1. Introduction
The Cr-Mo steel 30Cr4 is a low alloy chromium-molybdenum steel that exhibits high strength, hardenability and toughness in both elevated and ambient temperatures. 30Cr4 is a popular choice in the automotive, mining and construction industries because of its ability to resist wear, corrosion and fatigue due to its improved chromium content. 30Cr4 has good machinability, giving the user greater control in the machining process resulting in better finished products.
2. Properties
30Cr4 has a carbon range of 0.28-0.34%, a manganese content of 1.10-1.40%, a chromium content of 0.90-1.20%, a molybdenum content of 0.15-0.25%, and a phosphorus content of less than 0.030%. It has a yield strength of 655 MPa, a tensile strength of 798 MPa, and a hardness of 42-47 HRb. The steel is fairly easy to machine and the user can expect to gain a good surface finish.
3. Applications
30Cr4 is a great choice for load-bearing and wear-resistant applications due to its high strength, hardness and toughness. It is commonly used in the automotive, construction and mining industries. 30Cr4 can be used to make components like gears, shafts, bolts, axles, springs, and bearings. The steel is also popular in the manufacturing of molds and dies. 30Cr4 is also used in machinery parts where corrosion resistance or an increased electrical conductivity is necessary.
4. Heat Treatment
Heat treatment is an important part of the manufacturing process of 30Cr4 and involves heating it to a specific temperature and allowing it to cool in order to achieve its desired properties. Heat treating 30Cr4 involves a process of heating it to a particular temperature, then quenching it in a liquid or gas medium to partially harden it. This hardened structure can then be further strengthened by tempering at a slightly lower temperature.
5. Weldability
30Cr4 can be welded easily and it exhibits good weldability for a medium manganese steel. The most common welding method for 30Cr4 is Shielded Metal Arc Welding (SMAW), though other welding methods may be used depending on the application. Preheating and post-weld stress relieving may also be needed in order to ensure the joint’s strength and integrity.
6. Heat Resistance
30Cr4 has excellent resistance to oxidation at high temperatures up to 1000℃. It also has good creep resistance and oxidation resistance making it suitable for applications in both elevated and ambient temperatures.
7. Corrosion Resistance
30Cr4 has good corrosion resistance in environments of low to moderate corrosion. It is also highly resistant to corrosion fatigue.
8. Conclusion
30Cr4 is a popular chromium-molybdenum steel with a low alloy content that exhibits high strength, hardenability and toughness. It has excellent heat resistance and good corrosion resistance in environments of low to moderate corrosion. The steel is also relatively easy to machine and weld. 30Cr4 is a popular choice for applications in the auto, construction and mining industries as parts like gears, axles, shafts, springs and bearings.
