Stainless Steel 420 (AMS 5620/AMS 5621)

Technical Data Sheet


Chemical Composition Limits
Weight% C P Si Fe Mn S Cr
Alloy 420 0.15 min 0.040 max 1.00 max Bal 1.00 max 0.030 max 12-14

Alloy 420 is a martensitic stainless steel of the 12% Chromium type. Due to it's Chromium content 420 will achieve high hardness. Alloy 420 is used in many different applications including surgical and dental instruments, scissors, needle valves, gears, ball bearings, magnets etc. Alloy 420 should not be used for springs or heavily stressed parts that require to be operated at sub-zero temperatures. 

Typical Mechanical Properties


Material Tensile Strength (Mpa) Proof Stress 0.2% (MPa) % Elongation in 2" % Reduction of Area Hardness Brinell
Alloy 420 Ann
Room Temp 1" Round Bar
655 345 25 55 196

Alloy 420 is available in Bar (Hexagon, Round, Square, Flat), Billet, Wire, Strip. For all stock availability contact Sales.

AMS 5506 Sheet / strip / plate
AMS 5620 Bars / forging (free mach)
AMS 5621 Bars / wire / forgings
ASTM A276 / ASME SA276
ASTM A314 / ASME SA314
ASTM A484 / ASME SA484
ASTM A580 / ASME SA580
BS 3S62
BS 970; 420S37 / 420S29 / 420S45
EN56B / EN56C / EN56D
WS 1.3541
WS 1.4024
WS 1.4028
UNS S42000

At Aircraft Materials all stock items can be shipped out within 24 hours, usually within the same day. Even cutting orders for bar or sheet can be processed and dispatched the same day, and for time-critical situations such as AOGs, we have a dedicated AOG service desk ready to help (

Thanks to our global logistics network we can source from anywhere in the world in just a few days. We use a range of transport partners to enable us to ship overnight within the U.K. and Europe and provide fast shipping solutions to the rest of the world. If your requirement is urgent we can offer a priority shipping service, but also if time is not so critical we can offer more cost-effective options to ensure you get the best value for money. To find out more about our services click here.

Every effort is made to ensure that technical specifications are accurate. However, technical specifications included herein should be used as a guideline only. All specifications are subject to change without notice.

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