STEEL TUBE AND PIPE HANDBOOK - February 2012

9 Steel quality groups accord- ing to chemical composition NON-ALLOY STEELS Element contents beyond the tabulated values STAINLESS STEELS Max. contents C 1,2% Min. contents Cr 10,5% Ni contents less than 2,5% or Ni contents over 2,5% OTHER ALLOY STEELS Non stainless steel, contents of, at least, a single element within the tabulated values. Classification of steel within the main quality groups Classification of steels according to EN 10020 NON-ALLOY QUALITY STEELS For general requirements: - impact energy - grain size - formability ALLOY QUALITY STEELS fine-grain steels steels for rails and reinforcing steels for demanding use alloy steels by Cu steels for electronics NON-ALLOY SPECIAL STEELS Designed for quenching and tempering and surface hardening etc. Minimal val- ue of impact energy guaranteed. Low con- tents of non-metallic inclusions. BASIC CHARACTERISTICS Corrosion resisting steels Creep resisting steels Heat resisting steels ALLOY SPECIAL STEELS structural steels for pressure vessels for anti-friction bearings tool steels high-speed steels special physical characteristics + + Designation system for steels according to EN EN 10027 – 1 Steel names (ISO/TS 4949) Abbreviated designation system Principal symbols EN ECISS IC10 Additional symbols EN 10027 – 2 Numerical system According to EN 10027 – 1 the steel names divide into the two main groups: • Group 1 – steel designated according to the usage and me- chanical properties • Group 2 – steel designated according to the chemical com- position. These further divide into the four subgroups. Group 1 - see also page 109. S – structural steel (for general usage) P – steel for pressure equipments L – steel for pipelines E – steel for machine parts (the subsequent number stands for the minimum yield value in v N/mm 2 ) B – concrete reinforcing steel Y – prestressed concrete reinforcing steel R – steel for rails H – high strenght steel for cold rolled flat products D – sheet products frommild steel for cold forming – cold rolled T – thin sheets and strips for packing M– sheets and strips for electronic industry The first four steel kinds are used for tubes. Group 2 – includes 4 subgroups • non-alloy carbon steel (with controlled C content) – desig- nation: Letter C and the number corresponding to the centupli- cate of the average range specified for carbon content (C22) • Non-alloy carbon steel containing Mn > 1% and al- loyed steel with the contents of individual alloying elements less then 5% – designation: a) number corresponding to the carbon contents centuplicate b) chemical symbols of alloying elements arranged accord- ing to the descending content of elements c) numbers set out following the alloying elements content. Mean element content, multiplied by index from table and approximated tu higher number (25CrMo4) . • alloy steel with alloying addition content (a minimum of a single element over 5%) – designation: a) characteristic letter X (X11CrMo9-1) b) number – centuplicate of the mean carbon content c) chemical symbols of alloying elements d) numbers set out following the alloying elements content. Mean element content approximated tu higher number. • high-speed steel – designation a) characteristic letters HS (HS 6-5-2) b) numbers set out following the alloying elements content Regulation EN ECISS IC10 sets out additiional symbols for steel (Group 1 and 2). These symbols form the suffixes to the steel mark end (e.g. S 275 J0). The supplementary sym- bols for steel products are detailed in Table 1, 2 and 3, and plus (+) must separate them from the preceding sym- bols – e.g. S 275 J0+A. Symbols for steel tubes G – other characteristics (according to the need 1 to 2 digits) H – hollow profile or steel for higher temperatures according to steel type (S, P) L – steel for low temperatures R – steel for room temperatures (ambient temperature) M– thermo mechanically rolled N – normalized annealing or normalized rolled Q– quenched T – steel for tubes EN 10027 – 2 includes the numerical system. The first digit is 1 – steel, followed by two digits of the steel group and the steel sequence number (1.0402, 1.7218, 1.7386, 1.3339) . • Classification of steels see also ISO 4948-1 and ISO 4948-2