ABS

ABS RULES FOR TESTING AND CERTIFICATION OF MATERIALS . 2007 21 P A R T 2 C H A P T E R 1 Materials for Hull Construction S E C T I O N 2 Ordinary-strength Hull Structural Steel 1 Ordinary-strength Hull Structural Steel (1996) The requirements in this subsection are intended for products of the following thicknesses. Plates and Wide Flats up to and including 100 mm (4.0 in.) Sections and Bars up to and including 50 mm (2.0 in.) 3 Process of Manufacture The steel is to be made by one or more of the following processes: open-hearth, basic-oxygen, electric-furnace, vacuum-arc remelt, electro-slag remelt, or such other process as may be specially approved. The steel may be cast in ingots or may be strand (continuous) cast. The ratio of reduction of thickness from a strand (continuous) cast slab to finished plate is to be a minimum of 3 to 1 unless specially approved. Data in support of mechanical properties, weldability and compliance with the Rules in all respects are to be submitted by the steel manufacturer for review and approval when new or special steels or production methods are proposed or when new steel mills begin production. 3.1 Plates Produced from Coils For coiled plate, the manufacturer or processor is to submit supporting data for review and approval to indicate that the manufacturing, processing, and testing will provide material which is in compliance with the Rules. 5 Chemical Composition 5.1 Ladle Analysis The chemical composition is to be determined by the steel manufacturer on samples taken from each ladle of each heat and is to conform to the applicable chemical requirements of the grades of steel listed in 2-1-2/Table 1. 5.3 Product Analysis When product (check) analysis is required, the chemical tolerances of ASTM A6 or of other nationally recognized standards are to be applied. Part 2 Rules for Materials and Welding Chapter 1 Materials for Hull Construction Section 2 Ordinary-strength Hull Structural Steel 2-1-2 22 ABS RULES FOR TESTING AND CERTIFICATION OF MATERIALS . 2007 5.5 Special Compositions Material differing in chemical composition, deoxidation practice, mechanical properties or heat treatment from that shown in 2-1-2/Table 1 will be subject to special approval. 5.7 Fine Grain Practice Where steel is required to be made using fine grain practice, the requirement is to be met by adding aluminum, unless some other method is specially approved. The fine grain requirement may be determined by one of the following methods. 5.7.1 A McQuaid-Ehn austenite grain size of 5 or finer in accordance with ASTM E112 for each ladle of each heat, or 5.7.2 Minimum Acid-soluble Aluminum content of 0.015% or minimum total Aluminum content of 0.020% for each ladle of each heat. 7 Condition of Supply (2005) The conditions of supply are to be in accordance with the requirements in 2-1-2/Table 5 and the following: Controlled manufacturing processes require approval for each plant and combination of grade and thickness limit. The applicable rolling procedures are defined as follows. 7.1 As Rolled – AR (2005) This procedure involves the rolling of steel at high temperature followed by air cooling. The rolling and finishing temperatures are typically in the austenite recrystallization region and above the normalizing temperature. The strength and toughness properties of steel produced by this process are generally less than steel heat treated after rolling or than steel produced by advanced processes. 7.3 Heat Treatment (1995) 7.3.1 Normalizing Heat Treatment (2005) A normalizing heat treatment is to consist of heating plates, wide flats, bars or shapes from an appropriate temperature below the transformation range to the proper temperature above the transformation range, holding for a sufficient time to effect the desired transformation and then individually cooling the material in air. The process improves the mechanical properties of as-rolled steel by refining the austenitic grain size, provided that the steel is produced to fine austenitic grain size practice. Normalizing heat treatments are usually conducted at the steel manufacturer’s plant. Such heat treatment may be carried out at a shipyard or fabricator’s plant, provided the Surveyor is satisfied with the heat-treating facilities and procedures. In such cases, the shipyard or fabricator is to indicate on the purchase order that the mill tests are to be made on normalized coupons. Otherwise, tests on the normalized material will be required at the shipyard or fabricator’s plant. 7.3.2 Special Heat Treatment Other types of heat treatment are to be specially approved. Part 2 Rules for Materials and Welding Chapter 1 Materials for Hull Construction Section 2 Ordinary-strength Hull Structural Steel 2-1-2 ABS RULES FOR TESTING AND CERTIFICATION OF MATERIALS . 2007 23 7.5 Controlled Manufacturing Process (1995) 7.5.1 Controlled Rolling – CR (Normalized Rolling – NR) (2005) Controlled rolling is a procedure in which the final rolling temperature is generally controlled within the range used for normalizing heat treatments so that the austenite completely recrystallizes, resulting in a material condition generally equivalent to that obtained by normalizing. 7.5.2 Thermo-mechanical Rolling – TM (Thermo-mechanical Controlled Processing – TMCP) (2005) Thermo-mechanical controlled processing involves the strict control of the steel temperature and the rolling reduction. Generally, a high proportion of the rolling reduction is carried out close to or below the Ar3 transformation temperature and may involve rolling toward the lower end of the temperature range of the intercritical duplex phase region, thus permitting little if any recrystallization of the austenite. Unlike controlled rolling, the properties produced by TM (TMCP) cannot be reproduced by subsequent normalizing or other heat treatment. The use of accelerated cooling on completion of rolling may also be accepted, subject to the special approval of the Bureau. Accelerated cooling (AcC) is a process which aims to improve mechanical properties by controlled cooling with rates higher than air cooling immediately after the final TM (TMCP) operation. Direct quenching is excluded from accelerated cooling. Where CR and TM with/without AcC are applied, the programmed rolling schedules are to be verified by the Bureau at the time of the steel works approval, and are to be made available when required by the attending Surveyor. On the manufacturer’s responsibility, the programmed rolling schedules are to be adhered to during the rolling operation. Refer to 2-1-1/1.2.2. To this effect, the actual rolling records are to be reviewed by the manufacturer and occasionally by the Surveyor. When deviation from the programmed rolling schedules or normalizing or quenching and tempering procedures occurs, the manufacturer shall take the further measures required in 2-1-1/1.2.2 to the Surveyor’s satisfaction. 7.7 Quenching and Tempering – QT (2005) Quenching involves a heat treatment process in which steel is heated to an appropriate temperature above the Ac3 and then cooled with an appropriate coolant for the purpose of hardening the microstructure. Tempering subsequent to quenching is a process in which the steel is reheated to an appropriate temperature not higher than the Ac1 to restore toughness properties by improving the microstructure. 9 Tensile Properties 9.1 Required Tensile Properties The material, except as specified in 2-1-2/9.5, is to conform to the requirements of 2-1-2/Table 2 as to tensile properties. Part 2 Rules for Materials and Welding Chapter 1 Materials for Hull Construction Section 2 Ordinary-strength Hull Structural Steel 2-1-2 24 ABS RULES FOR TESTING AND CERTIFICATION OF MATERIALS . 2007 9.3 Tension Test Specimens One tension test is to be made on two different plates, shapes or bars from each heat of steel, unless the finished material from a heat is less than 50 tons, when one tension test will be sufficient. If, however, material from one heat differs 9.5 mm (0.375 in.) or more in thickness or diameter, one tension test is to be made from both the thickest and the thinnest material rolled, regardless of the weight represented. One tension test is to be made on each plate as quenched and tempered. For plates from coils, tension tests are to be made from not less than two coils from each heat, except where a single coil is to be certified in which case tension test specimens from that coil only need be tested. Two tension tests are to be made from each coil tested. One tension test specimen is to be obtained from a location immediately prior to the first plate produced and a second test specimen obtained from the approximate center lap. When the coiled material from one heat differs by 1.6 mm (1/16 in.) or more in thickness, test specimens are to be obtained from both the thinnest and the thickest material rolled. 9.5 Exceptions Shapes less than 645 mm2 (1 in2) in cross section and bars, other than flats, less than 12.5 mm (1/2 in.) in thickness or diameter need not be subject to tension test, but chemistry consistent with the required tensile properties is to be applied. 9.7 (2007) 9.9 Omission of Elongation Requirements For raised-pattern floor plates not exceeding 12.5 mm (0.50 in.) in thickness, the requirement for elongation is waived. 9.11 Retests (1996) Where the results of the tension test do not comply with the requirements, two further tests may be carried out on specimens taken from the same sample. For elongation retest, 2-1-1/9.5 is to be complied with. For plates from coils, the retest specimens are to be taken adjacent to the original specimen. If the results of both additional tests meet the requirements, the material tested or represented by the test may be accepted. When the results of one or both additional tests do not meet the requirements, the sample is to be rejected unless the manufacturer elects to resubmit it after heat treatment or reheat treatment, or as another grade. The rest of the material represented by the test may be treated under 2-1-2/9.13. 9.13 Unsatisfactory Tests (1996) Where the tests under 2-1-2/9.3 and 2-1-2/9.13 fail, the remaining material from the same heat may be accepted, provided satisfactory results are obtained on both of two additional plates, shapes or bars selected in accordance with 2-1-2/9.3. When the results of one or both samples do not meet the requirements, all materials represented by the tests are to be rejected unless the manufacturer elects to submit each piece individually, or to resubmit the lot after heat treatment or reheat treatment or as another grade. aela Highlight aela Highlight aela Highlight aela Highlight aela Highlight Part 2 Rules for Materials and Welding Chapter 1 Materials for Hull Construction Section 2 Ordinary-strength Hull Structural Steel 2-1-2 ABS RULES FOR TESTING AND CERTIFICATION OF MATERIALS . 2007 25 11 Impact Properties 11.1 Impact Tests (1996) Charpy V-notch impact tests are to be carried out in accordance with 2-1-2/Table 4. These same requirements apply for flats, rounds and shapes when specially ordered in these grades unless agreed otherwise. For rolled sections, impact tests specimens are to be taken from the flanges of beams, channels and tees, and from the legs of angles and bulb angles. One set of three impact specimens is to be obtained from the thickest material rolled, except when the maximum thickness or diameter of the material represented by the test differs by 9.5 mm (0.375 in.) or more, in which case, one set of impacts is to be made from both the thickest and the thinnest material represented, regardless of their weight. See 2-1-1/11.11. For plates produced from coils, impact test coupons are to be obtained adjacent to both tension test coupons and a third impact test coupon is to be obtained immediately after the last plate produced to the qualifying grade or specification; in no case, however, is the frequency of impact testing to be less than that given above for plates, and where additional testing is required, three sets of specimens are to be obtained from each coil tested. 11.3 Impact Test Frequency The frequency of impact testing is to be in accordance with 2-1-2/Table 5. 11.5 Initial Test Requirements The average value of three specimens is to comply with the required average value in the Tables. Only one individual value may be below the required average and it is not to be less than 70% of the required average. Where the subsize specimens in 2-1-1/Figure 2 are to be used, the modified energy values will apply, as follows: Subsize Specimen Impact Requirements Specimen Size 10 × 7.5 mm 10 × 5.0 mm 10 × 2.5 mm (0.394 × 0.295 in.) (0.394 × 0.197 in.) (0.394 × 0.098 in.) Required Energy 5E/6 2E/3 E/2 E = energy required for 10 × 10 mm (0.394 × 0.394 in.) specimen 11.7 Retests When the results fail to meet the above requirements but conditions ii) and iii) below are complied with, three additional specimens may be taken from the location as close to the initial specimens as possible and their test results added to those previously obtained to form a new average. The material represented may be accepted if for the six specimens all of the following conditions are met: i) The average is not less than the required average. ii) No more than two individual values are below the required average. iii) No more than one individual value is below 70% of the required average. If the results of tests do not meet the above requirements, the material tested is to be rejected unless the manufacturer elects to resubmit it after heat treatment or reheat treatment, or to resubmit as another grade. Part 2 Rules for Materials and Welding Chapter 1 Materials for Hull Construction Section 2 Ordinary-strength Hull Structural Steel 2-1-2 26 ABS RULES FOR TESTING AND CERTIFICATION OF MATERIALS . 2007 11.9 Unsatisfactory Tests The remaining material from the heat may be accepted, provided satisfactory impact results are obtained on both of two further plates of the same thickness as the rejected plate in the heat. Alternatively, the manufacturer may qualify material of the same thickness by impact testing each plate. Plates of a lesser thickness in the same heat may be accepted, provided that satisfactory results are obtained on impact specimens taken from the next lower thickness than the rejected plate. 11.11 Thin Plates (1996) Generally, impact tests are not required for plates less than 6 mm (0.24 in.) in thickness. 13 Marking 13.1 Stamped or Stenciled Material The Bureau markings AB and the applicable grades listed in 2-1-2/Table 1 indicating satisfactory compliance with the Rules are to be clearly steel-die-stamped or stenciled by the manufacturer on each finished plate, shape and bar to signify that the material has satisfactorily complied with the tests prescribed and that certificates for the material will be furnished to the Surveyor in accordance with 2-1-1/7. Coiled steel which is certified for chemical analysis only, is to be marked AB without the grade designation. 13.3 Coils, Lifts and Bundles In special cases, upon application, coils intended for light plate and secured lifts or bundles of light plates, shapes or bars of comparatively small size may be steel-die stamped, stenciled, or labeled on only the top piece or at another approved location, or the markings may be shown on a tag attached to each coil, lift or bundle. 13.5 Flanging-quality Identification All material intended for cold flanging, when specially approved in accordance with 3-1-2/1.1, is to be additionally marked F to signify that it is of such quality. 13.7 Special Stamping and Marking Material, other than those grades listed in 2-1-2/Table 1, is to be marked with both the initials AB/S and with either the applicable specification number, or such other markings as may be required for ready identification, to signify that the material has been produced and satisfactorily tested in accordance with the specification. When a specification does not specifically require normalizing but the material is so ordered and so produced, then the plates are also to be marked with the initial N to indicate that the material has been normalized. A shipyard or fabricator who carries out a normalizing heat treatment in accordance with 2-1-2/7 is to also mark such material with the initial N. 13.9 Special Impact Testing When steel is impact tested at temperatures other than those specified in 2-1-2/Table 4, the grade marking is to be followed by the test temperature in degrees Celsius. A prefix ‘‘O’’ to the test temperature is to indicate a temperature colder than zero degrees Celsius. 13.11 Steel with Improved Through Thickness Properties Steel plates meeting the requirements of 2-1-1/17 are to have the letter Z marked after the grade designation. Part 2 Rules for Materials and Welding Chapter 1 Materials for Hull Construction Section 2 Ordinary-strength Hull Structural Steel 2-1-2 ABS RULES FOR TESTING AND CERTIFICATION OF MATERIALS . 2007 27 13.13 Steel with Ultrasonic Examination Steels meeting the requirements of 2-1-1/21 are to have the letter U marked after the grade designation as a final letter. 13.15 Shipping Procedure No material bearing these markings is to be forwarded from the steel works until the prescribed tests have been satisfactorily carried out in accordance with the Rules. 13.17 Steel at Secondary Sources Secondary sources for ABS Grade Steel are required to assure traceability of steel intended for Bureau certification. To retain proper identification, steel may be marked with the information indicated by the manufacturer’s markings to the satisfaction of the Surveyor. 15 Surface Finish 15.1 Surface Inspection The material will be surface inspected by the Surveyor when specially requested by the purchaser. It is to be free from defects and have a workmanlike finish subject to the conditions given in the following subparagraphs. 15.3 Treatment of Surface Defects – Plates Plates may be conditioned by the manufacturer for the removal of surface defects on either surface by grinding, provided each ground area is well faired and the grinding does not reduce the thickness of the plate i) More than 7% under the nominal thickness and in no case more than 3.2 mm (0.125 in.) when ordered to weight or; ii) Below the minimum thickness permissible under 2-1-1/15.3 when ordered to thickness. Plates may have surface defects removed by chipping, grinding or gouging and then depositing weld metal, subject to the following limiting conditions. 15.3.1 Extent of Weld Repaired Area The total weld repaired area of each surface of a plate is not to exceed 2% of the area of that surface. 15.3.2 Minimum Thickness Before Weld Repairs After removal of any defect preparatory to welding, the thickness of the plate is not to be reduced by more than 20% of the nominal thickness. 15.3.3 Inspection Before Weld Repairs An experienced mill inspector is to examine the work to see that the defects have been removed completely and that the foregoing limitations have not been exceeded. The Surveyor is to be given full opportunity to make this same inspection. To assure removal of defects, magnetic particle or liquid penetrant examination may be required. Part 2 Rules for Materials and Welding Chapter 1 Materials for Hull Construction Section 2 Ordinary-strength Hull Structural Steel 2-1-2 28 ABS