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PRODUCT DATA of AISI 440A
MaterialAISI 440A
General InformationThis is a high carbon martensitic stainless with moderate corrosion resistance good strength and the ability to obtain and keep excellent hardness (Rc 56) and wear resistance.
Use in SpacecraftBall bearings and races, gage blocks, molds and dies, valve components
Chemical Composition0.6-0.75C, 16-18Cr, rem Fe
EXPERIENCE IN PRACTICE
Development StatusCommercial Product
Cost RangeLow
PHYSICAL PROPERTIES
Crystal StructureFace centered cubic (fcc)
Magnetic PropertiesFerromagnetic
ELECTRICAL PROPERTIES
Electrical Volume Resistivity6e-7 ohm.m
THERMAL PROPERTIES
Thermal Conductivity24.2 W/m.K
Thermal Expansion Coefficient10.2 ustrain/C
Specific Heat0.46 J/g.K
RELEVANT PROPERTIES FOR USE IN SPACE COMMUNITY
General Corrosion StatusRequires specific corrosion protection
Atmospheric CorrosionThis alloy is not really stainless. Should be covered with oil or grease at all times.
Stress Corrosion StatusLow Resistance to SCC: Table 3
Data Quality: Design Data
Bimetallic CorrosionCan 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
Machinabilityest machined in the annealed condition. Tough, stringy chips can be best handled by the use of chip breakers. Carbide or ceramic tooling is recommended.
WeldingThis alloy is not commonly welded due to its tendency to air harden.