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DNV-OS-B101 Metallic Materials |
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| Ch.2: Technical Provisions |
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| Sec.1: Rolled Steel for Structural Application |
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| E: Testing |
| — | Plates
and wide flats with a width ³ 600 mm The test material shall be taken at the square cut end approximately one-quarter width from an edge, see Fig. 1a. |
| — | Flats with a width < 600
mm, bulb flats and other sections The test material shall be taken at approximately one-third of the width from an edge, see Figures 1b, 1c, 1d and 1e. For channels and beams, an alternative position is shown in Fig. 1d. |
| — | Bars and other similar products The test material shall be taken at a depth one-third of the radius below the surface or, in the case of non-cylindrical sections, at a depth one-third of the half-diagonal from the surface, see Fig. 1f. |
Longitudinal: longitudinal axis of test piece parallel to the principal direction of rolling.
Transverse: longitudinal
axis of test piece perpendicular to the principal direction of rolling.
Ch.2 Sec.1 E
105 Unless otherwise agreed,
the test pieces shall be oriented as follows:
| — | Plates
and wide flats with a width ³ 600 mm Tensile test pieces shall be transverse. Impact test pieces shall be longitudinal, except that for extra high strength steel, transverse tests are required. |
| — | Flats with a width < 600
mm, bulb flats and other sections Tensile and impact test pieces shall be longitudinal. |
| — | Bars and other similar products Tensile and impact test pieces shall be longitudinal. |
The notch shall be cut in a face of the test pieces which
was originally perpendicular to the rolled surface. The position
of the notch shall not be nearer than 25 mm to a flame cut or sheared
edge.
Ch.2 Sec.1 E
302 For thicknesses equal to or below 50 mm, the impact test pieces
shall be taken not less than 2 mm below the surface. For plate thicknesses
exceeding 50 mm, impact test pieces shall be situated so that the
distance between the centre-line of the test piece and the plate
surface is not less than 1/4 of the plate thickness.
Ch.2 Sec.1 E
303 Where it is impossible to use a standard impact test piece of
10 mm ´ 10 mm, the largest possible of the following pieces shall
be used: 10 mm ´ 7.5 mm or 10 mm ´ 5 mm. The required impact
values are then reduced to respectively 5/6 and 2/3
of the required values of the standard test piece.
Ch.2 Sec.1 E
304 The average energy value from each set of three impact tests
and the single values shall comply with the appropriate requirements
of Table B4, Table
C5, and Table D3 for steel grades
of normal weldability. For steel grades of improved weldability,
requirements are given in Table B2, Table C2 and Table
D2 as appropriate. Further, only one individual value within
each set may be below the specified minimum average value, but not
lower than 70% of this value.
Scope
Ch.2 Sec.1 E
401 These requirements are supplementary to A to D and apply to
plates and wide flats with thickness 15 mm and over with improved
through thickness or 'Z' direction properties, see
Fig.2. The use of 'Z' grade steels is recommended
for certain types of welded structures where plates are subjected
to significant strains in the through thickness direction in order
to minimise the possibility of lamellar tearing during fabrication.
Ch.2 Sec.1 E
402 Provision is made for two quality classes Z25 and Z35 based
on specified minimum values for reduction of area in a through thickness
tensile test. Quality class Z25 is intended for normal ship applications
and Z35 for more severe applica-tions.
Fig. 1 Through thickness tensile testing
Manufacture
Ch.2 Sec.1 E
403 It is recommended that
special steelmaking processes and techniques such as vacuum degassing,
sulphide shape control or suitable low sulphur techniques are used.
Chemical composition
Ch.2 Sec.1 E
404 The steel grades shall
be killed and fine grain treated. The maximum sulphur content shall
be 0.008% unless alternative methods of improving through
thickness properties have been agreed to.
Test material
Ch.2 Sec.1 E
405 Test material shall be
taken close to the longitudinal centreline from one end of each
rolled piece representing the test unit, see Fig.3 and Table E1.
Ch.2 Sec.1 E
406 The test material must
be large enough to accommodate the preparation of six test pieces.
Three test pieces shall be prepared while the rest of the sample
remains for possible retest.
Ch.2 Sec.1 E
407 Round test pieces shall
be prepared in accordance with recognised standards, e.g. EN 10164
and ASTM A770.
Fig. 2 Plate and wide flat sampling position
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Fig. 3 Position of test specimen | |
Ch.2 Sec.1 E
| Table E1 Test unit
(batch) size dependent on product and sulphur content | |||||||||||
| Product | S > 0.005% | S £ 0.005% | Plates | Each piece | (parent plate) Maximum 50 t of products of the same
heat, thickness and condition of supply | Wide flats of nominal thickness £ 25
mm | Maximum 10 t of products of the same heat,
thickness and condition of supply | Maximum 50 t of products of the same
heat, thickness and condition of supply | Wide flats of nominal thickness | > 25 mm Maximum 20 t of products of the same heat,
thickness and condition of supply | Maximum 50 t of products of the same
heat, thickness and condition of supply | |
Mechanical testing
Ch.2 Sec.1 E
408 The average reduction
of area value of three test pieces shall be determined and meet
the specified minimum average value given in Table E2. One individual
value may be below the specified minimum average value, provided
that it is not less than the specified minimum individual value.
Ch.2 Sec.1 E
409 If the results do not
meet the specified requirements, three additional test pieces from
the same sample may be tested. The test unit will then be accepted
provided that the following conditions are met:
| — | the average value of six test pieces meets the specified minimum average value |
| — | not more than two of six individual values are lower than the specified minimum average value |
| — | not more than one of six individual values is lower than the specified minimum individual value. |
Ch.2 Sec.1 E
| Table E2 Reduction of Area Acceptance Values | ||||||||
| Quality class | Z25 | Z35 | Minimum average | 25% | 35% | Minimum individual | 15% | 25% | |
Ultrasonic testing
Ch.2 Sec.1 E
412 All products shall be
submitted to ultrasonic testing in the condition of supply with
a probe frequency of 3-5 MHz. Testing shall be performed in accordance
with EN 10160 Level S1/E1 or ASTM A578 Level C.
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