CMD-III/16:1786 - BIS

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marked with certification mark of the Bureau.5.1 On the basis of tests and inspection results, decision regarding conformity or otherwise of lots of steel to the requirements ofIS 1786:2008 shall be taken as indicated below:5.2 CHEMICAL COMPOSITION : Chemical Composition of the differentGrades of high strength deformed steel bars and wires shall conform to the requirements as per Clause 4.2 of the specification.STI/1786/R-1/9Sept. 20085.3 FREEDOM FROM DEFECTS: All finished steel shall be rolled to thedimensions and mass specified. The finished material shall be free from harmful surface flaws, laminations, rough and imperfectedges and all other defects as has been stipulated in clause 4.3.1 of the specification. The defective material shall be sorted out andshall not be covered under the scheme unless the defects are satisfactorily removed by recognized methods. The material thus rectifiedshall be re-examined and covered under the scheme if found satisfactory.5.4 TENSILE TEST: Periodic calibration should be done of the tensile testingmachines. The frequency of such calibration should preferably be once in six months, andin any case not less than once in a year.5.5 The frequency of nominal mass tensile, Bend & Re-Bend tests shall be as given below if the material is rolled from one cast. Aseparate test shall be made from each type of finished bars and for each variation in size.------------------------------------------------------------------------------------------------------------Nominal Size Quantity------------------------------------------------------------------------------------------------------------For casts/heats below For casts/heats over100 tonnes 100 tonnes(1) (2) (3)
For All Sizes 2 Per Cast 3 Per Cast5.6 Where the material has been rolled from ingots/ billets ,segregated gradewise (see 4.5 above) one tensile ,bend and rebend testshall be made from every 10 tonnes or part of the material in the lot.5.7 The location on the finished product from where the test samples are to be takenand the procedure for the preparation of the test pieces from test samples shall bein accordance with clause 9.1, of the specification.5.8 RE-TEST - If any one of the test pieces first selected fails to conform to any of the tests as given in the specification, two furthersamples shall be selected for testing in respect of each failure. Should the test pieces from both these additional samples pass, thematerial represented by the test samples shall be deemed as fit to be covered under BIS Certification Marks Scheme.STI/1786/R-1/9Sept. 20085.9 DEFORMATIONS AND SURFACE CHARACTERISTICS - For high strength deformed bars/wires, the mean area of ribs(in mm 2 ) unit length in mm above the core of the bar/wire, projected on a plane normal to the axis of the bar/wire calculated inaccordance with 5.4 of the specification shall not be less than the following values:0.12 Ǿ for Ǿ < 10 mm0.15 Ǿ for 10 mm < Ǿ < 16 mm0.17 Ǿ for Ǿ > 16 mmWhere Ǿ is the nominal diameter of bar/wire in mm.The mean projected area of transverse ribs alone shall be not less than one-third of the values given above.The calculations for mean projected area Ar may be done as per Cl.5.4, 5.5 and 5.6 of the specification. Frequency of suchcalculation shall be once in a day for each size rolled.5.9.1 When subjected to pull-out test in accordance with IS 2770(Part-1) of the specification the bond strength calculated from theload at a measured slip of 0.025 mm and 0.25 mm for deformed bars/wires shall exceed that of a plaint round bar of the same
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CMD-III/16:1786 - BIS

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