Steel 4130 Plate Prices

About 4130|The weldable chromoly. Same chromium-molybdenum family as 4140 but with 0.30% carbon instead of 0.40%. That lower carbon makes a real difference in weldability and ductility while still giving good strength after heat treatment. This is the aerospace tube and race car chassis steel. 4130 tube is everywhere in aircraft frames, roll cages, and structural fabrication where you need to weld chromoly and trust the joint. Machines well in the annealed condition. Not as strong as 4140 when heat treated because of the lower carbon, so if you're making a shaft or gear that needs maximum hardness, go with 4140 or 4340. But if the part gets welded, 4130 is almost always the better choice. Compare to 4140 (stronger but harder to weld) and 1045 (cheaper, similar strength range but no alloy content for hardenability in thick sections).

About Plate|Thick flat stock, generally 3/16" and up, used for machined base plates, fixture plates, wear surfaces, and structural fabrication. Heavier grades get milled, drilled, and tapped directly.