Introduction to the ASTM Designation System

Abstract: ASTM specifications represent a consensus among producers, specifiers, fabricators, and users of steel mill products. ASTM’s designation system for metals consists of a letter (A for ferrous materials) followed by an arbitrary sequentially assigned number. These designations often apply to specific products, for example A548 is applicable to cold-heading quality carbon steel wire for tapping or sheet metal screws.

Steel standards are instrumental in classifying, evaluating, and specifying the material, chemical, mechanical, and metallurgical properties of the different types of steels, which are primarily used in the production of mechanical components, industrial parts, and construction elements. The most widely used standard specifications for steel products in the United States are those published by ASTM (American Society for Testing and Materials).

ASTM specifications represent a consensus among producers, specifiers, fabricators, and users of steel mill products. In many cases, the dimensions, tolerances, limits, and restrictions in the ASTM specifications are similar to or the same as the corresponding items in the standard practices contained in the AISI Steel Products Manuals.

Many of the ASTM specifications have been adopted by the American Society of Mechanical Engineers (ASME) with little or no modification; ASME uses the prefix S and the ASTM designation for these specifications. For example, ASME-SA213 and ASTM A 213 are identical.

ASTM’s designation system for metals consists of a letter (A for ferrous materials) followed by an arbitrary sequentially assigned number. These designations often apply to specific products, for example A548 is applicable to cold-heading quality carbon steel wire for tapping or sheet metal screws. Metric ASTM standards have a suffix letter M.

Examples of the ASTM ferrous metal designation system, describing its use of specification numbers and letters, are shown below:

Example - ASTM A 582/A 582M-95b (2000), Grade 303Se-Free-Machining Stainless Steel Bars:

‘A’ describes a ferrous metal, but does not sub classify it as cast iron, carbon steel, alloy steel, tool steel, or stainless steel;

582 is a sequential number without any relationship to the metal’s properties;

M indicates that the standard A582M is written in rationalized SI units (the M comes from the word Metric), hence together 582/A582M includes both inch-pound and SI units;

95 indicates the year of adoption or last revision and a letter b following the year indicates the third revision of the standard in1995;

(2000), a number in parentheses, indicates the year of last re-approval;

Grade 300Se indicates the grade of the steel, and in this case, it has a Se (selenium) addition.

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Types 304, 316, 410 and others are based on the SAE designation system for stainless steels (see SAE and former AISI description that follows).

Another use of ASTM grade designators is found in pipe, tube, and forging products, where the first letter P refers to pipe, T refers to tube, TP may refer to tube or pipe, and F refers to forging.

Examples are found in the following ASTM specifications:

ASTM A 335/A335-03, Grade P22; Seamless Ferritic Alloy-Steel Pipe for High Temperature Service;

ASTM A 213/A213M-03a, Grade T22; Seamless Ferritic and Austenitic Alloy Steel Boiler, Superheater and Heat-Exchanger Tubes;

ASTM A 312/A312M-03, Grade TP304; Seamless and Welded Austenitic Stainless Steel Pipe;

ASTM A 336/A336M-03a, Class F22-Steel Forgings, Alloy, for Pressure and High-Temperature Parts.

Within the steel industry, the terms Grade, Type, and Class are generally defined as follows: Grade is used to describe chemical composition; Type is used to define the deoxidation practice; and Class is used to indicate other characteristics such as strength level or surface finish. However, within the ASTM standards, these terms were adopted and used to identify a particular metal within a metal standard and used without any strict definition. Although there are differences between the ASTM and traditional definitions of these terms ASTM have applied some loose rules to the use of this terminology in their designation system :

Example 1 - ASTM A 106-02a Grade A, Grade B, Grade C - Seamless Carbon Steel Pipe for High-Temperature Service: Typically an increase in alphabet (such as letters A, B, C) results in higher tensile or yield strength steels, and if it’s an unalloyed carbon steel, an increase in carbon content;

In this case: Grade A:0.25%C (max), 48 ksi tensile strength (min); Grade B: 0.30%C (max),

60 ksi tensile strength (min); Grade C 0.35%C (max), 70 ksi tensile strength (min).

Example 2 - ASTM A 276-03, Type 304, 316, 410 – Stainless and Heat Resisting Steel Bars and Shapes:

Introduction to the SAE-AISI Designation System

Abstract: The SAE system uses a basic four-digit system to designate the chemical composition of carbon and alloy steels. The first digit (1), of this designation indicates a carbon steel; i.e., carbon steels comprise 1xxx groups in the SAE-AISI system and are subdivided into four categories due to the variance in certain fundamental properties among them.

For many years, certain grades of carbon and alloy steels have been designated by a four-digit AISE/SAE numerical index system that identified the grades according to standard chemical compositions. Since the American Iron and Steel Institute (AISI) ceased writing material specifications, the relationship between AISI and grade designations has been discontinued. From point of edition of the 1995 Iron and Steel Society (ISS) Strip Steel Manual, the four-digit designations are referred to solely as SAE Designations.

The SAE system uses a basic four-digit system to designate the chemical composition of carbon and alloy steels. The simplest system for designation of steel is schematically shown in Figure 1.

Figure 1: Schematic Representation of AISI/SAE Steel Designation System

Figure 1 demonstrates that the SAE-AISI system uses a four-digit number to designate a carbon and alloy steel and refers to its specific chemical composition. It is worth noting however, that there are also certain types of alloy steels that are designated by five digits (51XXX; 52XXX).

The first digit (1), of this designation indicates a carbon steel; i.e., carbon steels comprise 1xxx groups in the SAE-AISI system and are subdivided into four categories due to the variance in certain fundamental properties among them. Thus the plain carbon steels are comprised within the 10xx series (containing 1.00% Mn maximum); resulfurized carbon steels within the 11xx series; resulfurized and rephosphorized carbon steels within the 12xx series; and non-resulfurized high-manganeze (up-to 1.65%) carbon steels which are produced for applications requiring good machinability are comprised within the 15xx series.

The SAE-AISI system then classifies all other alloy steels using the same four digit index as follows: 2 - Nickel steels; 3 - Nickel-chromium steels; 4 - Molybdenum steels; 5 - Chromium steels; 6 - Chromium-vanadium steels; 7 - Tungsten-chromium steels; 9 - Silicon-manganese steels.

Table 1: The SAE/AISI steel numbering designation system

Click on the link to see a list of AISI-SAE standards covering the following material categories:

Group of standards for structural and constructional steels

Group of standards for stainless and heat resisting steels

Group of standards for steel castings

Carbon steels

10XX Plain carbon, Mn 1.00% max11XX Resulfurized free machining12XX Resulfurized/rephosphorized free machining15XX Plain carbon, Mn 1.00-1.65%

Manganese steels 13XX Mn 1.75%

Nickel steels23XX Ni 3.50%25XX Ni 5.00%

Nickel-chromium steels

31XX Ni 1.25%, Cr 0.65-0.80%32XX Ni 1.75%, Cr 1.07%33XX Ni 3.50%, Cr 1.50-1.57%34XX Ni 3.00%, Cr 0.77%

Molybdenum steels40XX Mo 0.20-0.25%44XX Mo 0.40-0.52%

Chromium-molybdenum steels 41XX Cr 0.50-0.95%, Mo 0.12-0.30%

Nickel-chromium-molybdenum steels43XX Ni 1.82%, Cr 0.50-0.80%, Mo 0.25%47XX Ni 1.05%, Cr 0.45%, Mo 0.20-0.35%

Nickel-molybdenum steels46XX Ni 0.85-1.82%, Mo 0.20-0.25%48XX Ni 3.50%, Mo 0.25%

Chromium steels

50XX Cr 0.27-0.65%51XX Cr 0.80-1.05%

50XXX Cr 0.50%, C 1.00% min51XXX Cr 1.02%, C 1.00% min52XXX Cr 1.45%, C 1.00% min

Chromium-vanadium steels 61XX Cr 0.60-0.95%, V 0.10-0.015%Tungsten-chromium steels 72XX W 1.75%, Cr 0.75%

Nickel-chromium-molybdenum steels

81XX Ni 0.30%, Cr 0.40%, Mo 0.12%86XX Ni 0.55%, Cr 0.50%, Mo 0.20%87XX Ni 0.55%, Cr 0.50%, Mo 0.25%88XX Ni 0.55%, Cr 0.50%, Mo 0.35%

Silicon-manganese steels 92XX Si 1.40-2.00%, Mn 0.65-0.85%, Cr 0-0.65%

Nickel-chromium-molybdenum steels

93XX Ni 3.25%, Cr 1.20%, Mo 0.12%94XX Ni 0.45%, Cr 0.40%, Mo 0.12%97XX Ni 0.55%, Cr 0.20%, Mo 0.20%98XX Ni 1.00%, Cr 0.80%, Mo 0.25%

The second digit of the series indicates the concentration of the major element in percentiles (1 equals 1%). The last two digits of the series indicate the carbon concentration to 0.01%.

Example: SAE 5130 indicates a chromium steel alloy, containing 1% of chromium and 0.30% of carbon.

Table 1 shows the SAE/AISI steel Numbering designation system

Additional letters added between the second and third digits include B when boron is added (between 0.0005 and 0.003%) for enhanced hardenability, and L when lead is added (between 0.15 and 0.35%) for enhanced machinability. The prefix M is used to designate merchant quality steel (the least restrictive quality descriptor for hot-rolled steel bars used in noncritical parts of structures and machinery). The prefix E (electric-furnace steel) and the suffix H (hardenability requirements) are mainly applicable to alloy steels. The full series of classification groups is shown in Table 2-4.

Metal Composition

Generally, all metals can be classified such as ferrous, non-ferrous and alloys. Ferrous group of metals is composed mainly of iron. They may have small amounts of other metals or other elements added such as carbon, manganese, nickel, chromium, silicon, titanium, tungsten etc., to give the required properties. Non-Ferrous are metals which do not contain any iron as a component. The common pure metals are: aluminum, copper, lead, zinc, tin, silver and gold. Alloys: An alloy is a new metal which is formed by mixing two or more metals and sometimes other elements together. The most used metals are: Iron, Aluminum, Copper, Titanium, Zinc, Magnesium etc. Iron is the basic component of steel. When carbon, a nonmetal is added to iron in amounts to 2.1 %, the result is an alloy known as steel. In connection with mentioned above steel is an alloy composed by iron and other elements such as carbon, manganese, phosphorus, sulfur, nickel, chromium, tungsten, niobium (columbium), titanium etc. Each element that is added to the basic constituent of iron has some effect on the properties of the steels. The alloying additions are responsible for many differences between the various types or grades of steels. Based on carbon content, the steels are divided into three main groups: low carbon steels /AISI1005 to AISI 1026, IF, HSLA, TRIP, TWIP steels etc/, middle carbon steels /AISI 1029 to AISI 1053/, and high carbon steels /AISI1055 to AISI1095/. On the other hand, according to EN standard, the steel grades are divided into following steel groups: non alloy steels /EN DC01-DC06; S235; S275, etc./, alloy steels /2CrMo4; 25CrMo4 etc./, stainless steels, tool steels /DIN-EN 1.1545; AISI/SAE W110; DIN/EN 1.2436 AISI/SAE D6/, steels for sheet and strip, and steels for electrical sheet and strip /EN 1.0890; EN 1.0803 etc./. On the other hand, the most widely used non-ferrous metals are aluminum, copper, titanium, gold etc. The aluminum industry uses aluminum as cast and wrought aluminum alloys. These two classes can be further subdivided into families of alloys based on chemical composition and on temper designation. According to common accepted CEN standard designation systems, the most common aluminum grades are:

Corrosion resistant alloys, such as Commercially Pure grades 1,2,3,4, Ti-Pd (grade 7 and 16), Ti-3Al-2.5V (grade 9 and18), Ti-Pd (grade 11 and 17), Ti-0.3Mo-0.8Ni (grade 12), BETAC (grade 19 and 20)

High strength alloys are Ti-6Al-4V (grade 5), Ti-5Al-2.5Sn (grade 6), Ti-6Al-6V-2Sn, Ti-10V-2Fe-3Al, Ti-15V-3Cr-3Sn-3Al, Ti-5Al-2Sn-4Mo-2Zr-4Cr, Ti-4Al-4Mo-2Sn (Ti550), Ti-

8Al-1Mo-1V.

High temperature alloys like Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-4Zr-6Mo, Ti-11Sn-5Zr-2.5Al-1Mo-0.2Si (IMI679), Ti-6Al-5Zr-0.5Mo-Si (IMI685), Ti-5.5Al-3.5Sn-Zr-1Nb (IMI829), Ti-5.8Al-4Sn-3.5Zr-0.7Nb (IMI 834), TIMETAL 1100 etc.

The purity or fineness of gold in the jewelry is indicated by its karat number. 24 karat (24K or 24 K) gold is as pure as gold for jewelry gets. 24K gold is also called fine gold and it is greater than 99.7% pure gold. Proof gold is even finer, with over 99.95% purity, but it is only used for standardization purposes and is not available for jewelry. The most widely used Copper and its alloys are in forms of brasses and bronzes. A Brass is a copper-zinc alloy with 5 - 42 % zinc (CuZn28, CuZn37, CuZn42 etc.). The German name is Messing (Ms58 = CuZn42). Brasses are usually yellow in color. A bronze is an alloy of copper and other metals, most often tin (CuSn6, CuSn10, CuSn14 etc.), phosphorus (PB1C, PB4C, PB3, LPB1C etc.), Manganese(HTB1, HTB2, HTB3 ), but also aluminum (AB1C, AB2C) and leaded (LG1C, LG2C,LG3C, etc.).

1xxx Series: / 1050, 1060, 1100, 1145, 1200, 1230, 1350 etc./ 2xxx Series: /2011, 2014, 2017, 2018, 2124, 2219, 2319, 201.0; 203.0; 206.0; 224.0; 242.0 etc./ 3xxx Series: /3003, 3004, 3105, 383.0; 385.0; A360; 390.0/ 4xxx Series: /4032, 4043, 4145, 4643 etc./ 5xxx Series: /5005, 5052, 5083, 5086 / 6xxx Series: /6061, 6063/ 7xxx Series: /7075, 7050, 7049, 710.0; 711.0 etc/ 8xxx Series: /8006; 8111; 8079; 850.0; 851.0; 852.0/

Regarding to the properties, titanium and titanium alloys can be divided into three main groups: