CLASSIFICATION AND SPECIFICATIONS OF STEELS

Since there are literally thousands of different steels, it is difficult to classify them in a

simple straightforward manner. However, some guidelines can be used. For example, steels are generally classified as carbon steel or alloy steel. A classification system was developed by the SAE as early as 1911 to describe these carbon and alloy steels. The AISI collaborated with SAE to refine the compositional ranges of the classification that are used today. Recently, a Unified Numbering System (UNS) was established that incorporates the SAE/AISI number.

Many steel products are purchased by specifications describing specific compositional, dimensional, and property requirements. Specification organizations such as ASTM have developed numerous specifications for steel products and the testing of steel products. Some specific product user groups in the United States have developed their own specifications, e.g., the American Bureau of Ships (ABS) for ship plate and other marine products, Aerospace Materials Specifications (AMS) for aerospace applications, the American Railway Engineering and Maintenance of Way Association (AREMA) for rail and rail products, the SAE

for automotive applications, and the American Society of Mechanical Engineers (ASME) for steels produced to boiler code specifications. In Japan, there are standards developed by the Japanese Industrial Standards (JIS) Committee of the Ministry of International Trade and Industry. In the United Kingdom, there are the British Standards (BS) developed by the British Standards Institute. In Europe, Germany has the Deutsches Institut fu¨r Normung (DIN) standards, France the Association Francaise de Normalisation (AFNOR) standards, and Italy the Ente Nazionale Italiano di Unificazione (UNI) standards.

Specifications can be as simple as a hardness requirement, i.e., ASTM A1 for rail steel to elaborate compositional and property requirements as in ASTM A808, ‘‘High-strength low-alloy carbon–manganese–niobium–vanadium steel of structural quality with improved notch toughness.’’ Describing specific specifications is beyond the scope of this handbook, but many of the key sources can be found in the Bibliography at the end of this chapter.

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Bruce L. Bramfitt

International Steel Group, Inc.

Research Laboratories

Bethlehem, Pennsylvania

Reprinted from Handbook of Materials Selection, Wiley, New York, 2002, by permission of the publisher.

Mechanical Engineers’ Handbook: Materials and Mechanical Design, Volume 1, Third Edition.

Edited by Myer Kutz

Copyright  2006 by John Wiley & Sons, Inc.

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