MIM Material Selection Guide
Choosing the right material for your metal injection molding (MIM) part is the single most important design decision you will make. It determines mechanical properties, corrosion resistance, magnetic behavior, sintering parameters, and cost. This guide covers every standard MIM material Emitech works with — organized by property, application, and trade-off.
Free MIM Material Selection Checklist
Not sure which alloy fits your application? Send us your part drawing and our metallurgists will recommend the optimal MIM material with a DFM review — within 24 hours.
Stainless Steel MIM Materials
Stainless steels account for roughly 60-70% of all MIM production. They offer a well-rounded balance of strength, corrosion resistance, and affordability.
Austenitic Stainless Steels: 316L and 304
| Property | MIM 316L | MIM 304 |
|---|---|---|
| Density (sintered) | 7.80 g/cm³ (≥96% theoretical) | 7.75 g/cm³ (≥95% theoretical) |
| Yield Strength | 170–205 MPa (annealed) | 205–240 MPa (annealed) |
| Ultimate Tensile Strength | 480–520 MPa | 520–620 MPa |
| Elongation | 40–50% | 45–55% |
| Hardness | 70–90 HRB | 75–90 HRB |
| Corrosion Resistance | Excellent (chloride/pitting resistance via Mo) | Good (general atmospheric) |
| Magnetic? | Non-magnetic (slightly magnetic after cold work) | Non-magnetic (slightly magnetic after cold work) |
| Sintering Temperature | 1,300–1,360°C (H₂/N₂ atmosphere) | 1,300–1,350°C (H₂/N₂ atmosphere) |
| Best For | Medical devices, marine hardware, chemical equipment, surgical instruments | Food processing, architectural hardware, consumer products |
| Cost Index (relative) | $$ (moderate) | $ (economy) |
When to choose 316L over 304: If your part will face chloride exposure (salt water, body fluids, chemical washdown), the 2-3% molybdenum in 316L provides critical pitting resistance that 304 lacks. For medical implants and surgical tools, 316L is the standard.
Martensitic Stainless Steels: 17-4PH and 420
| Property | MIM 17-4PH (H900) | MIM 420 (Hardened) |
|---|---|---|
| Density (sintered) | 7.70 g/cm³ (≥96%) | 7.65 g/cm³ (≥95%) |
| Yield Strength | 1,170–1,310 MPa | 1,000–1,350 MPa |
| UTS | 1,310–1,450 MPa | 1,400–1,800 MPa |
| Elongation | 8–14% | 2–8% |
| Hardness | 40–47 HRC | 48–56 HRC |
| Corrosion Resistance | Good (comparable to 304) | Moderate (hardenable, not for chloride exposure) |
| Magnetic? | Magnetic | Magnetic |
| Heat Treatment | Solution anneal + age harden (H900: 480°C, 1 hr) | Quench from 980–1,050°C + temper |
| Best For | Firearms components, aerospace brackets, high-strength fasteners, valve parts | Cutlery, wear parts, medical cutting instruments, valve seats |
| Cost Index | $$$ (premium) | $$ (moderate) |
17-4PH vs 420 decision rule: Choose 17-4PH when you need high strength with good corrosion resistance (aerospace, firearms, marine). Choose 420 when wear resistance and edge retention matter more than corrosion resistance (cutting tools, wear plates).
Low-Alloy Steel MIM Materials
Low-alloy steels offer the best strength-to-cost ratio in MIM. They require heat treatment (quench and temper) after sintering and typically need a protective coating (plating, black oxide, or oil) for corrosion resistance.
4605, 8620, and 4340
| Property | MIM 4605 (Q&T) | MIM 8620 (Q&T) | MIM 4340 (Q&T) |
|---|---|---|---|
| Density | 7.55 g/cm³ (≥95%) | 7.55 g/cm³ (≥95%) | 7.55 g/cm³ (≥95%) |
| Yield Strength | 1,100–1,380 MPa | 750–950 MPa | 1,200–1,480 MPa |
| UTS | 1,380–1,650 MPa | 900–1,100 MPa | 1,450–1,750 MPa |
| Elongation | 2–5% | 8–15% | 5–10% |
| Hardness | 35–45 HRC | 25–35 HRC | 38–48 HRC |
| Wear Resistance | Good (tempered martensite) | Moderate (case-hardenable) | Very good (high hardenability) |
| Key Feature | Highest strength for cost | Best toughness + case-hardenability | Deep hardening + fatigue resistance |
| Best For | Firearms hammers/sears, automotive gears, power tool components | Gears, shafts, cam lobes, transmission parts that require case hardening | Aircraft landing gear parts, high-stress fasteners, structural components |
| Cost Index | $ (most economical) | $ (most economical) | $$ (moderate) |
4605 is the workhorse. For most non-corrosion applications requiring high strength at low cost, 4605 MIM is the default choice. It delivers 1,100+ MPa yield strength after quench and temper — comparable to heat-treated wrought alloy steels — at a fraction of the machining cost.
Tool Steel MIM Materials
| Property | MIM M2 Tool Steel | MIM 440C (Hardened) |
|---|---|---|
| Density | 7.90 g/cm³ (≥97%) | 7.60 g/cm³ (≥96%) |
| Hardness | 60–65 HRC | 58–60 HRC |
| Wear Resistance | Excellent (high-speed steel) | Very good (high-carbon martensitic) |
| Best For | Cutting tools, dies, punches, wear inserts | Bearings, valve components, pump parts |
| Cost Index | $$$ (premium) | $$$ (premium) |
Titanium MIM Materials
| Property | MIM Ti-6Al-4V (Annealed) | MIM CP Titanium (Grade 2) |
|---|---|---|
| Density | 4.43 g/cm³ (≥96%) | 4.51 g/cm³ (≥96%) |
| Yield Strength | 830–900 MPa | 275–345 MPa |
| UTS | 900–950 MPa | 345–415 MPa |
| Elongation | 8–12% | 20–25% |
| Biocompatibility | Excellent (ISO 5832-3) | Excellent (ISO 5832-2) |
| Density Advantage | 45% lighter than steel | 45% lighter than steel |
| Best For | Aerospace structural parts, medical implants, high-performance sporting goods | Chemical processing, marine hardware, medical devices requiring maximum formability |
| Cost Index | $$$$ (highest) | $$$$ (highest) |
Titanium MIM trade-off: Ti-6Al-4V MIM delivers wrought-comparable mechanical properties at 45% less weight than steel — but at 5-10× the raw material cost and with a more demanding sintering process (vacuum or high-purity argon, 1,250-1,350°C). Reserve titanium MIM for applications where weight reduction or biocompatibility is non-negotiable.
Specialty Alloys for MIM
| Alloy Family | Key Properties | Typical Applications | Sintering Notes |
|---|---|---|---|
| Kovar (ASTM F15) Fe-29Ni-17Co | CTE 4.5–5.5 × 10⁻⁶/°C (matches glass/ceramic) | Hermetic connectors, microwave tubes, glass-to-metal seals | 1,300–1,350°C in H₂ |
| Cobalt-Chrome (ASTM F75) | YS 450–650 MPa, UTS 650–880 MPa, elongation 8–20% | Orthopedic implants, dental prosthetics | 1,300–1,350°C in vacuum |
| Soft Magnetic Alloys Fe-50Ni, Fe-4Ni, Fe-0.45P | High permeability, low coercivity (< 80 A/m for Fe-50Ni) | Solenoid cores, sensors, relay armatures, magnetic shields | 1,250–1,350°C in H₂ |
| Copper Alloys | Thermal conductivity 250–390 W/m·K; electrical 60–90% IACS | Heat sinks, electrical contacts, thermal management | Controlled atmosphere to prevent oxidation |
| Tungsten Heavy Alloys W-Ni-Fe / W-Ni-Cu | Density 17.0–18.5 g/cm³ (90–97% W) | Radiation shielding, counterweights, kinetic penetrators | 1,450–1,500°C in H₂ |
MIM Material Selection by Industry
| Industry | Typical Requirements | Primary Recommendation | Alternative |
|---|---|---|---|
| Medical devices | Biocompatibility, sterilization, corrosion resistance | 316L / Ti-6Al-4V | 17-4PH / ASTM F75 |
| Automotive | High strength, wear resistance, cost control | 4605 (Q&T) | 8620 / 17-4PH |
| Firearms | High hardness, impact resistance, magnetic | 17-4PH (H900) | 4605 / 420 |
| Consumer electronics | Miniaturization, cosmetic finish, wear resistance | 316L / 17-4PH | 4605 + plating |
| Aerospace | Strength-to-weight, fatigue resistance | Ti-6Al-4V / 17-4PH | 4340 |
| Electronics packaging | CTE matching, hermeticity | Kovar (ASTM F15) | Invar (Fe-36Ni) |
| Magnetic actuators | High permeability, low coercivity | Fe-50Ni | Fe-4Ni |
| Radiation / defense | Maximum density | W-Ni-Fe | W-Ni-Cu (non-magnetic) |
Quick Material Decision Matrix
| Requirement | Recommended Material | Alternative |
|---|---|---|
| Maximum corrosion resistance | MIM 316L | PANACEA (Ni-free) |
| Highest strength & corrosion | MIM 17-4PH (H900) | MIM 420 (lower corrosion) |
| Best strength-to-cost ratio | MIM 4605 (Q&T) | MIM 8620 (for case hardening) |
| Maximum wear resistance | MIM M2 Tool Steel | MIM 440C |
| Lightest weight | MIM Ti-6Al-4V | MIM Aluminum (emerging) |
| Glass-to-metal sealing | Kovar (ASTM F15) | Invar (Fe-36Ni) for lower cost |
| Medical implant (load-bearing) | MIM Ti-6Al-4V | Cobalt-Chrome (ASTM F75) |
| Magnetic actuator core | Fe-50Ni (soft magnetic) | Fe-4Ni (cost-sensitive) |
| Maximum density (radiation shielding) | W-Ni-Fe (17-18.5 g/cm³) | W-Ni-Cu (non-magnetic) |
| Best surface finish (as-sintered) | MIM 316L or 17-4PH | MIM Low-Alloy (requires coating) |
How to Request a Material Recommendation
Every MIM part is different. The optimal material depends on:
- Mechanical requirements: Yield strength, hardness, elongation, fatigue life
- Environment: Temperature range, chemical exposure, UV/outdoor, body fluid contact
- Magnetic behavior: Non-magnetic, soft magnetic, or hard magnetic
- Surface finish: As-sintered, polished, plated, coated, or passivated
- Regulatory: ISO 5832 (medical), ASTM, AMS, RoHS, REACH
- Budget: Material cost, tooling amortization, post-processing
Get Your Free Material Recommendation
Send your 2D/3D drawing (STEP, IGES, PDF) with your target application. Our metallurgists will respond within 24 hours with:
- Recommended MIM material grade with rationale
- Estimated mechanical properties (sintered + heat treated)
- DFM feedback on geometry, wall thickness, and tolerances
- Budgetary tooling and production cost estimate
Frequently Asked Questions
Q: Q1: Which MIM material has the best strength-to-cost ratio?
MIM 4605 low-alloy steel offers the best strength per dollar. After quench and temper (oil quench from 850°C, temper at 200-350°C), it reaches 1,100-1,380 MPa yield strength with only moderate material cost. The main trade-off is that it requires corrosion protection (plating or coating) and has lower ductility (2-5% elongation) compared to stainless grades.
Q: Q2: Can MIM 17-4PH match wrought 17-4PH properties?
Yes. Sintered MIM 17-4PH at ≥96% density, when solution treated (1,040°C, 30 min) and aged to H900 condition (480°C, 1 hr), achieves yield strength of 1,170-1,310 MPa — within 5% of wrought 17-4PH H900 values. Fatigue strength is approximately 85-90% of wrought due to residual micro-porosity, which should be factored into designs for cyclic loading.
Q: Q3: Is 316L or 304 better for MIM medical parts?
316L is strongly preferred for medical MIM parts. Its 2-3% molybdenum content provides critical resistance to pitting corrosion from chlorides (body fluids, saline, sterilization chemicals). 316L also meets ASTM F138 and ISO 5832-1 standards for surgical implants, which 304 does not.
Q: Q4: How do I choose between 4605, 8620, and 4340?
4605 for maximum strength and hardness on a budget. 8620 when you need case hardening (hard, wear-resistant surface with a tough core) — typical for gears and shafts. 4340 when you need deep hardening plus high fatigue resistance — typical for aircraft structural parts and high-stress fasteners.
Q: Q5: Can you MIM tungsten alloys?
Yes. W-Ni-Fe and W-Ni-Cu alloys with 90-97% tungsten content are successfully MIM-processed at Emitech. Sintering occurs at 1,450-1,500°C in hydrogen atmosphere, achieving 97-99% theoretical density (17.0-18.5 g/cm³). These are used for radiation shielding collimators, counterweights, and defense applications where machining is cost-prohibitive.
References & Standards
- MPIF Standard 35, Materials Standards for Metal Injection Molded Parts, 2020 Edition.
- ASTM A240/A240M, ASTM A276/A276M, ASTM F138, ASTM F75 — relevant material specifications.
- ISO 5832-1:2024, Implants for surgery — Metallic materials — Part 1: Wrought stainless steel.
- German, R.M., Metal Injection Molding: A Comprehensive MIM Design Guide, MPIF, 2019.
Source Custom MIM Parts from Emitech
Nanjing Emitech delivers MIM from tooling through sintering and finishing, plus precision CNC machining for prototypes and secondary operations. Custom MIM parts · CNC machining services · MIM services · Request a quote