Astm A992 Grade 50 Properties

[Aureo Harvey]

Althoughthe A913 specification has been around for over 20 years, there has been a renewed interest in QST high-strength structural steel (65, 70, 80 ksi) like Aeos in recent years due to the significant benefits compared to traditional ASTM A992 steel.

The QST thermo-mechanical treatment process is the interrupted quench of large steel wide flange sections followed by a self-tempering process. The interrupted quench is accomplished with water spray modules located after the last stand in the structural mill where the steel is rapidly cooled but has enough retained thermal energy to temper the steel as well. This process produces a steel wide flange section with higher yield and tensile strength properties combined with excellent ductility.

Aeos ASTM A913 also offers metallurgical benefits compared to A992 including enhanced brittle fracture resistance, increased ductility, improved weldability and a carbon maximum about half of A992. When comparing Carbon Equivalent (C.E.) maximums, Aeos has a comparable C.E. level to A992 but with higher tensile properties. Comparable C.E. levels can lead to welding efficiencies when using Aeos.

The steel you use matters and not all steel is produced the same way. Extractive or integrated steelmaking involves mining raw materials and using blast furnace and basic oxygen furnace (BF/BOF), a carbon-intensive steelmaking technology. Alternately, Nucor utilizes a sustainable, circular steelmaking process using electric arc furnace (EAF) technology to create steel with less than half the carbon emissions compared to steel created using the integrated steelmaking process. Learn more about the two ways to make steel.

Aeos is the lowest-embodied-carbon steel of its kind, made with more than 95% recycled content using our circular steelmaking process. Nucor is the only domestic producer of Aeos ASTM A913 which can simplify your supply chain by eliminating challenges with overseas imports while reducing additional international shipping carbon emissions and fees.

In addition to the material strength and sustainability benefits, Aeos can also lead to fabrication efficiencies. Since less material is needed to support the same loads compared to A992, Aeos weighs less and is easier and safer to move around the shop and/or jobsite.

This weldability data consists of a complete joint penetration groove weld according to AWS D1.1 and an oblique Y groove test, according to AWS B4.0. This is done primarily to verify the preheat temperature requirements of the WPS and to give the fabricator/customer guidance on the development of their own WPS. As detailed throughout the AWS guidelines, preheat conditions for welding Aeos can be greatly reduced or eliminated if completed in accordance with AWS D1.1 guidance. This can result in significant time, labor and material savings, both in the fabrication shop and on the jobsite. Additionally, energy consumption is reduced, further enhancing the environmental benefits of using Aeos. Multiple projects have utilized Aeos Grade 50 material in lieu of A992 Grade 50 simply due to the welding preheat benefits that are inherent to the material.

For building structures, the most significant advantage of this specification (A913) is for column and truss sections where the designer can realize a 10 to 20 percents by using the higher strength available in Aeos Grade 65 as compared to the standard 50 ksi yield strength of A992. This increased strength has allowed steel structure design to compete successfully against other materials (Vernon, Shane, P.E. Structure Magazine, August 2020).

Buchanan County in Iowa has completed a single span bridge made with wide flange sections produced to Aeos Grade 65/A709 QST 65 specification. Preliminary fatigue tests comparing A913 to A992 were performed at Edison Welding Institute in Columbus, Ohio indicated a higher endurance stress when utilizing Aeos. More fatigue property research needs to be completed to make this finding conclusive; however, the initial data is promising.

Aeos is available in several W-sections. Lighter weights are not available in A913 due to the thermal energy requirement of the process as the wide flange section has to have enough thermal mass to temper the section after quenching. Designers are encouraged to contact Nucor to determine section availability in A913 and rolling schedule/delivery time frames or to learn more about Aeos specifications, construction advantages, welding benefits and availability.

The potential of higher strengths of A913 is continually being researched. We started with Aeos Grade 65 but have continuously developed higher grades including Grade 80. The use of higher strength structural steel that is produced in the as-rolled condition, versus built-up sections, would allow design engineers to take advantage of the increased benefits of steel structures on projects.

Are you interested in receiving AIA or NCSEA credit plus a Certificate of Completion about this topic? Our next accredited webinar, AEOS: A913 HIGH-STRENGTH STEEL, will be on August 28, 2024 at 2:00 PM ET.

In Europe, structural steel must comply with the European Standard EN 10025, which is governed by the European Committee for Iron and Steel Standardization (ECISS), a subset of the European Committee for Standardization (CEN).

Depending on the manufacturing process, chemical composition and relevant application, further letters and classifications might be used to reference particular grades or products of structural steel.

The chemical composition of structural steel is extremely important and highly regulated. It is a fundamental factor which defines the mechanical properties of the steel. In the following table, you can see the maximum percentage levels of certain regulated elements present in European structural steel grades S235, S275, and S355.

The Chemical composition of Structural Steel is extremely important and highly regulated. It is a fundamental factor which defines the Mechanical properties of the steel material. In the following table you can see the Max % levels of certain regulated elements present in European Structural steel grades S235, S275 and S355.

The chemical composition of structural steel is incredibly important to the engineer and will change with specific grades depending on their intended use. For example, S355K2W is a structural steel that has been hardened, denoted by K2, and has been designed with a chemical composition to withstand increased weathering - W. Therefore, this grade of structural steel will have a slightly different chemical composition to the standard S355 grade.

The mechanical properties of structural steel are fundamental to its classification and application. Even though chemical composition is a dominant factor in determining the mechanical properties of steel, it is also very important to understand the minimum standards for the mechanical properties or performance characteristics, such as yield strength and tensile strength, which are described in more detail below.

The yield strength of structural steel measures the minimum force required to create a permanent deformation in the steel. The naming convention used in European Standard EN10025 refers to the minimum yield strength of the steel grade tested at 16mm thick.

Structural steel comes in many grades but is normally sold pre-formed with a defined cross-sectional shape, designed for specific applications. For example, it is common to find structural steel sold in I-beams, Z-beams, box lintels, hollow structural section (HSS), L-shaped and steel plate.

Depending on the desired application, an engineer will specify a grade of steel -usually to meet minimum strength, maximum weight and possibly weathering requirements, as well as the sectional shape - relative to the desired location and expected load to be carried or job to be performed.

It will come as no surprise that the construction industry is the biggest consumer of structural steel, where it is used for a number of purposes. Whether a small box lintel is used to carry the load of a structural wall in a residential property or a vast I-beam is bolted in place to hold the road surface on a bridge, structural steel can be specified, designed and fabricated for any type of job.

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Recently in the United States, there has been increasing interest in developing engineered approaches to structural fire safety of buildings as an alternative to conventional code-based prescriptive approaches. With an engineered approach, the response of a structure to fire is computed and appropriate design measures are taken to assure acceptable response. In the case of steel buildings, one of the key elements of this engineered approach is the ability to predict the elevated-temperature properties of structural steel. Although several past research studies have examined elevated-temperature properties of structural steel, there are still major gaps in the experimental database and in the available constitutive models, particularly for ASTM A992 structural steel, a commonly used grade. Accordingly, the overall objective of this dissertation is to significantly enlarge the experimental database of the elevated-temperature properties for ASTM A992 structural steel and developing improved constitutive models for application in structural-fire engineering analysis.

Specific issues examined in this dissertation include the following: tensile properties at elevated temperatures; room-temperature mechanical properties after heating and cooling; and creep and relaxation properties at elevated temperatures. For the elevated-temperature studies of tension, creep and relaxation, constitutive models were developed to describe the measured experimental data. These models were compared to existing theoretical and empirical models from the literature.

3a8082e126