ASTM A709/A709M : 16a

Standard Specification for Structural Steel for Bridges

Standard Details

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 9 or Table 10 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.

(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.

(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 10).

(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 %.

(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) A maximum phosphorus content of 0.04 % and a maximum sulfur content of 0.05 % are permitted for the following materials:

· Structural shapes

· Bars

· Plates with widths up to and including 15 in. [380 mm]

(D) Silicon content in excess of 0.40 % by heat analysis must be negotiated.

(A) 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.

(B) Product analysis limits = 0.004 to 0.06 %.

(D) Product analysis limits = 0.01 to 0.16 %.

(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 %.

(C) A maximum phosphorus content of 0.04 % and a maximum sulfur content of 0.05 % are permitted for the following materials:

· Structural shapes

· Bars

· Plates with widths up to and including 15 in. [380 mm]

(A) The steel shall be calcium treated for sulfide shape control.

(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 %.

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.