals in the above steels. It is up to the purchaser, producer, or user to determine all other characteristics such as heat treatment, surface finish, and form of the material, as well as the mechanical properties.
Deformation steels are alloys intended for use in the manufacturing of various articles where bending, forming, and other operations are performed in normal or moderate conditions. This group is comprised of non-alloy and alloy steels that exhibit good durability, formability and weldability.
The standard sets out the minimum and maximum chemical composition of non-alloy steels as 1.00percent by weight carbon and manganese, 0.040 percent by weight phosphorus and 0.050 percent by weight sulfur. The range of alloying metals for this group of steels ranges from 0.30 to 1.50 percent by weight for nickel, chromium, and molybdenum, and 0.20 to 0.60 percent by weight for vanadium, titanium, and aluminum. Non-alloy steels in this part of the standard may also contain 0.50 percent by weight maximum of any other element.
Stainless steels are alloys intended for use in the manufacture and maintenance of many articles, components and tools that are exposed to high temperatures and corrosive conditions. This group includes normal strength austenitic and martensitic stainless steels, as well as high strength steels.
The minimum and maximum chemical composition requirements for normal strength austenitic and martensitic stainless steels are 0.08 percent by weight carbon, 1.00 percent by weight manganese, 0.040 percent by weight phosphorus, 0.050 percent by weight sulfur, 17.0 percent by weight chromium, and 6.00 percent by weight nickel. The range of alloying metals for these steels ranges from 0.25 to 4.00 percent by weight for molybdenum, 0.20 to 0.35 percent by weight for nitrogen, 0.05 to 2.00 percent by weight for copper, and 0.90 to 1.20 percent by weight for silicon. High strength steels in this part of the standard may contain up to 0.50 percent by weight maximum of any other element.
Heat resistant steels are alloys intended for use in the manufacture of various products and tools that are subjected to high temperatures. This group includes both creep resisting steels and heat resisting steels.
The minimum and maximum chemical composition requirements for creep resisting steels are 0.10 percent by weight carbon, 0.30 percent by weight silicon, 0.040 percent by weight phosphorus, 0.050 percent by weight sulfur, 1.00 percent by weight manganese, 10.0 percent by weight chromium, 4.00 percent by weight nickel, and 1.20 percent by weight molybdenum. The range of alloying metals for these steels extends up to 0.50 percent by weight for niobium, 0.10 to 0.40 percent by weight for aluminum and titanium, 0.05 to 1.00 percent by weight for copper, and 0.45 to 1.50 percent by weight for tungsten. Creep resisting steels may also contain 0.50 percent by weight maximum of any other element.
The minimum and maximum chemical composition requirements for heat resisting steels are 0.08 percent by weight carbon, 0.30 percent by weight silicon, 0.040 percent by weight phosphorus, 0.050 percent by weight sulfur, 15.0 percent by weight chromium, 0.50 percent by weight aluminum, 0.20 to 1.00 percent by weight for nickel, 1.75 percent by weight for manganese, 0.60 percent by weight for molybdenum, 0.10 to 0.50 percent by weight for silicon, and 0.05 to 0.50 percent by weight for copper. Heat resisting steels may also contain 0.50 percent by weight maximum of any other element.
Valve steels are alloys intended specifically for use in the manufacture of spring, valve and double-edge tools. This group of steels includes annealed and age-hardenable alloys.
The minimum and maximum chemical composition requirements for annealed valve steels are 0.08 percent by weight carbon, 1.00 percent by weight manganese, 0.040 percent by weight phosphorus, 0.050 percent by weight sulfur, 10.5 to 11.5 percent by weight chromium, 0.75 to 1.40 percent by weight nickel, 0.40 to 0.70 percent by weight molybdenum, 0.25 to 0.60 percent by weight silicon, and 0.05 to 0.50 percent by weight for aluminum. Annealed valve steels may also contain 0.50 percent by weight maximum of any other element.
The minimum and maximum chemical composition requirements for age-hardenable valve steels are 0.25 percent by weight carbon, 0.50 percent by weight silicon, 0.040 percent by weight phosphorus, 0.050 percent by weight sulfur, 12.0 to 14.0 percent by weight chromium, 0.30 to 0.50 percent by weight aluminum, 0.20 to 0.60 percent by weight nickel, 0.60 to 1.20 percent by weight molybdenum, 0.40 to 0.80 percent by weight manganese, and 0.05 to 0.50 percent by weight for cobalt. Age-hardenable valve steels may also contain 0.50 percent by weight maximum of any other element.
BS970/4-1970(1987) provides a comprehensive set of guidelines for users, producers, and purchasers of deformation steels, stainless steels, heat resistant steels, and valve steels. The standard clearly sets out all of the minimum and maximum chemical composition requirements for each of these alloys, which allows for an accurate determination of the mechanical properties of the material, as well as other important characteristics such as form and surface finish.
