Advanced Powder Products, Inc.
301 Enterprise Drive
Philipsburg, PA 16866
(814) 342-5898
Stainless steel is one of the most widely used materials in metal injection molding (MIM), offering an optimal balance of mechanical properties, corrosion resistance, and design flexibility.
At Advanced Powder Products (APP), we specialize in MIM grade stainless to produce complex parts at high volumes while maintaining exceptional performance and visual appeal. This guide explores the advantages of stainless steel MIM, compares it to alternative materials, and highlights its ideal applications.
This corrosion resistant steel combines the inherent benefits of stainless with the efficiency of the MIM process, resulting in precision parts with outstanding performance characteristics.
One of the most significant advantages of this material is its excellent corrosion resistance. High chromium content in MIM alloy forms a passive oxide layer on the surface, shielding parts from moisture, chemicals, and harsh environments. This makes it ideal for medical devices, consumer products, and components exposed to humid or corrosive settings.
The stainless formulation delivers a strong combination of tensile strength, hardness, and wear resistance. The sintered parts maintain close dimensional tolerances, ensuring consistent performance for structural and functional applications.
The MIM process allows for the efficient manufacture of high volumes of small, intricate parts with repeatable results. This formulaton is particularly well-suited for industries requiring consistent part quality and scalable production, including aerospace, automotive, and medical device sectors.
MIM stainless enables the design and production of complex geometries that would be cost-prohibitive or impossible with traditional machining. This includes features like undercuts, threads, and thin walls, supporting innovation in part design.
The alloy provides a naturally clean and professional finish, which is often desirable in consumer-facing or high-precision applications. Post-processing such as polishing, passivation, or coating can further enhance the part’s visual appeal and functionality.
See chart below for typical MIM stainless steel grades and mechanical properties.
| Microstructure | Grade | Alloy Features | Applications |
|---|---|---|---|
| Precipitation Hardening | 17-4PH | Strength, Heat Treatable, Corrosion Resistance | Firearms, Medical Devices (mechanical joints, suturing saws, wound forceps), Hand & Power Tools, Sporting Goods, Electronics, Aerospace, Automotive, Fiber Optic Connectors, and Consumer Goods. |
| Austenitic | 316L | Superior Corrosion Resistance, Ductility, Non-magnetic | |
| Martensitic | 420, 440C | Hardness, Wear Resistance, Heat Treatable | |
| Ferritic | 430L | Magnetic Stainless Steel with Resistance to Atmospheric Corrosion and General Oxidation |
| Precipitation Hardening |
| Grade |
| 17-4PH |
| Alloy Features |
| Strength, Heat Treatable, Corrosion Resistance |
| Applications |
| Firearms, Medical Devices (mechanical joints, suturing saws, wound forceps), Hand & Power Tools, Sporting Goods, Electronics, Aerospace, Automotive, Fiber Optic Connectors, and Consumer Goods. |
| Austenitic |
| Grade |
| 316L |
| Alloy Features |
| Superior Corrosion Resistance, Ductility, Non-magnetic |
| Applications |
| Firearms, Medical Devices (mechanical joints, suturing saws, wound forceps), Hand & Power Tools, Sporting Goods, Electronics, Aerospace, Automotive, Fiber Optic Connectors, and Consumer Goods. |
| Martensitic |
| Grade |
| 420, 440C |
| Alloy Features |
| Hardness, Wear Resistance, Heat Treatable |
| Applications |
| Firearms, Medical Devices (mechanical joints, suturing saws, wound forceps), Hand & Power Tools, Sporting Goods, Electronics, Aerospace, Automotive, Fiber Optic Connectors, and Consumer Goods. |
| Ferritic |
| Grade |
| 430L |
| Alloy Features |
| Magnetic Stainless Steel with Resistance to Atmospheric Corrosion and General Oxidation |
| Applications |
| Firearms, Medical Devices (mechanical joints, suturing saws, wound forceps), Hand & Power Tools, Sporting Goods, Electronics, Aerospace, Automotive, Fiber Optic Connectors, and Consumer Goods. |
| Element | MIM 17-4PH SS | MIM 316L | MIM 420 | MIM 440 | MIM 430L |
|---|---|---|---|---|---|
| C | 0.07 max | .03 max | .15-.4 | .9-1.25 | .05 (max) |
| Si | 1.0 max | 1.0 max | 1.0 max | 1.0 max | 1.0 max |
| Cr | 15.5-17.5 | 16-18 | 12-14 | 16-18 | 16-18 |
| Mo | - | 2-3 | - | .75 max | - |
| Mn | 1.0 max | 2.0 max | 1.0 max | 1.0 max | 1.0 max |
| Fe | Bal. | Bal. | Bal. | Bal. | Bal. |
| Ni | 3-5 | 10-14 | - | .6 max | - |
| Cu | 3-5 | - | - | - | - |
| Nb | 0.15-0.45 | - | - | - | - |
| Carbon (C) | |
| MIM 17-4PH SS | MIM 316L |
| 0.07 max | .03 max |
| MIM 420 | MIM 440 |
| .15 - .4 | .9 - 1.25 |
| MIM 430L | |
| .05 max | |
| Silicon (Si) | |
| MIM 17-4PH SS | MIM 316L |
| 1.0 max | 1.0 max |
| MIM 420 | MIM 440 |
| 1.0 max | 1.0 max |
| MIM 430L | |
| 1.0 max | |
| Chromium (Cr) | |
| MIM 17-4PH SS | MIM 316L |
| 15.5 - 17.5 | 16 - 18 |
| MIM 420 | MIM 440 |
| 12 - 14 | 16 - 18 |
| MIM 430L | |
| 16 - 18 | |
| Molybdenum (Mo) | |
| MIM 17-4PH SS | MIM 316L |
| - | 2 - 3 |
| MIM 420 | MIM 440 |
| - | .75 max |
| MIM 430L | |
| - | |
| Manganese (Mn) | |
| MIM 17-4PH SS | MIM 316L |
| 1.0 max | 2.0 max |
| MIM 420 | MIM 440 |
| 1.0 max | 1.0 max |
| MIM 430L | |
| 1.0 max | |
| Iron (Fe) | |
| MIM 17-4PH SS | MIM 316L |
| Bal. | Bal. |
| MIM 420 | MIM 440 |
| Bal. | Bal. |
| MIM 430L | |
| Bal. | |
| Nickel (Ni) | |
| MIM 17-4PH SS | MIM 316L |
| 3 - 5 | 10 - 14 |
| MIM 420 | MIM 440 |
| - | .6 max |
| MIM 430L | |
| - | |
| Copper (Cu) | |
| MIM 17-4PH SS | MIM 316L |
| 3 - 5 | - |
| MIM 420 | MIM 440 |
| - | - |
| MIM 430L | |
| - | |
| Niobium (Nb) | |
| MIM 17-4PH SS | MIM 316L |
| 0.15 - 0.45 | - |
| MIM 420 | MIM 440 |
| - | - |
| MIM 430L | |
| - | |
| Material | Density (g/cm3) | YS (MPa) | UTS (MPa) | Elongation (%) | Unnotched Charpy impact energy (J) | Macro Hardness | Young's Modulus (GPa) |
|---|---|---|---|---|---|---|---|
| MIM 17-4 PH | 7.6 | 740 | 900 | 6 | 100 | 27-32 HRC | 190 |
| MIM 17-4 PH (H900) | 7.6 | 1100 | 1200 | 4 | 100 | 38-42 HRC | 190 |
| MIM 316L | 7.6 | 180 | 520 | 40 | 140 | 67 HRB | 190 |
| MIM 420 (heat treated) | 7.4 | 1200 | 1370 | - | 30 | 44 HRB | 190 |
| MIM 440 (heat treated) | 7.5 | 1600 | 1250 | 1 | 4 | 55 HRC | 190 |
| MIM 430L | 7.5 | 230 | 410 | 25 | 110 | 65 HRB | 190 |
| MIM 17-4 PH | |
| Density (g/cm3) | YS (MPa) |
| 7.6 | 740 |
| UTS (MPa) | Elongation (%) |
| 900 | 6 |
| Macro Hardness | Young's Modulus (GPa) |
| 27 - 32 HRC | 190 |
| Unnotched Charpy Impact Energy (J) | |
| 100 | |
| MIM 17-4 PH (H900) | |
| Density (g/cm3) | YS (MPa) |
| 7.6 | 1100 |
| UTS (MPa) | Elongation (%) |
| 1200 | 4 |
| Macro Hardness | Young's Modulus (GPa) |
| 27 - 32 HRC | 190 |
| Unnotched Charpy Impact Energy (J) | |
| 100 | |
| MIM 316L | |
| Density (g/cm3) | YS (MPa) |
| 7.6 | 180 |
| UTS (MPa) | Elongation (%) |
| 520 | 40 |
| Macro Hardness | Young's Modulus (GPa) |
| 67 HRB | 190 |
| Unnotched Charpy Impact Energy (J) | |
| 140 | |
| MIM 420 (heat treated) | |
| Density (g/cm3) | YS (MPa) |
| 7.4 | 1200 |
| UTS (MPa) | Elongation (%) |
| 1370 | - |
| Macro Hardness | Young's Modulus (GPa) |
| 44 HRB | 190 |
| Unnotched Charpy Impact Energy (J) | |
| 30 | |
| MIM 440 (heat treated) | |
| Density (g/cm3) | YS (MPa) |
| 7.5 | 1600 |
| UTS (MPa) | Elongation (%) |
| 1250 | 1 |
| Macro Hardness | Young's Modulus (GPa) |
| 55 HRC | 190 |
| Unnotched Charpy Impact Energy (J) | |
| 4 | |
| MIM 430L | |
| Density (g/cm3) | YS (MPa) |
| 7.5 | 230 |
| UTS (MPa) | Elongation (%) |
| 410 | 25 |
| Macro Hardness | Young's Modulus (GPa) |
| 65 HRB | 190 |
| Unnotched Charpy Impact Energy (J) | |
| 110 | |
Choosing the right material for your molded parts depends on performance requirements, environment, and cost constraints. Here’s how stainless steel MIM compares to common alternatives:
Low alloy steels offer higher strength and hardness when heat-treated, but they generally fall short on corrosion resistance. If your application involves exposure to moisture or chemicals, corrosion-resistant MIM steel is often a better fit.
Tool steels are engineered for maximum hardness and wear resistance. However, they typically lack corrosion resistance. Stainless alloy MIM provides a balanced solution for parts needing both strength and resistance to rust or oxidation.
MIM 316L stainless variant is frequently used in medical devices due to its biocompatibility and corrosion resistance. For critical implants, materials like titanium may be preferred, but stainless steel remains a viable and cost-effective option for many non-implantable components.
While plastic injection molding offers design flexibility and low part cost, it cannot match the mechanical properties or temperature tolerance of MIM stainless. For load-bearing, wear-resistant, or high-heat applications, metal particles in MIM parts provide a superior alternative.
In the MIM process, stainless steel parts begin as "green parts"—a mixture of metal powder and binder. These are molded into shape before undergoing debinding and sintering. This approach enables cost-efficient, near-net-shape production without sacrificing part performance.
See chart below for a comparative summary of stainless steel vs. alternative MIM materials.
