DIN 91-81 Part II SEAMLESS PREISION STEEL TUBES 1.Field of application This defines the technical delivery conditions for seamless precision steel tubes according to DIN 91 Part 1 which are made from the steel grades listed in section 5. Tubes according to this are mainly used where accuracy to dimension and, possibly, small wall thicknesses and good surface condition are required. hemical composition (%) 1 Grade Mfg. Process Si Mn P S Ni r Mo Others 1 St0Si S 0.10Max 0.0Max 0.55Max 0.00Max 0.00Max - - - - 1 St0A1 S 0.10Max 0.05Max 0.55Max 0.00Max 0.00Max - - - Al deoxydized 1 St5 S 0.17Max 0.5Max 0.0Max 0.050Max 0.050Max - - - - 1 St5 S 0.1Max 0.5Max 0.0Max 0.050Max 0.050Max - - - - St5 S 0.Max 0.55Max 1.60Max 0.050Max 0.050Max - - - - 1
1old-finished/hard old-finished/soft Annealed Normalized Grade Material number Tensile Test MPa or N/mm Min Yield point Tensile Strength Remarks (Similar to JIS) - 00Min St0Si 1.011 St0Al 1.01 St5 1.008 St5 1.008 St5 1.0580-55Min - 85Min 15 95~0-00Min - 55Min - 85Min 15 95~0-0Min - 70Min - 15Min 5 0~70-50Min - 70Min - 90Min 55 0~570-590Min - 50Min - 90Min 50 90~60 (STKM11) (STKM11) (ST8) (STKM1) (STKM19)
Welded Steel Tubing and Pipe-orresponding to DIN 91-1 Wall thickness s Nominal dimension 0.5 0.8 1 1. 1.5 1.8..5.8.5 5 5.5 6 7 8 9 10 1 1 16 18 0 5 Permissible deviation Outside diameter da Nominal dimension Permissible deviation 5 6 7 ±0.1 8 9 10 1 ±0.08 1 15 16 18 0 5 6 8
0 5 8 ±0.15 0 5 8 ±0.0 50 55 60 65 70 75 80 85 90 95 100 110 10 10 10 ±0.5 ±0.0 ±0.5 ±0.0 ±0.5 ±0.50 ±0.70 150 ±0.80
160 170 180 190 00 0 0 ±0.90 ±1.0 ±1.0 60 ±1.0 1) For outside diameters of nominal dimensions and 5 mm, the permissible deviation from the nominal dimension s/d s/d s/d s of the wall thickness is ± 0 % For outside diameters of nominal dimensions 6 to 8 mm, the permissible deviation =1/60 =1/0 =1/0 from the nominal dimension s of the wall thickness is ±15%.. Quality grade The tubes are supplied in the following quality grades: A B precision steel tubes intended primarily for mechanical stressing, without any particular quality requirement and without acceptance test certificate precision steel tubes intended primarily for mechanical stressing, with special requirement and exclusively with acceptance test certificate precision steel tubes with special requirement according to section 1. Theses requirements and corresponding tests must be agreed, with the customer having to specify his requirements at the time of enquiry and on ordering Table 1. Steel grades Quality grade A and B Steel grade ode number St 0 Si St 0 Al St 5 St 5 St 5 Material number 1.011 1.01 1.008 1.008 1.0580
All steel grades according to quality grade A and B, as well as other steels, e.g. according to DIN 1651 DIN 17 100 DIN 17 00 DIN 17 10 DIN 17 11 DIN 17 1 6. hemical composition 6.1. Table contains data on the chemical composition of the steels. Small departures from these data which apply to the ladle analysis, are permissible if they do not impair the properties of the steel when in use. 6.. In carrying out subsequent testing on the finished tube, the maximum permissible contents in terms of carbon, phosphorus and sulfur as defined by the ladle analysis of table may be increased: - in the case of deviations due to sampling and method of analysis by + 5 % - in the case of deviations due to segregation: for rimming steels by + 0% for killed steels by + 5 % of the particular maximum content. Table. Steel grades and chemical composition of the steels (ladle analysis) Steel grade hemical composition, % Symbol Material number max Si max Mn P max S max St 0 Si 1.011 0.10 0.0 0.55 0.00 0.00 St 0 Al 9) 1.01 0.0 0.05 0.55 0.00 0.00 St 5 1.008 0.17 0.5 0.0 0.050 0.050 St 5 1.008 0.1 ) 0.5 0.0 0.050 0.050 St 5 1.0580 0. 0.55 1.60 0.050 0.050 1) This steel is deoxidized using aluminum. ) In subsequent testing on the individual tube, the -content must not exceed 0.5%.
7. ondition on delivery The tubes are supplied in one of the conditions listed in table. Other conditions on delivery are specified in table 9 (quality grade ). Term Symbol Explanation Table. onditions on delivery old-finished/hard (cold-finished as-drawn) old-finished/soft (lightly cold-worked) BK BKW No heat treatment after the last cold-forming process. The tubes therefore have only low deformability. After the last heat treatment there is a light finishing pass (cold drawing) With proper subsequent processing, the tube can be cold-formed (e.g. bent, expanded) within certain limits. Annealed GBK After the final cold-forming process the tubes are annealed in a controlled atmosphere or under vacuum. Normalized NBK The tubes are annealed above the upper transformation point in a controlled atmosphere or under vacuum. 8. Mechanical and technological properties 8.1. The mechanical properties depend on the condition on delivery as defined in table. 8.. In technological testing (drift expanding test and flattening test) the samples must comply with the requirements of sections 11... and 11... 8.. In the case of other steel grades and/or other conditions on delivery then those specified in tables, and 8, the mechanical and technological properties must be mutually agreed. In these cases, the tubes are supplied according to quality grade. 8.. The steels listed in table are deemed to be suitable for welding because of their chemical composition and metal lurgical treatment. In the BK or BKW conditions on delivery, the mechanical properties are modified in the zone which has been subjected to heating. This should be taken into account (see DIN 858 Part 1) in assessing the weldability of a component. Table. Mechanical properties of the tubes at room temperature ondition on delivery Steel grade old-finished/hard old-finished/soft Annealed Normalized (BK) ) (BKW) ) (GBK) ) (NBK) ode number Material number Tensile strength Rm N/mm Elongation at repture A5 % Tensile strength Rm N/mm Elongation at repture A5 % Tensile strength Rm N/mm Elongation at repture A5 % Tensile strength Rm N/mm Upper yield point ReH N/mm Elongation at repture A5 %
min min min min min min min min St 0 Si 1.011 00 8 0 1 80 0 90 to 0 15 0 St 0 Al 1.01 00 8 0 1 80 0 90 to 0 15 0 St 5 1.008 0 6 70 10 15 5 0 to 70 5 5 St 5 1.008 50 5 70 8 90 1 0 to 570 55 1 St 5 1.0580 590 50 7 90 90 to 60 55 ) The yield point for the annealed (GBK)condition on delivery is at least 50% of the (ultimate) tensile strength. Depending upon the degree of deformation in the drawing operation, the yield point of tubes delivered in the cold-finished/hard (BK)and cold-finished/soft(bkw) conditions, may be increased to a level close to the tensile strength. In calculating the yield point, the following values are recommended: cold-finished/hard condition on delivery 80% of the tensile strength, cold-finished/soft condition on delivery 70% of the tensile strength. ) In the case of tubes of outside diameter 0 mm, the wall thickness of which is mm, the minimum value of the yield point is 10 N /mm lower. JIS ASTM BS DIN NF ISO Grade Type Grade Type Grade Type Grade Type Grade Type Grade Type Index G5 STKM11A A51 MT1010 1717 ERW1 91 St0Si 0 R8 017 A51 MT1010 St0A1 05 " 9 St8 06 " RSt8 9 St8 USt8 RSt8 STKM1A A51 MT1015 1717 ERW 91 St7-0 R A51 MT1015 6 HFS RSt7-05 " " STKM1B A51 MT1015 9 St7-06 " " A51 MT1015 Ust8-
A519 MT1015 RSt- STKM1 1717 EW A9- TU7b " FS A9-7 TU7b 6 FS " FSA STKM1A A1 MT100 1717 ERW 91 St5 A9- TU7b 97 TS A51 MT100 9 St- A9-0 TU7b 0 R7 " 9 St- A9- TU8b 05 " " STKM1B A51 MT100 06 " " STKM1 1717 EW " FS 6 FS STKM1A A51 MT100 6 HFS 97 TS9 0 R " STKM1B 6 HFS5 05 R STMK1 06 " " STKM15A A51 100 A519 100 STKM15 STKM16A A519 100 A9-11 TUX5 A9-1 TUX5 STKM16 STKM17A A519 1050 6 HFS8 STKM17 6 FS8
STKM18A A519 1518 1717 ERW5 A9-10 TU5b A9-11 TU5b A9-1 TU5b STKM18B A9-1 TU5b A9- TU5b A9-6 TU5b STKM18 A9-0 TU5b A9-1 TSa " TS7a A9- TS18M5 STKM19A A519 15 91 ST5 97 TS18 9 ST5-98 Gr.1 9 ST5-0 R50 05 R50 06 R50 STKM0A