CHAPTER 2 CRHS-56/70 STEEL PLATE, SHEET, OR COIL
2.9 Tests and Examinations
Examinations of surface quality, dimensions and internal soundness are the responsibility of the steel the Manufacturer.
The acceptance by the Surveyor of the Society is not to absolve the steel the Manufacturer from this responsibility.
2.9.1 Chemical composition
(a) Specimens shall be analyzed in accordance with a standard ASTM method or a method that will ens ure equally accurate results for conformance to the chemical composition requirements. The method(s) shall be correlated with National Institute of Standards and Technology standard reference materials, when available, to ensure the validity of the test method that is used as a control in chemical analysis or for calibration in instrumental methods of analysis. Additionally, the range over which the chemical analysis test methods can be shown to be accurate for the particular element reported shall be provided. The accuracy and precision of the chemical analysis method(s) used for each element being analyzed shall be provided.
(b) If the samples from the inspected plate, sheet, or coil fail to meet the requirements, all material from the lot in question shall be rejected. Samples from rejected lots of plates, sheets, or coils may be analyzed individually provided the samples are taken from each in the specified locations, and only those plates, sheets, or coils which conform to chemical composition requirements will be accepted.
2.9.2 Microstructure analysis
(a) Prior Austenite grain size
For works approval, the average prior austenite grain size shall be determined in accordance with the planimetric procedure of ASTM E112 for the product in the final heat treated condition.
(b) Microstructure
The microstructure at the centerline of the thickest plate to be qualified shall be reported in the form of photomicrographs showing the relative quantities and morphologies of the phases present.
2.9.3 Mechanical tests
(a) Tensile test
Tensile test specimens shall be tested in accordance with ASTM A370 and, for through-thickness testing of plate when required, ASTM A770. If a product is to be aged or otherwise heat treated to reduce hydrogen, then the tensile test specimen(s) shall be removed from the plate, prolongation, or keel block after the
CHAPTER 2 CRHS-56/70 STEEL PLATE, SHEET, OR COIL 2.9 Tests and Examinations
(b) Impact toughness
(i) Charpy V-notch impact test
Production lot verification test specimens shall be tested in accordance with ASTM A370 with coolant temperatures as specified in Table 2-6. For works approval testing, Charpy V-notch transition curves (transverse to rolling direction) with data points at each temperature of minus 84 °C, minus 68 °C, minus 51 °C, minus 34 °C, minus 18 °C, and room temperature shall be provided. At least three specimens for each point are required and individual values shall be recorded.
(ii) Drop weight nil-ductility test
For works approval, the test specimen shall be tested in accordance with ASTM E208. The specimen shall exhibit "no break" condition at minus 68±2 °C for CRHS-56 and at the temperature specified in purchase order for CRHS-70.
(iii) Marking of Test Specimens
The test specimens shall be marked to ensure positive identification of the lot being tested.
(c) CTOD test
(i) The crack tip opening displacement (CTOD) tests for metallic materials and weldments shall be carried out according to BS 7448 Parts 1 & 2, or ASTM E1820, or any other recognized standard.
(ii) The CTOD test specimens are to be tested in three point bending. Specimen dimension shall be in accordance with BS 7448 Parts 1 & 2, or ASTM E1820, or any other recognized standard.
(iii) The CTOD test is to use a testing machine with controllable loading rate and displacement -load synchronous recording device, and the data of test process are to be recorded automatically. The test equipment is to be calibrated annually.
(iv) The crack opening displacement gauge is to have an accuracy of at least one per cent. It is to be calibrated at least once every day of testing and at intervals of no more than 10 tests. It should be demonstrated that the calibration is satisfactory for the test conditions.
2.9.4 Weldability tests
(a) General
Weldability tests are required for plates and are to be carried out on samples of the thickest plate.
(b) Preparation and welding of the test assemblies
The welding procedure should be as far as possible in accordance with the normal welding practice used at the yards for the type of steel in question.
The welding parameters including consumables designation and diameter, pre -heating temperatures, interpass temperatures, heat input, number of passes, etc. are to be reported.
(c) Type of tests
From the test assemblies the following test specimens are to be taken:
(i) Tensile test
(ii) Charpy V-notch impact test.
The fusion boundary is to be identified by etching the specimens with a suitable reagent. The test temperature is to be the one prescribed for the testing of the steel grade in question.
(iii) Hardness tests HV 5 across the weldment.
The indentations are to be made along a 1 mm transverse line beneath the plate surface on both the face side and the root side of the weld as follows:
- Fusion line
- HAZ: at each 0.7 mm from fusion line into unaffected base material (6 to 7 minimum measurements for each HAZ)
The maximum hardness value should not be higher than 350 HV.
A sketch of the weld joint depicting groove dimensions, number of passes, hardness indentations should be attached to the test report together with photomacrographs of the weld cross section.
2.9.5 Surface quality
(a) Visual examination
Each plate shall be examined visually and shall meet the requirements of surface quality. With respect to coating applications, the number of plates subject to paint film thickness measurements should be held to the minimum necessary to assure continued satisfactory performance.
(i) Procedures of coating
The material, as prepared for coating, shall be in the descaled condition and free from visible rust. Plates, sheets, or coils shall be cleaned by either abrasive blast cleaning or acid pickling. One coat of primer shall be applied to a dry film thickness of approximately 0.025 mm. The drying time of the coating at 23 °C shall be a maximum of 6 hours. The thickness of the dry film shall be not less than 0.018 mm at any point. The Manufacturer shall choose a coating compatible with the intended application and duration of protection.
(ii) Descale
(1) Abrasive blast cleaning
Abrasive blast cleaning shall result in a clean metal surface for painting, with mill scale, rust, and other surface contaminants completely removed.
(2) Acid pickling
The acid pickling process shall be as follows:
- Plates, sheets, or coils shall be handled on edge throughout the various steps of the procedures. They shall not be laid flat in the solutions.
- Rust preventatives, oils, greases, oil paints, and other foreign matter shall be removed from the plates prior to immersion in the acid pickling bath. Where alkaline solutions are used for this purpose, the plates shall be thoroughly rinsed with water prior to pickling.
- The pickling bath shall consist of a sulphuric acid solution to which has been added pickling inhibitor and 1.5% of sodium chloride. In making the solution initially, 19 liters of concentrated sulphuric acid are used for each 378.5 liters of solution. The acid concentration shall not be allowed to drop below 3.5% by volume. The inhibitor shall be used at the concentration recommended by the Manufacturer. The bath temperature shall be maintained at 71 to 82 °C. When the concentration of iron in the solution reaches 5%
by weight, the entire bath shall be discarded.
- The water rinse shall consist of fresh circulating water maintained at a temperature of 49 to 82 °C. The flow of fresh water shall be maintained so that a complete change of water occurs every 24 hours. The combined concentrations of sulphuric acid and iron sulfates in the bath, calculated from the acid concentration and the ferrous iron concentration, shall not exceed 5.3 grams per 10 liters. This determination shall be made at least once each week.
(iii) Measurement of coating
The paint film shall cover surface roughness peaks. Two random dry film thickness measurements per 9 m2 of painted surface, made with a calibrated suitable thickness gauge, shall be sufficient for determining conformity of any one plate to the specified coating thicknesses.
Other methods of measurement may be used for paint film thickness, subject to the approval of the Society. Organic coatings containing lead, chromium, asbestos, arsenic, or mercury shall not
CHAPTER 2 CRHS-56/70 STEEL PLATE, SHEET, OR COIL 2.9 Tests and Examinations
(b) The depth of rolled-in scale, pits, or other defects shall not exceed 0.38 mm and shall not result in an under gauge (less than minimum thickness) condition. Isolated, individual pits not over 0.76 mm deep or within 152 mm of each other will be acceptable, provided plate, sheet, or coil thickness is not reduced to an under gauge condition. Surface imperfections may be removed by grinding, provided the thickness is not reduced to an under gauge condition and the ground area is smoothly faired into surrounding metal.
(i) Weld repair of mill defects after heat treatment
Unless otherwise specified in purchase order, weld repair after final heat treatment shall be permitted.
Mill imperfections may be repair-welded by the Manufacturer or referred to the contracting activity for acceptance with subsequent repair welding to be performed by the contracting activity. Areas of the plate, sheet, and coil found to have less than the minimum specified thickness may have the thickness restored by welding the depressed area. The following limitations shall apply to all weld repairs:
(1) The total area to be repaired shall not exceed 1% of the surface of one side of the plate, sheet, or coil.
(2) The depth of any area to be repaired shall not exceed one-half the minimum plate or coil thickness specified or 13 mm, whichever is less. The depth of the area to be repaired shall be a minimum of 1.6 mm.
(3) Areas within 51 mm of each other which require weld repair shall be combined to form a single repair.
(4) Areas to be welded shall be ground to assure that the welds are made on clean, sound metal.
(5) After preparation for repair and prior to welding, the depressed area shall be magnetic particle inspected in accordance with NAVSEA Technical Publication T9074-AS-GIB-010/271, and shall be free of relevant linear indications.
(6) Weld repairs shall be made in accordance with NAVSEA Technical Publication T9074-AD-GIB-010/1688, MIL-STD-1689, or the applicable fabrication document. Procedures and personnel shall be qualified in accordance with NAVSEA Technical Publication S9074 -AQ-GIB-010/248.
(7) The final repaired surface shall be ground smooth and shall be essentially flush with the adjacent surface and free of undercut in excess of 0.5 mm. No point of the finished weld surface shall be below the adjacent plate surface.
(8) Surface weld repairs shall be magnetic particle inspected after final grinding (or subsequent heat treatment, if applicable) in accordance with NAVSEA Technical Publication T9074 -AS-GIB-010/271. Welds and 13 mm of adjacent base material shall be free of relevant linear indications greater than 3.2 mm in length.
(9) Repaired areas shall be marked. The markings shall remain legible and shall not be removed prior to performing all inspections specified herein.
(10) Notation of such repaired areas and the type of welding material used to make the weld repair(s) shall be made on the plate inspection form as part of the records.
(11) If a non-heat treatable electrode is used, reheat treatment of the plate, sheet, or coil is prohibited.
(12) MIL-120S-1 and MIL-12018-M2 or equivalent strength welding consumables shall not be used for any welding including repair welding and weld build-up.
(13) MIL-11018-M electrodes shall not be used for any welding including repair welding and weld build-up. Weld repair and weld build-up shall be accomplished using 10718-M or MIL-100S electrodes.
(ii) Weld repairs of mill defects prior to heat treatment
Weld repairs of mill imperfections may be accomplished prior to heat treatment within the limitations as specified in 2.9.5(b)(i), except such weld repairs shall be made using a heat treatable electrode approved by the Society.
(iii) Edge defects
Visual laminar edge defects less than 6.4 mm long shall be acceptable. Laminar edge defects 6.4 mm long and over shall be explored by ultrasonic inspection on the surface adjacent to the affected area.
Edge defects that extend into the material that will result in rejectable defects according to the ultrasonic
acceptance standards specified in 2.9.2 shall be cause for rejection. Laminar edge defect weld repairs shall be made using a weld procedure approved by the Society.
2.9.6 Dimensional tolerances
Tolerances shall be as specified in (a) through (f):
(a) Tolerances for material less than 4.8 mm in thickness
For material less than 4.8 mm in thickness, the tolerances of ASTM A505 shall apply.
(b) Alternate dimensional tolerances
Due to extensive past applications of CRHS-56/70 plate to the tolerances of ASTM A6, when specified in purchase order, CRHS-56/70 plate shall be ordered to the tolerances specified in ASTM A6. When plate is ordered to the dimensional tolerances in ASTM A6 and ordered by weight, the allowable under gauge at the edge of plates shall be as specified in Table 2-7.
(c) Thickness, weight, and gauge
For plate ordered to decimal thickness over 4.8 mm and not ordered to ASTM A6, the maximum allowable variations in thickness measurements shall be as specified in Table 2-8 and Table 2-9. For plate ordered to a specific weight basis and not ordered to ASTM A6, the maximum allowable variations in weight and gauge shall be as specified in Table 2-7.
(d) Flatness
Plates over 4.8 mm thick not ordered to ASTM A6 shall be flat within the tolerance limits specified in Table 2-10. The flatness, as specified in Table 2-10, shall be an overall flatness factor. This factor shall not apply to "kinks" or "waviness". The waviness or kinking permitted shall be judged by laying a 1-meter straightedge across the affected edges. The maximum permissible deviation from the straightedge shall be 6.4 mm. When specified purchase order, tighter requirements may be required.
(e) Camber
Camber of the plates over 4.8 mm thick not ordered to ASTM A6 shall not exceed the tolerance limits specified in Table 2-11.
(f) Size tolerances
The width and length of the plates over 4.8 mm thick not ordered to ASTM A6 shall not vary in excess of the tolerances specified in Table 2-12 and Table 2-13.
2.9.7 Internal soundness and thickness
Plates over 13 mm thick, unless otherwise specified in purchase order, shall be ultrasonically inspected for internal soundness in accordance with 2.9.7(a)(i) and ultrasonically measured for decimal thickness in accordance with 2.9.7(a)(ii). Each Type II plate, and, when specified in purchase order, all plates, shall be ultrasonically inspected for internal soundness and ultrasonically measured for decimal thickness. Plates over 13 mm thick not ultrasonically inspected or ultrasonically measured for decimal thickness shall be classified as Type I in accordance with 2.5.1.
(a) Ultrasonic examination
The requirements of NAVSEA Technical Publication T9074-AS-GIB-010/271 shall apply for the qualification of ultrasonic testing personnel, qualification and calibration of equipment, qualification of
CHAPTER 2 CRHS-56/70 STEEL PLATE, SHEET, OR COIL 2.9 Tests and Examinations
Examinations shall be performed in accordance with ASTM A435, including the Supplementary Requirements of S1, and shall meet the acceptance standards stated therein.
(ii) Ultrasonic thickness
Examinations shall be performed and meet the requirements of Table 2-8 and Table 2-9 herein. When plate is specified on a lb/ft2 basis, ultrasonic inspection for thickness is not required.
(b) Documentation
(i) Records of thickness measurements and soundness specified in 2.9.6(b)(ii) shall be prepared and transmitted with the material
(ii) When internal soundness inspection is performed, results shall be prepared in accordance with the format shown on Fig. 2-7.
2.9.8 Explosion test
For works approval, the explosion crack starter test and explosion bulge test shall be conducted in accordance with Appendix 1.
2.9.9 Rejection and retests
(a) When a test specimen representing a lot of material fails to meet specification requirements, the lot sh all be rejected. The Manufacturer may rework or retest the lot as provided herein. The Manufacturer shall identify and separate rejected lots from acceptable lots until the rejected lots are withdrawn by the Manufacturer, or are demonstrated as meeting specification requirements.
(b) Only one (1) retest of a nonconforming original test is permitted, and the retest specimens shall be taken in the vicinity of the initial location of the failed specimen(s). If any retest specimen fails, the lot shall be rejected with no further testing permitted, except in cases where a lot consists of more than one item.
When a lot with a rejected test specimen consists of more than one item and there are no other instructions specified in this chapter, at the option of the Manufacturer, each item in the rejected lot may be tested for the failed test and each item that fails to meet the requirements shall be rejected.
All test results, including failures, shall be reported, unless otherwise approved by the Society in works approval to accommodate automated data reporting systems. In all cases, all test results, including failures, shall be available for review upon request.
(i) Reheat treatment
The Manufacturer shall be permitted to reheat-treat material along with the representative prolongations or test blocks which fail to meet the tensile or impact requirements. Required tests at the same required test location as originally performed on the failed material shall be repeated when the material is re-inspected, except for the chemical analysis. On any additional heat treatment given, including austenitizing/quench and temper/quench, re-tempering/quench or hydrogen soak, all the new mechanical test specimens from the material, prolongation, or test block shall be taken from locations that meet the criteria from as quenched surfaces of the reheat treatment as specified in this chapter.
(ii) Tensile retest
If the results of an original tensile specimen fails to meet the requirements, but are within 6.9 MPa of the required yield strength, or within 2 percent of the required elongation, or within 2 percent of the required reduction-in-area, a retest on two additional specimens (selected from the same approximate location) shall be permitted.
- Gauge Length Retest
If the percentage of elongation or reduction in area of an individual tensile specimen is less than that prescribed in this chapter, and any part of the fracture is outside the gauge length, or within the gauge
length and less than 25 percent of the gauge length from either datum point, another specimen from the same approximate location may be selected in its place.
(iii) Charpy V-notch retest
In the event that initial Charpy V-notch test results at a specified temperature do not meet the requirements, a retest of two additional sets of specimens (i.e., six specimens) from the same approximate location and at the same temperature shall be permitted on the same material. If the retest specimens do not meet the requirements (average and individual values), the lot represented by the specimens shall be rejected.
(d) Defective specimen/replacement of test specimens
A test specimen shall be discarded and a replacement specimen selected from the same lot of the material under the following conditions:
(i) When the specimen is incorrectly machined.
(ii) When the test procedure is incorrect.
(iii) When there is a malfunction of the testing equipment.
(iv) When a flaw that is not indicative of an inferior or defective lot of material is revealed during the test.
However, internal flaws such as cracks, ruptures, and porosity are not reasons for the selection of a replacement test specimen.