Alloy Structural Steel Grade Designation Method
Alloy structural steel is a type of special steel used in the construction of buildings, machines and tools. It is made of a variety of elements added in certain proportions. The different elements lead to different mechanical properties, and in certain occasions the overall mechanical performance. In order to clearly and easily classify the different grades of alloy structural steel, a grade designation method is adopted.
The grade designation of alloy structural steels according to the Structural Steel Standard of the American Iron and Steel Institute (AISI) consists of a letter and a number. The letter indicates the type of alloying agent and the number is the average carbon content expressed as a percentage. For example, the letter A indicates low carbon steel, while the letter B indicates intermediate carbon steel.
The grade designation of alloy structural steels according to the German Institute for Standardization (DIN) is made up of two or three letter symbols, the first two or three of which indicate the type of alloying agent and the last one often indicates the average carbon content expressed as a percentage. For example, the symbols Cr and Mo indicate chromium molybdenum steel, and the symbol C indicates carbon steel.
The grade designation of alloy structural steels according to the Japanese Industrial Standards (JIS) is made up of symbols and numbers. Symbols typically indicate type of alloying agent and, when they are followed by numbers, they indicate average carbon content and/or alloying elements content expressed as a percentage. For example, the codes S25C and S35C indicate low carbon steel and intermediate carbon steel respectively, and the code SCM4 indicates chromium molybdenum steel.
The grade designation of alloy structural steels according to the Chinese Standard for Steel for Building Structures (GB/T 1591-2008) is made up of either a one-, two-, or three-letter symbol and a number. The symbol indicates the type of alloying agent and the number indicates average carbon content and/or alloying elements content expressed as a percentage. For example, the code Q235 indicates low carbon steel, while the code Q345 indicates medium carbon steel.
The grade designation of alloy structural steels according to the European norm (EN 10027) is made up of a letter and a number followed by a period. The letter indicates the type of alloying agent and the number indicates average carbon content and/or alloying elements content expressed as a percentage. For example, the code S355 indicates medium carbon steel, while the code 16MnCr5 indicates chromium manganese steel.
In conclusion, the grade designation of alloy structural steels is an important way for engineers and manufacturers to classify different grades of alloy structural steels. The most common grade designation methods are the American Iron and Steel Institute (AISI) Method, German Institute for Standardization (DIN) Method, Japanese Industrial Standards (JIS) Method, European norm (EN 10027) Method and Chinese Standard for Steel for Building Structures (GB/T 1591-2008) Method.
