| Analysis | Mechanical_Properties | Applications | Machineability_and_Weldability | Heat_Treating | Tolerances | Speedy Metals items |
420 stainless steel is a martensitic higher carbon version of types 410 and 416 stainless that can be hardened by heat treatment. It contains a minimum of 12 percent chromium, sufficient to give 420 corrosion resistance properties. It has good ductility in the annealed condition but is capable of being hardened up to 50 RHC. Its best corrosion resistance is achieved when 420 is hardened and surface ground or polished. In the hardened condition, 420 has good corrosion resistance to the atmosphere, foods, fresh water, mild alkalies and acids, steam, sterilizing solutions, crude oil, gasoline, and other similar corrosive media. The higher carbon content employed in 420 gives higher strength and hardness over stainless grades 410 and 416. In the annealed condition, 420 is relatively easy to machine, but if hardened to above 30 HRC, machining becomes more difficult. Fabrication must be by methods allowing for poor weldability and usually allow for a final harden and temper heat treatment. 420 is not recommended for use in temperatures above the relevant tempering temperature, because of reduction in mechanical properties. The scaling temperature is approximately 650°F.
420 stainless generally conforms to ASTM A276, ASTM A314, AMS 5506, AMS A314, QQ-S-763
The above values are average and may be considered as representative of 420 stainless (annealed)
420 Stainless is commonly used for dental and surgical instruments, pump shafts, plastic molds and dies, steel balls, various hand tools, lens molds, scissors, straight edges, cutlery, gauges, needle valves, ball check valves, gear shafts, cams, pivots, ball bearings, etc
Machinability is rated at 30% of B1112. Similar to machining high-carbon, high-chromium tools steels, but 420 creates tough, stringy chip buildup.
420 stainless is not commonly welded due to its air hardening characteristics. Welding may be performed after preheating to 300°-400°F with post weld tempering at temperature for 2 hours.
420 can be hot worked by slowly bring temperature to 1400° F, then on to 2000°-2200°F.Reheat often to keep the temperature above 1600°F. After working, cool in furnace slowly to avoid cracking. 420 will withstand only minor cold working. Radical forming operations will result in cracking.
Hardening range is between 1850° and 1950° F. Quench in heated oil. Temper to required hardness.
TEMPERING
Tempering range is 300°-400°F. Air cool for maximum hardness and corrosion resistance.
ANNEALING
Full annealing range is between 1550° and 1650° F. Cool slowly in furnace.
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ROUND (drawn, smooth turned, or ground) |
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|
size (inches) |
OVER |
UNDER |
|
.044 to 5/16, incl |
0.001 |
0.001 |
|
5/16 to 1/2, excl |
0.0015 |
0.0015 |
|
1/2 to 1, excl |
0.002 |
0.002 |
|
1 to 1-1/2, excl |
0.0025 |
0.0025 |
|
1-1/2 to 4, incl |
0.003 |
0.003 |
|
4-1/8 to 4-1/2, incl |
0.005 |
0.005 |
|
4-9/16 to 6, incl |
0.008 |
0.008 |