The 42CrMo4 type of steel is used for tempering and quenching, in part because it has such a good combination of toughness and strength in the tempered and quenched condition. Once the oil quenching is complete, the steel itself will be through-hardened up to ø60 mm bar diameter. The steel itself is applicable to induction hardening. This is a special high-grade steel that provides a great amalgamation of both toughness and strength, and it is usually available in a mix of microstructure, that is, austenite and martensite. There are different European standards that cover the specification of the steel in various forms and processing conditions. The special grade of this steel is always subjected to M-treatment to provide the best machinability properties.

The 42CrMo4 type of alloy steel has a chemical composition that looks like this:

• C: 0.38-0.45%
• Cr: 0.90-1.20%
• Mn: 0.60-0.90%
• Mo: 0.15-0.30%
• P: 0.035%
• S: 0.035%
• Si: 0.40% max.

In addition, these steels are sold on the global market as per various European standards, including steel tubes, steel die forgings, cold redrawn forms, cold-rolled narrow steel strips, seamless circular steel tubes, flat plates, and rods, wires, and bars. They are even available in round bar sizes 10 to 3000 mm in diameter and in flat plates with a thickness of 10 to 1500 mm and a width of 200 to 3000 mm, as well as other steel sizes and shapes that you can have custom made.

For the alloy steel manufacturer that makes the 42CrMo4 type of steel, they know that this high-grade steel has low weldability but can be welded when friction is used. Of course, you still have to take precautions so there are no unwanted weakening microstructures in the weld zone.