Custom parts
Choose the grade and condition together: 1018 and 4140 prehard are not interchangeable stock.
Material overview
Steel is a broad family. KRC’s current online options include 1018 mild steel and 4140 prehardened steel. 1018 is useful for many general mechanical components. 4140 prehard is an alloy steel supplied in a harder condition for suitable strength and wear-related applications. The actual stock condition governs the properties.
Where it fits
Use 1018 for straightforward spacers, blocks, mounting parts, and weldment-related details where its properties fit. Use 4140 prehard when the design requires its higher-strength stock condition. Neither name alone guarantees a specific final hardness or heat-treatment certificate.
Design considerations
Steel is heavier than aluminum and can require more cutting effort. Small deep features and thin webs add difficulty. Unprotected carbon and alloy steels can rust; the service environment may require a coating or other protection. Coatings can alter fitted dimensions and thread behavior.
KRC ordering route
The current selector describes 4140 PH as stock-dependent HRC 25–35. If hardness is functional, define the accepted range on the drawing. Additional heat treatment or finishing is a separate scope item rather than an automatic consequence of choosing steel.