1.3. Ordering Steel
1.3. Ordering Steel
The information required to be reported in an MTR is as given in ASTM A6/A6M-Section 14 for hot-rolled shapes and plates. This includes but is not limited to the steel grade and nominal sizes supplied and tension test results. This document may be in written form or, per ASTM A6/A6M-Section 14.8, transmitted electronically. ASTM A500/A500M Section 18 addresses this for HSS. ASTM A53/A53M Section 20 addresses this for steel pipe.
Two Modern Steel articles, “Made in America?” (02/09) and “The Buy American Act and the Structural Steel Industry” (10/11), discuss this issue in detail. (Both are available at (www. modernsteel.com)
ASTM A6/A6M covers the metric series of hot-rolled structural
shapes used in the United States. Because it is a soft metric
conversion, the metric series is physically identical to the U.S.
Customary-unit shape series. The dimensions are given in millimeters
(mm) with mass expressed in kilograms (kg); note that
the mass must be multiplied by the acceleration of gravity 9.81
m/s2 to obtain kiloNewtons (kN). The same is true for HSS
and steel pipe.
Note: A soft conversion is made by directly converting the
U.S. customary unit value to a metric equivalent—e.g., 1 in.
equals 25.4 mm. Conversely, a hard conversion is made by selecting
new values in round metric increments, such as replacing
1 in. with 25 mm.
ASTM A500 Grade C is most common when specifying square, rectangular and round HSS. These specifications cover cold-formed production of both welded and seamless HSS; ASTM A847 offers atmospheric corrosion resistance properties similar to that of ASTM A588 for W-shapes. Pipe-size rounds (P, PX and PXX) are also available in ASTM A53 Grade B material. See FAQs 1.4.6 through 1.4.8 for additional information on HSS and pipe section designations and material grades.
ASTM A1085 is a new specification for HSS. It offers improved material properties and design wall thickness equal to nominal wall thickness, among other desirable characteristics. For more information see www.aisc.org/a1085.
ASTM A992 (Fy = 50 ksi, Fu = 65 ksi) is the preferred material specification for wide-flange shapes. Material ductility is well defined for A992 since a maximum yield-to-tensile strength ratio of 0.85 is specified. Additionally, weldability is improved since a maximum carbon equivalent value of 0.45 (0.47 for shapes with flange thickness over 2 in.) is required. ASTM A992 is written to cover all hot-rolled shapes but it is predominantly used for W-shapes.
There are differences, although the two materials are similar. ASTM A992 should be specified for all W-shapes used today. It is like ASTM A572 Grade 50, but has better controls on chemistry and mechanical properties. It includes minimum values for yield and tensile strengths, a maximum ratio for yield strength to tensile strength and a maximum carbon equivalent value (also see FAQ 1.3.5)
There is overlap in the chemical, mechanical and other requirements in many ASTM specifications. For example, there is a range of chemistry, yield strength, tensile strength and other characteristics that is entirely within the requirements of ASTM A992, A572 Grade 50 and A36. Material with characteristics within this range of overlap is sometimes “multi-certified” by the producer—labeled with all ASTM material specifications it meets. Historically, this practice was most common for wide-flange material that was specified to ASTM A572 Grade 50. While the ASTM A572 specification was met, all of the requirements of the ASTM A36 specification were also met. The producers would then sell the material as either ASTM A36 or A572 Grade 50. With the shift to ASTM A992 as the base material for design and construction with wide-flange shapes, multi-certification is perhaps more of a historical note.
AISC has producer listings at www.aisc.org/steelavailability for hot-rolled shapes and HSS of various sizes and weights. Shapes producers have the ability to update these lists on a real-time basis. Contact information for many shapes producers is given on the website.