420F Free-Machining Stainless Round Bar — 420F (UNS S42020) is a sulfur-modified, hardenable martensitic stainless grade selected for automatic machining. Compared with ordinary 420, the free-machining composition changes corrosion, weldability and polishing behavior.
Download 420F Free-Machining Stainless Round Bar technical reference sheet (PDF)
420F Free-Machining Stainless Round Bar — Grade and Specification Information
| Item | Details |
|---|---|
| Grade / material designation | 420F Free-Machining Stainless Round Bar |
| Chemistry / identity | Chromium 12.0–14.0 wt%; grade-specific sulfur and carbon limits must match the mill certificate |
| Applicable specification to confirm | Check ASTM A582 or specified AMS requirements for the actual product |
| Supply condition | Annealed or hardened and tempered; verify hardness and supply state |
| Typical component applications | Turned valve parts, precision mechanical components and parts requiring further hardening |
| Finished bar processing | Customer-defined outside diameter, tolerance, straightness and surface finish; actual capability is project-specific |
The table provides grade-level background, not certified mechanical or chemical values for a particular heat. Verify the governing standard, supplied condition and mill test report.
Material Selection and Limitations
Avoid treating 420F and 420 as equivalent when service requires pressure containment, corrosion resistance or mirror polishing.
Before purchasing, confirm whether the job calls for corrosion resistance, hardness, strength, machinability, elevated-temperature performance, or dimensional stability. Matching only a similar material name does not establish engineering interchangeability. A design engineer should approve any substitutions against the drawing and the customer-required specification.
Industrial Applications and Precision Processing
420F Free-Machining Stainless Round Bar is used for turned valve parts, precision mechanical components and parts requiring further hardening. At Mozaic Precision Metals, we review requests for centerless grinding, straightening, polishing, chamfering, saw cutting and protective packaging based on the grade’s condition and the required bar dimensions. Exact stock availability, OD tolerance and finish capability are quoted case by case.
Related Stainless Steel and Alloy Grades
- 420 stainless steel — a related grade with distinct service or processing characteristics
- 416 stainless steel — a related grade with distinct service or processing characteristics
Request a 420F Free-Machining Stainless Round Bar Quote
Include the exact designation and product specification, annealed or heat-treated condition, starting diameter and required finished OD, length, quantity, straightness requirement, surface roughness, and material certifications. Request pricing and availability; email sales@mozaicprecision.com or call 847-637-8379.
Grade reference: related technical or qualification resource. For purchasing decisions, the current specification and mill documentation govern.