Introduction
Steel as a material has a variety of grades, forming large classifications that help people differentiate between different types of steel according to their properties. The steel grade system is a hierarchical system of classification designed to separate different steel types based on their inherent characteristics. Each country has its own steel grade designation system and its steel grade designation systems are different from each other. This article provides an overview of steel grade designation systems in Japan, the United Kingdom, and France and how they differ.
Japan
The Japan Iron and Steel Federation (JISF) is responsible for developing and maintaining the steel grade designation system used in Japan. JISF classifies steel grades into three major groups: Structural Steel, which includes general purpose and low alloy steels; Automotive Steel, which includes steels used in the automotive industry and; Special Steel, which includes steels for cutting tools, bearing steels, and springs.
JISF has a comprehensive classification system for steel grades and assigns each grade a unique four-digit code. The first digit in a JISF steel grade indicates the type of steel. For example, the first digit of three indicates that it is a structural steel, the first digit five indicates an automotive steel, and the first digit nine indicates special steel. The second and third digits indicate the alloying element composition and the last digit indicates a unique combination which adds to the overall grade of the steel.
United Kingdom
In the United Kingdom, the British Standards Institution (BSI) is responsible for developing, maintaining, and updating the steel grade designation system. The designation system used in the UK is the BS steel designation system which has nine grades of steel. The first two digits of the designation indicate the type of steel. The letter X refers to high-yield structural steel, the letter P refers to alloy steel, and the letter S refers to stainless steel. The number that follows the letter indicates the steel grade, with higher numbers corresponding to higher strength grades.
The fourth digit indicates the minimum yield strength and the fifth digit indicates the Porosity Index. The Porosity Index indicates the susceptibility to hydrogen embrittlement and indicates the corrosion resistance of the steel. The sixth digit indicates the condition of the steel and the final two digits indicate the product form and the thickness of the sheet.
France
The classification of steel in France is based on the NF A35-521 standard, which is maintained by the Association Francaise de Normalisation (AFNOR). This standard contains approximately 200 steel grades. The designation system used in France uses a three-digit code to indicate the steel grade. The first two digits indicate the type of steel while the third digit indicates the strength grade.
The first digit of the designation is used to identify the type of steel. This digit can be zero, six, or seven, with zero indicating carbon steel, six indicating alloy steel, and seven indicating stainless steel. The second digit indicates the strength grade, with higher numbers indicating higher strength. The third digit is reserved for additional information related to the steel grade. For example, the first three digits of the designation for A-36 steel are 060, which indicates that it is a carbon steel with a strength grade of 36.
Conclusion
In conclusion, each country has developed its own classification system for steel grades which helps people differentiate between different types of steel according to their properties. In Japan, the Japan Iron and Steel Federation is responsible for developing and maintaining the steel grade designation system. In the UK, the British Standards Institution is responsible for developing and maintaining the designation system. In France, the Association Francaise de Normalization is responsible for the classifications of steel in France. Each designation system is different and the classification of steel varies between countries.
