Table of Contents
What is 420 Stainless Steel PM Material?
420 stainless steel is a martensitic stainless steel that can be hardened by heat treatment to achieve high hardness (50-55 HRC) while maintaining moderate corrosion resistance. It's the workhorse material for cutting tools, knives, and wear-resistant components.
Material Designation
- AISI: 420
- UNS: S42000
- Type: Martensitic (hardenable) stainless steel
Chemical Composition
| Element | Weight % |
|---|---|
| Chromium (Cr) | 12-14% |
| Carbon (C) | 0.15-0.40% |
| Manganese (Mn) | <1% |
| Silicon (Si) | <1% |
| Iron (Fe) | Balance |
Key: Higher carbon content (vs 304/316L) enables hardening via heat treatment.
Mechanical Properties
Annealed Condition
| Property | Typical Value |
|---|---|
| Hardness | 85-95 HRB (~20 HRC) |
| Tensile Strength | 550-650 MPa (80-95 ksi) |
| Yield Strength | 350-450 MPa (51-65 ksi) |
| Elongation | 15-20% |
Hardened & Tempered (Oil Quenched)
| Property | Typical Value |
|---|---|
| Hardness | 50-55 HRC |
| Tensile Strength | 1700-1900 MPa (247-276 ksi) |
| Yield Strength | 1400-1600 MPa (203-232 ksi) |
| Elongation | 2-5% |
Density: 6.8-7.2 g/cm3 (PM), 7.7 g/cm3 (wrought)
Heat Treatment
Hardening Process
- Austenitize: 1010-1065°C (30 min)
- Quench: Oil (air quench for lower hardness)
- Temper: 150-370°C (1-2 hours)
- 150°C ->54-56 HRC (maximum hardness)
- 260°C ->50-52 HRC (better toughness)
- 370°C ->45-48 HRC (maximum toughness)
Cooling: Air cool after tempering
Key Advantages
- High Hardness - Up to 55 HRC after heat treatment
- Good Corrosion Resistance - Better than carbon steel, not as good as 304/316L
- Wear Resistance - Excellent for cutting edges and sliding surfaces
- Moderate Cost - Cheaper than 17-4PH or 440C
- Magnetic - Can be used in magnetic assemblies
Typical Applications
Cutting Tools
- Knife blades
- Scissors and shears
- Surgical scalpels
- Cutting inserts
Wear-Resistant Components
- Valve seats and stems
- Pump plungers
- Nozzles and orifices
- Wear plates
Industrial Parts
- Ball bearings (races)
- Hardened bushings
- Dowel pins
- Precision springs (heat treated)
Automotive
- Fuel injector components
- Brake system parts
- High-wear fasteners
Corrosion Resistance
Good Against:
- Atmospheric corrosion
- Mild acids (dilute)
- Alkaline solutions
- Dry environments
Limited Against:
- Chlorides (will pit)
- Strong acids
- Salt spray
Note: Corrosion resistance decreases as hardness increases (tempering temperature matters).
Processing Parameters
- Compaction Pressure: 650-800 MPa
- Sintering Temperature: 1250-1300°C
- Sintering Atmosphere: Vacuum or high-purity hydrogen
- Sintering Time: 30-60 minutes
- Green Density: 6.5-7.0 g/cm3
Post-Sinter: Heat treatment required to achieve full properties.
Design Considerations
Suitable For:
High hardness requirements (>50 HRC) Cutting and wear applications Moderate corrosion environments Magnetic applications
Not Suitable For:
鉂?Marine/chloride environments (use 316L) 鉂?Non-magnetic applications (use 304) 鉂?High-impact loading (brittleness at max hardness)
Material Comparison
| Material | Max Hardness | Corrosion Resistance | Cost | Best For |
|---|---|---|---|---|
| 420 SS | 55 HRC | Good | $$$ | Cutting tools, wear parts |
| 440C SS | 60 HRC | Very Good | $$$$ | Premium knives, bearings |
| 17-4PH SS | 44 HRC | Excellent | $$$$ | Aerospace, high-strength |
| 410 SS | 45 HRC | Good | $$ | General hardened parts |
| D2 Tool Steel | 62 HRC | Fair | $$$$ | High-wear tooling |
Secondary Operations
Required:
- Heat treatment (hardening + tempering)
- Grinding (precision after hardening)
Common:
- Polishing (for cutting edges)
- Passivation (improve corrosion resistance)
- Cryogenic treatment (improve wear resistance)
Optional:
- Coating (TiN, DLC for extreme wear)
Cost Estimate
Material Cost: $12-20/kg (powder) Processing Cost: High (vacuum sintering + heat treatment) Typical Part Cost: 2-4x carbon steel PM parts
Cost Drivers:
- Chromium content
- Vacuum/high-purity atmosphere sintering
- Heat treatment required
Quality Standards
- ASTM A756 - Stainless Steel PM Structural Parts
- MPIF Standard 35 - PM Stainless Materials
- AMS 5610 - Aerospace 420 Stainless (wrought, reference)
Get 420 Stainless Steel PM Parts from SinterWorks
SinterWorks produces 420 SS PM components with:
- In-house heat treatment (50-55 HRC capability)
- Vacuum sintering for clean parts
- Precision grinding after hardening
- Hardness testing and certification
Request a quote: Contact us for hardened stainless steel PM parts.
Frequently Asked Questions
What is the maximum hardness achievable?
54-56 HRC with proper heat treatment and carbon content ~0.35-0.40%.
Can 420 SS be welded?
Yes, but requires preheating (200-300°C) and post-weld heat treatment to avoid cracking.
Is 420 SS food-safe?
It is used in cutting and wear components for food-processing equipment, but final suitability depends on end use, surface finish, cleaning method, and customer compliance requirements.
How does it compare to 440C?
440C has higher carbon and chromium, achieving 58-60 HRC with better corrosion resistance, but costs 30-50% more.
Related Resources
Use these internal links to keep moving through the most relevant guides, service pages, and technical references for this topic.
410 Stainless Steel PM
Compare 420 with a lower-cost martensitic stainless PM route when you need moderate corrosion resistance with lower hardness demand.
17-4 PH Stainless Steel PM
Review a higher-strength stainless PM option when precipitation hardening and better structural performance matter more than maximum hardness.
Valve Components
See where hardenable stainless PM materials fit valve, pump, and wear-sensitive flow-control hardware.
Request a Quote
Send your hardness target, corrosion environment, and geometry for 420 stainless PM review and quotation support.