EN24 steel, with its impressive strength and durability, has been a reliable choice in various industries for over a century. This alloy steel, composed of nickel, chromium, and molybdenum, offers excellent tensile strength, ductility, and resistance to shock. In this blog post, we delve into the properties and characteristics of EN24 steel, shedding light on its applications, heat treatment, and more.
EN24 Steel: An Overview
EN24 is a well-established steel grade that boasts a long-standing history dating back to the early 1900s. It is a nickel-chrome-molybdenum alloy steel, containing approximately 1.5% nickel, 1% chromium, and 0.2% molybdenum.
This composition allows EN24 to be heat treated to a wide range of tensile strengths, ranging from 850-1000 N/mm² in the ‘T’ condition to an impressive 1550 N/mm² in the ‘Z’ condition.
EN24 Chemical Compositions
| Element | Composition Range |
|---|---|
| Carbon | 0.35-0.45% |
| Silicon | 0.10-0.35% |
| Nickel | 1.30-1.80% |
| Manganese | 0.45-0.70% |
| Chromium | 0.90-1.40% |
| Phosphorous | 0.05% max |
| Molybdenum | 0.20-0.35% |
| Sulphur | 0.05% max |
| Condition. | Tensile Strength (N/mm²) | Yield Strength (N/mm²) | Elongation (%) | Impact (KCV J) | Hardness (Brinell) |
|---|---|---|---|---|---|
| T | 850-1000 | 650 | 13 | 35 | 248-302 |
| U | 925-1075 | 755 | 12 | 42 | 269-331 |
| V | 1000-1150 | 850 | 12 | 42 | 293-352 |
| W | 1075-1225 | 940 | 11 | 35 | 311-375 |
| X | 1150-1300 | 1020 | 10 | 28 | 341-401 |
| Y | 1225-1375 | 1095 | 10 | 21 | 363-429 |
| Z | 1550 | 1235 | 5 | 9 | 444 |
Equivalents of EN24 Steel
Due to its popularity, several countries have developed their own versions of nickel-chrome-moly high tensile steels similar to EN24. For example, in the United States, a comparable alloy is known as 4340, while Germany refers to it as 34CrNiMo6. Other equivalents can be found in France (1.6582), Sweden (34NiCrMo8 / 35NCD6), Spain (14.2541), and Japan (SNCM447 S95 / S119).
Applications of EN24 Steel
EN24 steel found its initial use in the automotive and aerospace industries, where it was employed to produce various components and parts. Today, it remains a popular choice, especially in the manufacturing sector.
Some common applications of EN24 steel include power transmission gears, crankshafts, axles, propeller and gearbox shafts, connecting rods, bolts, and structural components that require high tensile strength and toughness.
EN24 Heat Treatment
EN24 can undergo various heat treatment processes to achieve desired properties. Conventional hardening and tempering involve heating the steel to 830-850°C and then quenching it in oil. Tempering is carried out once the steel reaches room temperature.
For hardening from the ‘T’ condition, a full annealing process is recommended before heat treatment. The standard annealing process involves heating the steel to 840-860°C, cooling it to 580°C in the furnace, and allowing it to cool to room temperature.
Mechanical Properties
EN24 steel demonstrates excellent mechanical properties in different conditions. The tensile strength ranges from 850-1000 N/mm² in the ‘T’ condition to 1550 N/mm² in the ‘Z’ condition. Similarly, the yield strength, elongation, Izod impact values, and hardness vary depending on the specific condition of the steel.
Machinability and Weldability
EN24 steel is machinable both in the annealed condition and when hardened and tempered. However, the machinability is lower compared to mild steel. Welding EN24 steel in its annealed condition is possible, but caution must be exercised when dealing with higher tensile conditions. Welding after hardening treatments is not recommended. Stress relieving is beneficial after welding or extensive cold work.
Conclusion
EN24 steel has proven itself as a durable and high-strength alloy that has stood the test of time. Its impressive combination of tensile strength, ductility, and shock resistance makes it a popular choice in various industries. Whether it’s power transmission gears, crankshafts, or structural components, EN24 steel continues to deliver exceptional performance.