《Standards and designation of steels - EN standard 2pp》.pdf

25/11/2012 Classification and designation of Steels – EN Standard G. Maizza Automotive Engineering Car body and Inner Design I. La classificazione Steels can be classified using different criteria: • by alloying element content • by heat treatment: steels for tempering, carburizing, nitriding, etc. • by applications: structural, construction, tooling, etc. • by degree of workability: “automatic”, cold forming, etc. Typically standards do not follow only one criterion 1 25/11/2012 I. Classification- UNI EN 10020 If at least 1 element content limits, the steel is named as alloyed, otherwise is said unalloyed Element Limit, % (in mass) Unalloyed steels (plain carbon steels): Mn 1,65 • “quality” • “special” - with specifications: i.e. resilience, Cr 0,3 hardenability, purity (bounded inclusion content) Ni 0,3 Alloyed steels : • “quality”: weldable with small grain size, for Mo 0,06 railways, for sheet being cold formed with deep W 0,3 drawing ability, for magnetic use, etc. • “special” - olters: tempering steels or carburizing, V 0,1 for tools, rapid steels, etc. Acciai inossidabili (inox): Cr 10,5%, C 1,2% II. Alfanumeric designation A. Based on mechanical/physical and uses B. Based on chemical composition