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| PRODUCT DATA of AISI 440C |
| Material | AISI 440C |
| Product Datasheet | 440C |
| General Information | This is a high carbon martensitic stainless steel with moderate corrosion resistance good strength and the ability to obtain and keep excellent hardness (Rc 60) and wear
resistance. Ball bearings and races.
Data for hardened and stress relieved |
| Precautions | Cracking may occur on heating, cooling, pickling or after welding. This steel is particularly subject to decarburization because of their high carbon content. Use of protective, non-decarburizing atmospheres in heat treatments is recommended. This steel is subject to severe embrittlement by gaseous hydrogen |
| Chemical Composition | Fe-17Cr-0.75Mo-1.2C |
| EXPERIENCE IN PRACTICE |
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| Development Status | Commercial Product |
| Cost Range | Low |
| Equivalent Designations | 1.4125; X105CrMo17; Z100CD17 |
| Space Experience | Good |
| PHYSICAL PROPERTIES |
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| Crystal Structure | Face centered cubic (fcc) |
| Specific Gravity | 7.75 |
| Magnetic Properties | Ferromagnetic |
| ELECTRICAL PROPERTIES |
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| Electrical Volume Resistivity | 6e-7 ohm.m |
| THERMAL PROPERTIES |
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| Thermal Expansion Coefficient | 10.2 μstrain/°C |
| Melting Range | 1370 to 1480 °C |
| Specific Heat | 0.46 J/g.K |
| RELEVANT PROPERTIES FOR USE IN SPACE COMMUNITY |
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| General Corrosion Status | Requires specific corrosion protection |
| Atmospheric Corrosion | This alloy is not really stainless. Should be covered with oil or grease at all times |
| Stress Corrosion Status | Low Resistance to SCC: Table 3 Data Quality: Design Data |
| EMF vs SCE | -0.2 V Remark: Measured in 3.5% NaCl solution. Passive condition Data Quality: Design Data |
| Bimetallic Corrosion | Can be connected without any restriction to: Cr, Au, Ag, Gun-metal, P-bronzes, Sn-bronzes, Ti+alloys, Ni, Monel, Inconel, Ni/Mo alloys
Can be connected in a non-controlled environment to the above and Cd, austenitic cast iron, Cu, Brasses, Al-bronzes, Si-bronzes, Au, Pt, C, Rh, Sn-Pb alloys, Sn, Pb, 300 series stainless steels Can be connected in a clean room environment to above and Al-Cu alloys Needs specific measures: All others Test:ECSS-Q-ST-70C Rev.1 Table 5.1 Data Quality: Design Data |
| Machinability | This alloy is difficult to machine. Machining is generally performed in the fully annealed condition for bar and forgings, and in the spheroidized condition for castings. The use of carbide or ceramic tools is recommended. Machinability rating of these alloys is about 40 percent of that of mild steel. |
| Welding | This alloy is not commonly welded due to its tendency to air harden. |
| FLUID SYSTEMS COMPATIBILITY |
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| Low Pressure Hydrogen (LOH2) | Fails mechanical impact |
| High Pressure Hydrogen (HIH2) | Fails mechanical impact |
| SPECIAL RECOMMENDATIONS |
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| Special Recommendations | Cracking may occur on heating, cooling, pickling or after welding. These steels are particularly subject to decarburization because of their high carbon content. Use of protective, on-decarburizing atmospheres in heat treatments is recommended. |