Bearing Steel Grades
Bearing steel refers to a type of alloy steel used in rolling contact bearings, such as those found in ball and roller bearings. Bearing steels are designed to have high reliability and durability, even in extreme operating conditions. They generally contain a high proportion of chromium and other alloying elements, and must be heat-treated in order to realize their maximum hardness and optimal tribological properties in a bearing application. As such, bearing steels usually adhere to a specific grade system, to ensure consistent quality and performance.
Common Bearing Steel Grades
The most common bearing steel grade systems used in the world are the American ASTM A295 and A485, the European ISO 683-17, the Japanese JIS G4805, and the Chinese GB/T 18254 grade systems. Each grade system might have a few common grades in it, and each grade will have its own performance characteristics. For example, the A485 grade system has three grades – 52100, E52100, and 100Cr6 – while the JIS grade system has five different grades – SUJ2, SUJ3, SUJ4, SUJ5, and SUJ6.
ASTM A295 Grade System
The American ASTM A295 grade system is one of the most popular bearing steel grade systems, and includes five grades: 52100, E52100, 52100/100Cr6, 52100/EN31, and E52100/EN31. Each grade of steel is designed to have a certain combination of properties, most notably hardness and wear resistance, in order to meet certain application requirements.
Grade 52100 is typically used in automotive applications, as well as most industries requiring a light weight, highly wear resistant steel bearing. It typically has 0.98-1.10% carbon content, 1.30-1.60% chromium content, and up to 0.25% manganese content. It is melted using either an electric furnace or vacuum furnace, and then quenched and tempered to achieve the desired hardness.
E52100 is typically used in extremely heavy duty applications such as aircraft and heavy machinery bearing. It typically has 1.00-1.25% carbon content, 1.40-1.65% chromium content, and up to 0.30% manganese content. It is melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The 52100/100Cr6 grade is a combination of two popular bearing steel grades – 52100 and 100Cr6. This grade typically has 0.95-1.10% carbon content, 1.30-1.60% chromium content, and up to 0.25% manganese content. It is also melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The 52100/EN31 grade is another combination of popular bearing steel grades – 52100 and EN31. This grade typically has 0.85-0.95% carbon content, 1.50-1.75% chromium content, and up to 1.00% manganese content. It is melted using either an electric furnace or a vacuum furnace, and then quenched and tempered to achieve the desired hardness.
E52100/EN31 is a combination of the two grades E52100 and EN31. This grade typically has 0.90-1.05% carbon content, 1.50-1.75% chromium content, and up to 1.00% manganese content. It is melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
ISO 683-17 Grade System
The European ISO 683-17 grade system is a popular bearing steel grade system, and it includes four main grades: 100Cr6, 100CrMn6-1-4, 100CrMo7, and 100CrMo7-3. Each grade of steel is designed to have a certain combination of properties, most notably hardness and wear resistance, in order to meet certain application requirements.
Grade 100Cr6 is typically used in automotive applications, as well as most industries requiring a light weight, highly wear resistant steel bearing. It typically has 0.93-1.05% carbon content, 1.40-1.60% chromium content, and up to 0.30% manganese content. It is melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The 100CrMn6-1-4 grade is typically used in moderately heavy duty applications, such as agricultural equipment and some industrial machinery. It typically has 0.98-1.10% carbon content, 1.50-1.70% chromium content, and up to 0.30% manganese content. It is also melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The 100CrMo7 grade is typically used in heavy-duty applications, such as large industrial machinery and aircraft applications. It typically has 1.00-1.25% carbon content, 1.40-1.65% chromium content, and up to 0.30% manganese content. It is melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The 100CrMo7-3 grade is a higher performance version of the 100CrMo7 grade, and is typically used in very heavy-duty applications, such as astronautics, heavy-duty drilling, and gear transmissions. It typically has 1.20-1.35% carbon content,1.60-1.80% chromium content, and up to 0.30% manganese content. It is also melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
JIS G4805 Grade System
The Japanese JIS G4805 grade system is a popular bearing steel grade system, and it includes five grades: SUJ2, SUJ3, SUJ4, SUJ5, and SUJ6. Each grade of steel is designed to have a certain combination of properties, most notably hardness and wear resistance, in order to meet certain application requirements.
Grade SUJ2 is typically used in moderately light duty applications, such as automotive and some industrial machinery. It typically has 0.95-1.05% carbon content, 1.30-1.60% chromium content, and up to 0.25% manganese content. It is melted using either an electric furnace or a vacuum furnace, and then quenched and tempered to achieve the desired hardness.
The SUJ3 grade is typically used in moderately heavy duty applications, such as most industrial machinery and some agricultural equipment. It typically has 1.00-1.10% carbon content, 1.50-1.75% chromium content, and up to 0.30% manganese content. It is also melted using either an electric furnace or a vacuum furnace, and then quenched and tempered to achieve the desired hardness.
The SUJ4 grade is typically used in heavy-duty applications, such as large industrial machinery and some aircraft applications. It typically has 1.10-1.20% carbon content, 1.60-1.80% chromium content, and up to 0.30% manganese content. It is melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The SUJ5 grade is a higher performance version of the SUJ4 grade, and is typically used in very heavy-duty applications, such as astronautics, heavy-duty drilling, and gear transmissions. It typically has 1.20-1.30% carbon content, 1.70-1.90% chromium content, and up to 0.30% manganese content. It is also melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The SUJ6 grade is the highest performance grade in the JIS grade system, and is typically used in the toughest of applications, such as large and powerful locomotives and marine vessels. It typically has 1.30-1.45% carbon content, 1.90-2.10% chromium content, and up to 0.30% manganese content. It is melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
GB/T 18254 Grade System
The Chinese GB/T 18254 grade system is a popular bearing steel grade system, and it includes five grades: 100Cr6, 45CrNiMo6, 100CrMnSi, 40CrNiMoA, and 50CrNiMoA. Each grade of steel is designed to have a certain combination of properties, most notably hardness and wear resistance, in order to meet certain application requirements.
Grade 100Cr6 is typically used in automotive applications, as well as most industries requiring a light weight, highly wear resistant steel bearing. It typically has 0.93-1.05% carbon content, 1.40-1.60% chromium content, and up to 0.30% manganese content. It is melted using an electric arc furnace, and then quenched and tempered to achieve the desired hardness.
The 45CrNiMo6 grade is typically used in moderately heavy duty applications, such as agricultural equipment and some industrial machinery. It typically has 0.98-1.10% carbon content, 1.40-1.60% chromium content, and up to 0.30
