Carbon steel is where many functional parts start: it is inexpensive, strong, easy to weld and easy to machine. The trade-off is corrosion, so the finish is part of the specification rather than an afterthought.
Selecting a grade
- 1018 — low-carbon, general purpose. Machines and welds easily; used for brackets, plates and simple turned parts.
- 1045 — medium-carbon, used where moderate strength and wear resistance matter. Hardens well.
- 4140 — chromoly alloy steel for shafts, gears and high-load parts, usually specified in the pre-hardened state (28–32 HRC) for a balance of strength and machinability.
- Structural grades (S355, A36) — for fabricated frames and weldments, cut and welded rather than precision machined.
Finishing for corrosion
Zinc plating is the most economical protection for machined steel parts; powder coating is preferred for fabricated assemblies with large surface areas; black oxide is used where the part needs a functional dark appearance with light oil protection.
Welded fabrications are normally coated after weld dressing, and we will advise where masking is needed for threads, bores and mating faces.