4140 Alloy Steel Round Bar: 4140 is a medium-carbon chromium-molybdenum alloy steel commonly supplied annealed or quenched-and-tempered for shafts and demanding precision-machined components.
Download Mozaic 4140 Alloy Steel Round Bar technical reference PDF
4140 Alloy Steel Round Bar — Technical Overview
| Specification item | Reference or order requirement |
|---|---|
| Grade or product | 4140 Alloy Steel Round Bar |
| Material designation / identity | SAE/AISI 4140 / UNS G41400; Cr-Mo steel |
| Specification to review | ASTM A29/A29M or particular Q&T steel bar specification |
| Delivery/heat-treatment condition | Specify annealed or Q&T condition and mechanical acceptance limits |
| Examples of applications | Drive shafts, pins, machine components and high-strength hardware |
| Quotation and inspection | Provide OD, length, finished tolerance, surface finish and heat-lot documents |
Engineering reference, not a mill test report. Actual chemistry, properties, condition, availability and qualification must meet the ordered product specification and accompanying certification.
Material Properties, Typical Parts and Selection
4140 is not the same as leaded 41L40; avoid treating the two grade designations as synonyms. Representative applications include drive shafts, pins, machine components and high-strength hardware. Suitability depends on the environment, grade, geometry, strength/temper and processing route. Specify finished-size and material performance separately; two alloys with similar commercial names may have different test standards.
Precision Grinding, Straightening and Bar Finishing
Mozaic Precision Metals supports project-specific bar sourcing and centerless grinding, straightening, polishing, cutting, chamfering and packaging. Describe the incoming and finished OD, bar length, drawing requirements, production quantity and material traceability. Surface roughness, diameter tolerance and straightness are independent acceptance characteristics, and actual capability is confirmed by quote.
Related Grades and Application Alternatives
- 4130 alloy steel — related but not automatically interchangeable
- 4340 steel — related but not automatically interchangeable
Common Buyer Questions
What condition must be specified for 4140 Alloy Steel Round Bar?
Specify annealed or Q&T condition and mechanical acceptance limits. If the condition is not on the drawing, request the engineer’s confirmation before ordering or machining.
Are nearby grades automatic equivalents?
No. 4140 is not the same as leaded 41L40; avoid treating the two grade designations as synonyms. Mechanical-property and chemical compliance must be verified against the applicable specification and mill certification.
Request a Quote
Email sales@mozaicprecision.com, call 847-637-8379, or request pricing and availability online.