Carbon and alloy steels

• S235
• C45
• 42CrMo4
• 16MnCr5
• 11SMn30

The backbone of general engineering. S235 is a plain structural steel - cheap and forgiving. C45 can be quenched and tempered. 42CrMo4 usually arrives already in the quenched-and-tempered condition, with uniform hardness through the section: it turns predictably, but demands tougher tooling than C45 and punishes a dull edge. 16MnCr5 is a case-hardening steel - machined soft and hardened only at the surface after carburising, so final dimensions are cut before heat treatment with an allowance for grinding. 11SMn30 is a free-cutting steel with sulphur: it cuts easily with short chips and suits large runs of small parts, but it cannot be welded or hardened.

The grades listed are typical of current production - to be confirmed with the client.

State the grade and the condition, not just “steel”. As-rolled 42CrMo4 and quenched-and-tempered 42CrMo4 are turned with different tooling and priced differently. If the part is case-hardened, mark the grinding allowance explicitly and which dimensions are cut before treatment. For 11SMn30, say whether welding or hardening follows: it takes neither, and swapping the grade is cheaper discovered at quotation than at goods-in.

Case-hardening steels - 16MnCr5 is the usual one - have the longest routing: machined soft, carburised, then ground to size. Functional dimensions are cut after treatment; before it they stay with an allowance. Quenched-and-tempered steels arrive already treated and turn straight to size, but they demand a fresh edge: a dull tip does not cut them, it rubs, and the surface shows it immediately.

• Shafts and bearing journals
• Flanges and bushings
• Drivetrain parts
• Hydraulic and pneumatic bodies
• High-volume free-cutting steel parts