This guide provides general procurement information. The approved drawing, material standard, quotation and purchase specification control each order.
Do not order by an assumed equivalent
Specify EN19 or AISI/SAE 4140 with the exact governing standard, revision, dimensions, supply condition, heat treatment, property requirements and inspection plan.
Why the names are compared
Both designations are used for chromium-molybdenum alloy steels associated with shafts, gears, drive components and heavy engineering. However, the designation alone does not control every chemistry limit, delivery condition or test requirement.
What the purchase order should control
| Area | Required buyer decision |
|---|---|
| Designation | EN19 or AISI/SAE 4140, plus the governing material standard and revision. |
| Dimensions | Diameter, length, tolerance, straightness and machining allowance. The published round-bar range is 25 mm to 66 mm. |
| Condition | As-rolled, normalized, annealed, quenched and tempered, or another specified condition. |
| Properties | Required hardness, tensile, yield, impact or other acceptance values where applicable. |
| Inspection | Chemistry, mechanical testing, surface and internal inspection, traceability and MTC scope. |
Questions to resolve before accepting an equivalence proposal
- Which standard legally or contractually controls the component?
- Are the chemistry limits acceptable across the ordered section size?
- Which supply condition and heat-treatment route apply?
- Which mechanical values and test locations control acceptance?
- Is customer or third-party approval required before substitution?
Applications and order definition
For shafts, gears, machined parts and forged components, send the component drawing and downstream process with the material request. This helps connect the offered grade, bar condition, machining allowance and inspection scope to the final use.
Related alloy steel resources
Review alloy steel round bars, the alloy round-bar buying guide and the quality assurance framework.
Frequently asked questions
Is EN19 identical to AISI 4140?
No automatic identity should be assumed. They are commonly cross-referenced, but the governing standard, chemistry, condition, properties and inspection requirements must be checked for the order.
Which 4140 round bar sizes are published?
The site publishes a general round-bar diameter range of 25 mm to 66 mm. Grade-size-condition availability is confirmed for each enquiry.
What should a 4140 round bar enquiry include?
Include the AISI/SAE 4140 designation, governing standard, diameter, length, tolerance, condition, quantity, application, heat treatment, testing and delivery destination.
Can EN19 be proposed against a 4140 requirement?
Only after the controlling specifications and acceptance values have been compared and the buyer has approved the proposal.
Send a complete requirement
Use the EN19 and 4140 round bar enquiry page and include the grade, standard, dimensions, condition, quantity, testing, documentation and delivery destination.