MIM-304 Stainless Steel
MIM-304 is the most widely used austenitic stainless steel in Metal Injection Molding (MIM). Known for its excellent balance of corrosion resistance, formability, and cost-effectiveness, MIM-304 serves as the go-to material for general industrial, food processing, and consumer electronics applications where extreme chloride resistance is not required.
At Emitech, we produce precision MIM-304 components with consistent quality across high-volume production runs. Our MIM-304 parts achieve near-full density with mechanical properties matching wrought 304 stainless steel, enabling complex geometries at a lower cost per part than CNC machining or investment casting.
Material Characteristics
MIM-304 combines the benefits of austenitic stainless steel with the design freedom of metal injection molding. Key characteristics include:
- Good corrosion resistance — Protects against atmospheric, chemical, and food-grade environments
- Non-magnetic — Retains austenitic structure after sintering, suitable for electronic enclosures
- Excellent formability — Achieves complex shapes with thin walls and internal features
- Cost-effective — Lower raw material cost than 316, ideal for high-volume consumer products
- Easy to clean and sterilize — Smooth surfaces meet hygiene standards for food and medical equipment
- Wide temperature range — Serviceable from cryogenic temperatures up to 800°C
Chemical Composition
The typical chemical composition of MIM-304 powder conforms to ASTM A240 and MPIF Standard 35:
| Element | Weight % (min-max) |
|---|---|
| Iron (Fe) | Balance |
| Chromium (Cr) | 18.0 - 20.0 |
| Nickel (Ni) | 8.0 - 10.5 |
| Carbon (C) | ≤ 0.08 |
| Manganese (Mn) | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.03 |
Physical & Mechanical Properties
| Property | Value |
|---|---|
| Density (sintered) | ≥ 7.8 g/cm³ |
| Tensile Strength | ≥ 515 MPa |
| Yield Strength | ≥ 205 MPa |
| Elongation | ≥ 30% |
| Hardness (HV) | 120 - 180 |
| Young's Modulus | 193 GPa |
| Thermal Expansion | 17.2 μm/m·K (20-100°C) |
| Max Service Temperature | 800°C (intermittent) |
MIM-304 vs MIM-316 Comparison
Selecting between 304 and 316 depends on your application's environmental demands and budget:
| Feature | MIM-304 | MIM-316 |
|---|---|---|
| Corrosion Resistance | Good (general purpose) | Superior (marine/chemical) |
| Molybdenum (Mo) | None | 2.0 - 3.0% |
| Chloride Resistance | Moderate | Excellent |
| Raw Material Cost | Lower (~20-30% less) | Higher |
| Magnetic Response | Non-magnetic | Non-magnetic |
| Typical Applications | Food, consumer, general industrial | Medical, marine, chemical |
For detailed mechanical data on the 316 family, see our 316/316L stainless steel yield strength guide with full property tables.
Typical Applications
MIM-304 is the workhorse stainless steel for cost-sensitive applications requiring corrosion resistance:
- Food processing equipment — Mixer blades, nozzles, valve seats, pump components
- Consumer electronics — Laptop hinges, phone buttons, wearables enclosures
- Automotive — Sensor housings, decorative trim, clamp rings
- General industrial — Fasteners, brackets, couplings, fittings
- Household appliances — Coffee machine parts, dishwasher components, lock mechanisms
- Medical instruments — Non-implant surgical tools, instrument handles, trays
Why Choose Emitech for MIM-304 Parts?
- Competitive pricing on high-volume MIM-304 production runs
- DFM expertise to optimize part design for MIM-304 processing
- Tight tolerances — ±0.3% to ±0.5% maintained consistently
- Fast tooling — 15-20 day tooling turnaround for new projects
- Surface finishing — Passivation, electropolishing, bead blasting, PVD coating
- Quality assurance — CMM inspection, metallographic analysis, mechanical testing
Frequently Asked Questions
Q: When should I choose MIM-304 over MIM-316?
A: Choose MIM-304 when your application does not expose parts to chlorides, saltwater, or aggressive chemicals. For general industrial, food processing, and consumer electronics, 304 offers the best cost-performance ratio. Upgrade to 316 only when superior chloride resistance is mandatory.
Q: Is MIM-304 magnetic?
A: In its as-sintered austenitic condition, MIM-304 is non-magnetic. However, cold working or severe deformation can induce a small amount of martensite, resulting in slight magnetic response. For applications requiring absolute non-magnetic properties, specify MIM-316L or consult our engineering team.
Q: Can MIM-304 be used for food contact applications?
A: Yes. MIM-304 meets FDA requirements for food contact materials. The dense, pore-free structure achieved through MIM sintering eliminates the risk of bacterial growth in surface defects, making it safer than porous cast or partially dense PM parts for food and beverage equipment.
Q: What is the difference between 304 and 304L in MIM?
A: MIM-304L is the low-carbon variant with maximum 0.03% carbon (vs 0.08% for standard 304). The reduced carbon content prevents sensitization and intergranular corrosion in welded assemblies. For MIM parts that will not be welded, standard 304 is sufficient and slightly more economical.
Q: How does the cost of MIM-304 compare to CNC machined 304?
A: For complex geometries in volumes above 5,000 pieces annually, MIM-304 typically costs 30-50% less per part than CNC machining. The savings increase with part complexity, as MIM produces net-shape components requiring minimal secondary operations.
Q: What surface finishes are available for MIM-304?
A: MIM-304 responds well to all standard stainless steel finishing processes. Common options include passivation (ASTM A967), electropolishing for ultraclean surfaces, bead blasting for matte texture, PVD coating for color, and vibratory finishing for edge deburring. We recommend passivation for all MIM-304 parts to restore the protective oxide layer.
Q: What is the minimum order quantity (MOQ) for MIM-304 parts?
A: Our typical MOQ for MIM-304 is 5,000 pieces per year or a tooling investment equivalent. For prototype quantities, we offer soft tooling options at reduced cost. Contact us with your annual volume forecast and we will recommend the most cost-effective production strategy.
Q: Can MIM-304 parts be welded after sintering?
A: Yes, MIM-304 can be welded using TIG, MIG, or laser welding methods. However, the heat-affected zone may cause sensitization in standard 304. For welded assemblies, we recommend specifying MIM-304L or applying a post-weld solution anneal to restore corrosion resistance.
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