440C stainless steel (UNS S44004) is a high-carbon martensitic chromium alloy frequently used where high hardness and wear resistance are important after hardening. Bearing races, precision wear parts, shafts, and machining applications may require careful coordination of heat treatment, dimensional stability, and final grinding.
Download 440C Stainless Steel Round Bar — Mozaic technical reference (PDF)
440C Stainless Steel Round Bar — Technical Specifications
| Property or designation | Reference information |
|---|---|
| Alloy / UNS | 440C / S44004 |
| European comparison | EN 1.4125; confirm purchase standard |
| Relevant bar specification | ASTM A276 where ordered to the bar specification |
| Carbon (C) | 0.95–1.20 wt% |
| Chromium (Cr) | 16.0–18.0 wt% |
| Molybdenum (Mo) | Up to 0.75 wt% in cited grade reference |
| Manganese (Mn) | 1.00 wt% maximum |
| Hardened capability | Up to approximately 60 HRC depending on condition and process |
| Heat-treatment consideration | Distortion, cracking and final finish require controlled processing |
Technical values shown are general reference information, not a mill test report. Chemical limits and mechanical properties are governed by the applicable material specification, heat/lot and supply condition.
Applications and Grade Comparison
440C is selected for high-hardness wear components, bearing applications, and parts exposed to abrasion. It is not interchangeable with 420 stainless steel or free-machining 416 stainless steel. Grade choice depends on attainable hardness, corrosion exposure, and machining route. Read our 440C ASTM A276 guide for specification context.
Precision Centerless Grinding and Bar Preparation
440C can demand grinding process controls appropriate to its supply condition and finished geometry. Provide heat-treated condition, target hardness, starting and finished OD, length, tolerances and surface-finish criteria. Grinding after final heat treatment is often critical for wear components. See Mozaic’s centerless grinding services.
Common Questions
What hardness can 440C reach?
In suitable heat-treated conditions it can approach approximately 60 HRC, but the achievable result depends on the ordered condition and treatment process.
Should 440C be ground before or after hardening?
It depends on allowances and final tolerance. Precision finish grinding is commonly performed after hardening, with distortion allowance considered in process planning.
Request a Quote
For order-specific sourcing and grinding availability, request a quote, email sales@mozaicprecision.com, or call 847-637-8379.
Reference source: technical grade information. This page is not a substitute for the relevant purchase specification or mill certification.