GB/T 37602-2019Ship and offshore engineering steel for low temperature service (English PDF)

3.1

The steel grade, thickness direction (Z direction) performance level and classification shall meet the requirements of Table 1.

Table 1 Steel grades, thickness direction (Z direction) performance levels and classification

Grade thickness direction (Z direction) grade classification

LT32-1, LT32-2, LT32-3

LT36-1, LT36-2, LT36-3

LT40-1, LT40-2, LT40-3

Z25, Z35 carbon-manganese low temperature steel

0.5NiA, 0.5NiB, 1.5Ni, 2.25Ni

3.5Ni, 5Ni, 9Ni

Z25, Z35 nickel series low temperature steel 3.2 The grade of carbon-manganese low-temperature steel consists of the first letter LT representing the English lowtemperature of low temperature, the specified yield strength level, and the low-temperature toughness.

Sex level (1, 2 and 3) consists of 3 parts. The grade of nickel-based low temperature steel consists of the average content of nickel and the symbol of chemical element (Ni).

composition.

Example 1. LT32-2.

LT --- represents the first letter LT of English Lowtemperature;

32 --- represents the specified yield strength level;

2 --- represents low temperature toughness level.

Example 2. 3.5Ni.

Ni --- a chemical element symbol representing nickel.

3.3

When the purchaser requires the steel plate to have the thickness direction performance, add the representative thickness direction (Z direction) performance level after the grade specified in Table 1.

Symbol, for example. LT32-2-Z35.

5.1

The size, shape, weight and allowable deviation of the steel plate shall meet the requirements of GB/T 709.The deviation under the thickness of the steel plate is limited to -0.3mm, and

Should ensure that the average thickness of the steel plate is not less than the nominal thickness.

5.2

The size, shape, weight and allowable deviation of section steel shall meet the requirements of GB/T 706.

5.3

The density of 9Ni steel shall be implemented as 7.89g/cm3, and the density of other steel grades shall be implemented as 7.85g/cm3.

6.1 Grade and chemical composition

6.1.1

The grade and chemical composition (smelting analysis) of the steel shall meet the requirements in Table 2.

Table 2 Steel grades and chemical composition (smelting analysis)

Grade

Chemical composition a, b, c (mass fraction) /%

C Mn Si PS Ni other elements

LT32-1

LT32-2

LT36-1

LT36-2

LT40-1

LT40-2

<=0.18

LT32-3

LT36-3

LT40-3

<=0.16

0.70 ~ 1.60 0.10 ~ 0.50 <=0.025 <=0.025 <=0.80

Cu<=0.35

Cr<=0.25

Mo<=0.08

Nb<=0.05

V<=0.10

Als >= 0.015

N<=0.015

0.5NiA <=0.14 0.70 ~ 1.50 0.10 ~ 0.50 <=0.025 <=0.010 0.15 ~ 0.80

0.5NiB <=0.16 0.85 ~ 1.70 0.10 ~ 0.50 <=0.025 <=0.010 0.15 ~ 0.85

1.5Ni <=0.14 0.30 ~ 1.50 0.10 ~ 0.35 <=0.025 <=0.020 1.30 ~ 1.70

2.25Ni <=0.13 0.30 ~ 1.50 0.10 ~ 0.35 <=0.025 <=0.020 2.00 ~ 2.50

3.5Ni <=0.12 0.30 ~ 0.80 0.10 ~ 0.35 <=0.025 <=0.020 3.20 ~ 3.80

5Ni <=0.12 0.30 ~ 0.90 0.10 ~ 0.35 <=0.025 <=0.020 4.70 ~ 5.30

9Ni <=0.10 0.30 ~ 0.90 0.10 ~ 0.35 <=0.025 <=0.020 8.50 ~ 10.0

Cu<=0.35

Cr<=0.25

Mo<=0.08

Als >= 0.015

N<=0.012 a For 0.5NiA and 0.5NiB, Cr Mo Cu<=0.50%; for 1.5Ni ~ 9Ni, Cr Mo Cu<=0.60%.

b For 0.5NiA and 0.5NiB with a thickness of not less than 40mm, the lower limit of the Ni content is 0.30%.

c The content of acid-soluble aluminum (Als) can be replaced by the total aluminum (Alt) content. At this time, Alt should not be less than 0.020%.

6.1.2

According to the requirements of the acquirer, each grade can provide the smelting analysis carbon equivalent (Ceq), the value of which is to be determined by both parties. Carbon Equivalent (Ceq)

Equation (1) calculates.

Ceq = C Mn/6 (Cr Mo V)/5 (Ni Cu)/15 (1) 6.1.3 When the purchaser requires to guarantee the thickness direction performance of the steel sheet, the S content shall meet the requirements of GB/T 5313.

6.1.4

The allowable deviation of the chemical composition of the finished steel shall meet the requirements of GB/T 222.

6.2 Smelting method

Steel is smelted by converter or electric furnace and should be refined outside the furnace. All steels should be killed steel with aluminum deoxidation.

6.3 Delivery status

The delivery status of the steel shall meet the requirements in Table 3.

Table 3 Delivery status

Classification grade delivery status

Carbon-manganese low temperature steel

LT32-1, LT32-2, LT32-3

LT36-1, LT36-2, LT36-3

LT40-1, LT40-2, LT40-3

Controlled rolling, thermo mechanical rolling (TMCP), normalizing or quenching and tempering

Nickel low temperature steel

0.5NiA, 0.5NiB, 1.5Ni, 2.25Ni, 3.5Ni Thermomechanical rolling (TMCP), normalizing, normalizing or tempering

5Ni normalized, normalized or tempered

9Ni twice normalized or tempered

6.4 Mechanical properties

6.4.1

The mechanical properties of steel shall meet the requirements in Table 4.

Table 4 Mechanical properties

Grade

Stretching test

Upper yield strength

ReH/MPa not less than tensile strength

Rm/MPa

Elongation after breaking

A /% not less than

Charpy (V-notch) impact testa

Material thickness t/mm

Test temperature

T/°C

Impact absorption energy KV2/J

Portrait Landscape not less than

Minimum design

Temperature/°C

LT32-1 315 440 ~ 570 22

<=25 -20

> 25 ~ 30 -25

> 30 ~ 35 -30

> 35 ~ 40 -35

> 40 ~ 60 -40

41 27 -15

LT32-2 315 440 ~ 570 22

<=25 -40

> 25 ~ 30 -45

> 30 ~ 35 -50

> 35 ~ 40 -55

> 40 ~ 60 -60

41 27 -35

LT32-3 315 440 ~ 570 22

<=25 -60

> 25 ~ 30 -65

> 30 ~ 35 -70

> 35 ~ 40 -75

> 40 ~ 60 -80

41 27 -55

Table 4 (continued)

Grade

Stretching test

Upper yield strength

ReH/MPa not less than tensile strength

Rm/MPa

Elongation after breaking

A /% not less than

Charpy (V-notch) impact testa

Material thickness t/mm

Test temperature

T/°C

Impact absorption energy KV2/J

Portrait Landscape not less than

Minimum design

Temperature/°C

LT36-1 355 490 ~ 630 21

<=25 -20

> 25 ~ 30 -25

> 30 ~ 35 -30

> 35 ~ 40 -35

> 40 ~ 60 -40

41 27 -15

LT36-2 355 490 ~ 630 21

<=25 -40

> 25 ~ 30 -45

> 30 ~ 35 -50

> 35 ~ 40 -55

> 40 ~ 60 -60

41 27 -35

LT36-3 355 490 ~ 630 21

<=25 -60

> 25 ~ 30 -65

> 30 ~ 35 -70

> 35 ~ 40 -75

> 40 ~ 60 -80

41 27 -55

LT40-1 390 510 ~ 660 20

<=25 -20

> 25 ~ 30 -25

> 30 ~ 35 -30

> 35 ~ 40 -35

> 40 ~ 60 -40

41 27 -15

LT40-2 390 510 ~ 660 20

<=25 -40

> 25 ~ 30 -45

> 30 ~ 35 -50

> 35 ~ 40 -55

> 40 ~ 60 -60

41 27 -35

LT40-3 390 510 ~ 660 20

<=25 -60

> 25 ~ 30 -65

> 30 ~ 35 -70

> 35 ~ 40 -75

> 40 ~ 60 -80

41 27 -55

Table 4 (continued)

Grade

Stretching test

Upper yield strength

ReH/MPa not less than tensile strength

Rm/MPa

Elongation after breaking

A /% not less than

Charpy (V-notch) impact testa

Material thickness t/mm

Test temperature

T/°C

Impact absorption energy KV2/J

Portrait Landscape not less than

Minimum design

Temperature/°C

0.5NiA 285 420 ~ 530 24

<=25 -60

> 25 ~ 30 -65

> 30 ~ 35 -70

> 35 ~ 40 -75

> 40 ~ 60 -80

41 27 -55

0.5NiB 355 490 ~ 610 22

<=25 -60

> 25 ~ 30 -65

> 30 ~ 35 -70

> 35 ~ 40 -75

> 40 ~ 60 -80

41 27 -55

1.5Ni 275 470 ~ 640 22

<=25 -65

> 25 ~ 30 -70

> 30 ~ 35 -75

> 35 ~ 40 -80

> 40 ~ 60 -85

41 27 -60

2.25Ni 305 500 ~ 660 22

<=25 -70

> 25 ~ 30 -75

> 30 ~ 35 -80

> 35 ~ 40 -85

> 40 ~ 60 -90

41 27 -65

3.5Ni 345 440 ~ 690 21

<=25 -95

> 25 ~ 30 -100

> 30 ~ 35 -105

> 35 ~ 40 -110

> 40 ~ 60 -115

41 27 -90

5Ni 390 520 ~ 710 21

<=25 -110

> 25 ~ 30 -115

> 30 ~ 35 -120

> 35 ~ 40 -125

> 40 ~ 60 -130

41 27 -105

9Ni 490 640 ~ 830 19 <=60 -196 41 27 -165 a The horizontal value of shock absorption energy is applicable to steel plates, and the vertical value is applicable to profile steels.

6.4.2

Charpy (V-notch) shock absorption energy is calculated based on the arithmetic mean of 3 samples

The specified value in Table 4 is low, but it should not be lower than 70% of the specified value.

6.4.3

Thickness (Z-direction) performance The reduction in thickness in the thickness direction shall meet the requirements of GB/T 5313.

6.5 Surface quality

6.5.1

There should be no cracks, bubbles, scars, folds or pressing on the steel surface which are harmful to use. Steel should not be visual

Visible layers.

6.5.2

The surface of the steel is allowed to have a thin layer of iron oxide scale, rust that does not hinder the inspection of the surface defects, and the inferiority caused by the iron oxide scale falling off.

Significant surface roughness, indentation and other local defects, but its depth should not be greater than half of the thickness tolerance, and the minimum allowable steel should be guaranteed thickness.

6.5.3

When there are harmful defects on the steel surface, cleaning is allowed. The cleaning place should be smooth without edges and corners, and the minimum allowable thickness of the steel should be guaranteed.

6.5.4

The steel shall not be repaired.

6.6 Nondestructive testing

6.6.1

Thickness (Z direction) performance steel plates shall be subjected to ultrasonic testing one by one.The testing method shall be in accordance with NB/T 47013.3.

The supply and demand sides negotiate and determine. After the supply and demand parties negotiate and indicate in the contract, other testing methods and qualification levels can be determined.

6.6.2

According to the requirements of the purchaser, non-destructive testing of other steels can also be carried out after consultation between the supply and demand parties.

6.7 Special requirements

According to the requirements of the purchaser, the drop hammer test, the crack tip opening displacement (CTOD) test, and the residual magnetism test can be performed after consultation between the supply and demand sides.

7.1 Chemical composition

The chemical composition analysis of steel is usually carried out according to GB/T 4336, GB/T 20123, GB/T 20124 or other general methods.

Press GB/T 223.5, GB/T 223.9, GB/T 223.12, GB/T 223.14, GB/T 223.19, GB/T 223.23, GB/T 223.25,

GB/T 223.26, GB/T 223.37, GB/T 223.40, GB/T 223.62, GB/T 223.63, GB/T 223.67, GB/T 223.69 or

GB/T 20125.

7.2 Other inspection items

The test method for each batch of steel inspection items shall meet the requirements of Table 5.

Table 5 Inspection items, sampling quantity, sampling method and test method

Sampling method Sampling method Test method

1 chemical composition 1 per furnace GB/T 20066 see 7.1

7.3 Small size specimen impact test

The impact test specimens of steel plates shall be transverse specimens, and the impact test specimens of profile steels shall be longitudinal specimens. For steel plates with a thickness of less than 12mm,

Charpy (V-notch) impact test is performed with a small-sized sample.When the thickness of the steel plate is> 8mm ~ < 12mm, the sample size is 7.5mm ×

When the thickness is 10mm × 55mm and the steel plate thickness is 6mm ~ 8mm, the sample size is 5mm × 10mm × 55mm. Less than 6mm

The steel plate may not be subjected to an impact test. The conversion relationship between the impact absorption energy of the small sample and the standard sample is shown in Table 6.

Table 6 Conversion relationship between impact absorption energy of small-size samples and standard samples

Conversion factor of width of small sample/mm and impact absorption energy of standard sample

5 2/3

7.4 Dimension inspection

7.4.1

The size and shape of the steel shall be checked with suitable measuring tools.

7.4.2

The average thickness of the steel plate is measured as follows.

a) The average thickness of the steel plate can be measured by automatic or manual methods;

b) Measurement position of the side of the steel plate. When using the automatic method to measure, the distance from the side to the side is not less than 10mm and not more than 300mm.

Measurement within the area; when measuring by manual method, measure within a range of not less than 10mm and not more than 100mm from the side;

c) Refer to Figure 1 for the schematic diagram of the average thickness measurement of the steel plate. As shown in Figure 1, select at least two lines for measurement, and select at least three for each line.

Measurement points (when there are more than 3 measurement points, the measurement points of each line should be consistent), and the average thickness of the steel plate is calculated according to the average value.

Figure 1 Schematic diagram of average thickness measurement of steel plates

8.1

Inspection and acceptance of steel shall be carried out by the supplier's quality supervision and inspection department.

8.2

Steel plates shall be accepted in batches. Each batch of steel plates shall consist of steel plates of the same grade, same furnace number, same thickness, and the same rolling or heat treatment system.

Among them, steel sheets delivered in thermomechanical rolling (TMCP) and controlled rolling conditions should be sampled one by one, normalizing, normalizing and tempering, twice normalizing and tempering,

Quenching and tempering should be sampled by heat treatment.

8.3

Section steels shall be batches with the same furnace number, same specifications, the same rolling method and the same heat treatment system (maximum weight of each batch is 10t).

8.4

The batch of steel plates with performance requirements in the thickness direction shall meet the requirements of GB/T 5313.

8.5

The sampling quantity and sampling method of each batch of steel shall meet the requirements in Table 5.

8.6

The re-inspection and determination rules for the mechanical properties of steel plates shall meet the requirements of GB/T 17505.

8.7

The re-inspection and determination rules for the mechanical properties of section steel shall meet the requirements of GB/T 2101.

8.8

The re-inspection and judgment rules of the Z-direction steel thickness direction shall comply with the requirements of GB/T 5313.

8.9

The test results of mechanical properties and chemical composition are compared by the rounded value comparison method. The rounded rules shall meet the requirements of GB/T 8170.