Реферат

This specification covers carbon and high-strength low alloy steel structural shapes, plates and bars, and quenched and tempered alloy steel for structural plates intended for use in bridges. Heat analysis shall be used to determine the percentage of carbon, manganese, phosphorus, sulfur, silicon, and copper for the required chemical composition. A tension test shall be used to determine the required tensile properties such as tensile strength, yield strength, and elongation. Materials shall undergo: (1) an impact test for non-fracture critical and fracture critical members; and (2) a Brinell hardness test for Grades 100 and 100W. Atmospheric corrosion resistance shall also be determined.

Область применения

1.1 This specification covers carbon and high-strength low-alloy steel structural shapes, plates, and bars and quenched and tempered alloy steel for structural plates intended for use in bridges. Seven grades are available in four yield strength levels as follows:

Grade U.S. [SI]

Yield Strength, ksi [MPa]

      36 [250]

 36 [250]    

      50 [345]

 50 [345]    

      50S [345S]

 50 [345]    

      50W [345W]

 50 [345]    

      HPS 50W [HPS 345W]

 50 [345]    

      HPS 70W [HPS 485W]

 70 [485]    

      HPS 100W [HPS 690W]

100 [690]    

1.1.1 Grades 36 [250], 50 [345], 50S [345S], and 50W [345W] are also included in Specifications A36/A36M, A572/A572M, A992/A992M, and A588/A588M, respectively. When the requirements of Table 8 or Table 9 or the supplementary requirements of this specification are specified, they exceed the requirements of Specifications A36/A36M, A572/A572M, A992/A992M, and A588/A588M.

1.1.2 Grades 50W [345W], HPS 50W [HPS 345W], HPS 70W [HPS 485W], and HPS 100W [HPS 690W] have enhanced atmospheric corrosion resistance (see 13.1.2). Product availability is shown in Table 1.

TABLE 1 Tensile and Hardness Requirements^A Note 1—Where “. . .” appears in this table, there is no requirement.

Grade

Plate Thickness,
in. [mm]

Structural Shape Flange
or Leg
Thickness, in. [mm]

Yield Point
or Yield
Strength,^B
ksi
[MPa]

Tensile
Strength,
ksi [MPa]

Minimum Elongation, %

Reduc-
tion of
Area^C,D
min, %

Plates and Bars^C,E

Shapes^E

8 in.
or 200
mm

2 in.
or 50
mm

8 in.
or 200
mm

2 in.
or 50
mm

36 [250]

to 4 [100], incl

to 3 in. [75 mm], incl

   36 [250] min

 58–80 [400–550]

 20

 23

 20

 21

 ...

 

over 3 in. [75 mm]

   36 [250] min

 58 [400] min

 ...

 ..

 20

 19

 ...

50 [345]

to 4 [100], incl

all

   50 [345] min

 65 [450] min

 18

 21

 18

 21^F

 ...

50S [345S]

^G

all

 50–65
[345–450]^HI

 65 [450]^H min

 ...

...

 18

 21

 ...

50W [345W] and
 HPS 50W
 [HPS 345W]

to 4 [100], incl

all

   50 [345] min

 70 [485] min

 18

 21

 18

 21^J

 ...

HPS 70W
 [HPS 485 W]

to 4 [100], incl

^G

    70 [485] min^B

 85–110 [585–760]

 ...

 19^K

 ...

 ...

 ...

HPS 100W
 [HPS 690W]

to 2¹/₂ [65], incl

^G

 100 [690] min^B

 110–130 [760–895]

 ...

 18^K

 ...

 ...

 ^L

 

over 2¹/₂ to 4
[65 to 100], incl^M

^G

 90 [620] min^B

 100–130 [690–895]

 ...

 16^K

 ...

 ...

 ^L

^A See specimen orientation and preparation subsection in the Tension Tests section of Specification A6/A6M. ^B Measured at 0.2 % offset or 0.5 % extension under load as described in Section 13 of Test Methods A370. ^C Elongation and reduction of area not required to be determined for floor plates. ^D For plates wider than 24 in. [600 mm], the reduction of area requirement, where applicable, is reduced by five percentage points. ^E  For plates wider than 24 in. [600 mm], the elongation requirement is reduced by two percentage points. See elongation requirement adjustments in the Tension Tests section of Specification A6/A6M. ^F Elongation in 2 in. or 50 mm: 19 % for shapes with flange thickness over 3 in. [75 mm].^G Not applicable. ^H The yield to tensile ratio shall be 0.87 or less for shapes that are tested from the web location; for all other shapes, the requirement is 0.85.^I A maximum yield strength of 70 ksi [480 MPa] is permitted for structural shapes that are required to be tested from the web location.^J For wide flange shapes with flange thickness over 3 in. [75 mm], elongation in 2 in. or 50 mm of 18 % minimum applies. ^K If measured on the Fig. 3 (Test Methods A370) 1¹/₂-in. [40–mm] wide specimen, the elongation is determined in a 2-in. or 50-mm gage length that includes the fracture and shows the greatest elongation. ^L 40 % minimum applies if measured on the Fig 3 (Test Methods A370) 1¹/₂-in. [40-mm] wide specimen; 50 % minimum applies if measured on the Fig. 4 (Test Methods A370) ¹/₂-in. [12.5-mm] round specimen.^M Not applicable to Fracture Critical Tension Components (see Table 9).TABLE 2 Grade 36 [250] Chemical Requirements (Heat Analysis) Note 1—Where “. . .” appears in this table there is no requirement. The heat analysis for manganese shall be determined and reported as described in the Heat Analysis section of Specification A6/A6M.

Product
Thickness,
in. (mm)

Shapes^A
All

Plates^B

Bars^B

To ³/₄ 
[20], incl

Over ³/₄ 
to 1¹/₂ [20 to 40], incl

Over 1¹/₂ to
2¹/₂ [40 to 65], incl

Over 2¹/₂ to 4
[65 to 100],
incl

To ³/₄ 
[20],
incl

Over ³/₄ to
1¹/₂ [20 to
40], incl

Over 1¹/₂ to
4 [100], incl

 

Carbon, max, %

0.26

0.25

0.25

0.26

0.27

0.26

0.27

0.28

Manganese, %

...

...

0.80–1.20

0.80–1.20

0.85–1.20

...

0.60–0.90

0.60–0.90

Phosphorus, max, %

0.04

0.04

0.04

0.04

0.04

0.04

0.04

0.04

Sulfur, max, %

0.05

0.05

0.05

0.05

0.05

0.05

0.05

0.05

Silicon, %

0.40 max

0.40 max

0.40 max

0.15–0.40

0.15–0.40

0.40 max

0.40 max

0.40 max

Copper, min, % when  copper steel is specified

0.20

0.20

0.20

0.20

0.20

0.20

0.20

0.20

^A Manganese content of 0.85 to 1.35 % and silicon content of 0.15 to 0.40 % is required for shapes with flange thickness over 3 in. [75 mm]. ^B For each reduction of 0.01 % below the specified carbon maximum, an increase of 0.06 % manganese above the specified maximum will be permitted up to a maximum of 1.35 %. TABLE 3 Grade 50 [345] Chemical Requirements^A (Heat Analysis)

 

 

 

 

 

Silicon^C

Columbium,
Vanadium
and Nitrogen

Maximum Diameter,
Thickness, or
Distance Between
Parallel Faces, in. [mm]

Carbon,
max, %

Manganese,^B
max, %

Phosphorus,
max, %

Sulfur,
max, %

Plates to
1¹/₂-in. [40-mm] Thick,
Shapes with flange
or leg
thickness
to 3 in. [75 mm]
inclusive, Sheet Piling, Bars, Zees, and Rolled
Tees,
max, %^D

Plates Over
1¹/₂-in. [40-mm]
Thick and Shapes
with flange thickness
over 3 in. [75 mm], %

 

4 [100]

0.23

1.35

0.04

0.05

0.40

0.15–0.40

^E

   ^A Copper when specified shall have a minimum content of 0.20 % by heat analysis (0.18 % by product analysis).

   ^B Manganese, minimum by heat analysis of 0.80 % (0.75 % by product analysis) shall be required for all plates over ³/₈ in. [10 mm] in thickness; a minimum of 0.50 % (0.45 % by product analysis) shall be required for plates ³/₈ in. [10 mm] and less in thickness, and for all other products. The manganese to carbon ratio shall not be less than 2 to 1. For each reduction of 0.01 percentage point below the specified carbon maximum, an increase of 0.06 percentage point manganese above the specified maximum is permitted, up to a maximum of 1.60 %.

   ^C Silicon content in excess of 0.40 % by heat analysis must be negotiated.

   ^D Bars over 1¹/₂ in. [40 mm] in diameter, thickness, or distance between parallel faces, shall be made by a killed steel practice.

   ^E Alloy content shall be in accordance with Type 1, 2, 3, or 5 and the contents of the applicable elements shall be reported on the test report.

Type

Elements

Heat Analysis, %

1

Columbium^A

0.005–0.05^B

2

Vanadium

0.01–0.15

3

Columbium^A
Vanadium
Columbium plus vanadium

0.005–0.05^B
0.01–0.15
0.02–0.15^C

5

Titanium
Nitrogen
Vanadium

0.006–0.04
0.003–0.015
0.06 max

^A Columbium shall be restricted to Grade 50 [345] plate, bar, zee, and rolled tee thickness of ³/₄ in. [20 mm] max, and to shapes with flange or leg thickness to 1¹/₂ in. [40 mm] inclusive unless killed steel is furnished. Killed steel shall be confirmed by a statement of killed steel on the test report, or by a report of the presence of a sufficient quantity of a strong deoxidizing element, such as silicon at 0.10 % or higher, or aluminum at 0.015 % or higher.^B Product analysis limits = 0.004 to 0.06 %.^C Product analysis limits = 0.01 to 0.16 %.TABLE 4 Grade 50W [345 W] Chemical Requirements (Heat Analysis) Note 1—Types A and B are equivalent to Specification A588/A588M, Grades A and B, respectively.

Element
  

Composition, %^A

Type A

Type B

 

Carbon^B

0.19 max

0.20 max

Manganese^B

0.80–1.25

0.75–1.35

Phosphorus

0.04 max

0.04 max

Sulfur

0.05 max

0.05 max

Silicon

0.30–0.65

0.15–0.50

Nickel

0.40 max

0.50 max

Chromium

0.40–0.65

0.40–0.70

Copper

0.25–0.40

0.20–0.40

Vanadium

0.02–0.10

0.01–0.10

^A Weldability data for these types have been qualified by FHWA for use in bridge construction.^B For each reduction of 0.01 percentage point below the specified maximum for carbon, an increase of 0.06 percentage point above the specified maximum for manganese is permitted, up to a maximum of 1.50 %.TABLE 5 Grades HPS 50W [HPS 345W] and HPS 70W [HPS 485 W], and HPS 100W [HPS 690W] Chemical Requirements (Heat Analysis) Note 1—Where “. . .” appears in this table, there is no requirement.

Element

Composition, %

Grades
HPS 50W [HPS 345W],
HPS 70W [HPS 485W]

Grade
HPS 100W [HPS 690W]

Carbon

0.11 max

0.08 max

Manganese

 

 

   2.5 in. [65 mm] and under

1.10–1.35

0.95–1.50

   Over 2.5 in. [65 mm]

1.10–1.50

0.95–1.50

Phosphorus

0.020 max

0.015 max

Sulfur^A

0.006 max

0.006 max

Silicon

0.30–0.50

0.15–0.35

Copper

0.25–0.40

0.90–1.20

Nickel

0.25–0.40

0.65–0.90

Chromium

0.45–0.70

0.40–0.65

Molybdenum

0.02–0.08

0.40–0.65

Vanadium

0.04–0.08

0.04–0.08

Columbium (Niobium)

. . .

0.01–0.03

Aluminum

0.010–0.040

0.020–0.050

Nitrogen

0.015 max

0.015 max

^A The steel shall be calcium treated for sulfide shape control.TABLE 6 Grade 50S [345S] Chemical Requirements (Heat Analysis)

Element   

Composition,  %

 

 

Carbon, max

 0.23

 

Manganese

 0.50 to 1.60^A

 

Silicon, max

 0.40

 

Vanadium, max

 0.15^B

 

Columbium, max

 0.05^B

 

Phosphorus, max

 0.035

 

Sulfur, max

 0.045

 

Copper, max

 0.60

 

Nickel, max

 0.45

 

Chromium, max

 0.35

 

Molybdenum, max

 0.15

^A Provided that the ratio of manganese to sulfur is not less than 20 to 1, the minimum limit for manganese for shapes with flange or leg thickness not exceeding 1 in. [25 mm] shall be 0.30 %.^B The sum of columbium and vanadium shall not exceed 0.15 %.TABLE 7 Relationship Between Impact Testing Temperature Zones and Minimum Service Temperature

Zone

Minimum Service Temperature, °F [°C]

 

1

0

 [−18]

2

below 0 to −30

 [−18 to −34]

3

below −30 to −60

 [−34 to −51]

1.2 Grade HPS 70W [HPS 485W] or HPS 100W [HPS 690W] shall not be substituted for Grades 36 [250], 50 [345], 50S [345S], 50W [345W], or HPS 50W [HPS 345W]. Grade 50W [345W], or HPS 50W [HPS 345W] shall not be substituted for Grades 36 [250], 50 [345] or 50S [345S] without agreement between the purchaser and the supplier.

1.3 When the steel is to be welded, it is presupposed that a welding procedure suitable for the grade of steel and intended use or service will be utilized. See Appendix X3 of Specification A6/A6M for information on weldability.

1.4 For structural products to be used as tension components requiring notch toughness testing, standardized requirements are provided in this standard, and they are based upon American Association of State Highway and Transportation Officials (AASHTO) requirements for both fracture critical and non-fracture critical members.

1.5 Supplementary requirements are available but shall apply only if specified in the purchase order.

1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.7 For structural products produced from coil and furnished without heat treatment or with stress relieving only, the additional requirements, including additional testing requirements and the reporting of additional test results, of Specification A6/A6M apply.