8740 Alloy Steel Round Bar: 8740 is a nickel-chromium-molybdenum low-alloy steel used for mechanical components requiring controlled hardness and toughness after appropriate treatment.
Download Mozaic 8740 Alloy Steel Round Bar technical reference PDF
8740 Alloy Steel Round Bar — Technical Overview
| Specification item | Reference or order requirement |
|---|---|
| Grade or product | 8740 Alloy Steel Round Bar |
| Material designation / identity | SAE/AISI 8740 / UNS G87400; Ni-Cr-Mo alloy steel |
| Specification to review | ASTM A29/A29M and any relevant aerospace or procurement spec |
| Delivery/heat-treatment condition | Identify annealed/normalized or quenched-and-tempered condition |
| Examples of applications | Fasteners, mechanical shafts and high-strength machined parts |
| 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
8740, 4140 and 4340 differ in alloy content and hardenability; choose from design requirements. Representative applications include fasteners, mechanical shafts and high-strength machined parts. 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
- 4340 steel — related but not automatically interchangeable
- 4140 round bar 2 — related but not automatically interchangeable
Common Buyer Questions
What condition must be specified for 8740 Alloy Steel Round Bar?
Identify annealed/normalized or quenched-and-tempered condition. If the condition is not on the drawing, request the engineer’s confirmation before ordering or machining.
Are nearby grades automatic equivalents?
No. 8740, 4140 and 4340 differ in alloy content and hardenability; choose from design requirements. 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.