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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 heat number, steel grade, and nominal sizes supplied and tension test and chemical composition test results. This document may be in written form or, per ASTM A6/A6M-Section 14.8, transmitted electronically. ASTM A500/A500M requires a certificate of conformance and the chemical composition of selected elements. ASTM A53/A53M requires a certificate of compliance on request. ASTM A1085/A1085M requires that the producer provide a certificate of compliance if requested in the purchase order. Similarly, the producer will provide a test report if required in the purchase order.
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)
Europe, UK and Asia use different shapes defined in their own standards. ASTM A6/A6M provides SI dimensions for 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/A500M 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/A847M offers atmospheric corrosion resistance properties similar to that of ASTM A588/588M for W-shapes. Pipe-size rounds (P, PX and PXX) are also available in ASTM A53/A53M Grade B material. See FAQs 1.4.6 and 1.4.7 for additional information on HSS and pipe section designations and material grades.
ASTM A1085/A1085M 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/A992M (Fy = 50 ksi, Fu = 65 ksi) is the preferred material specification for wide-flange shapes. Material ductility is well defined for ASTM A992/A992M 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/A992M 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/A992M should be specified for all W-shapes used today. It is like ASTM A572/A572M Grade 50, but has better controls on chemistry and mechanical properties. It includes minimum values for yield and tensile strengths, a maximum yield strength, a maximum ratio for yield strength to tensile strength, and a maximum carbon equivalent value (also see FAQ 1.3.5)
There are many standard specifications for steel products. Standards are developed to suit the needs of a market. Many standards have overlapping requirements, Certificates of conformance and material test reports for materials that comply completely with more than one standard will indicate those standards. These materials are considered ‘multi-certified.’ The practice is common and an indication of well-controlled processes.
AISC has producer listings at 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. Producers publish rolling schedules. Those schedules indicate which shapes are rolled on a periodic basis and those that are subject to accumulation of orders. Shapes that are rolled on a periodic basis are more readily available than those that are subject to accumulation of orders.