{"id":3641,"date":"2026-09-16T11:12:58","date_gmt":"2026-09-16T08:12:58","guid":{"rendered":"https:\/\/www.defencemetal.com\/index.php\/en\/aisi-420c\/"},"modified":"2026-09-25T21:15:17","modified_gmt":"2026-09-25T18:15:17","slug":"aisi-420c","status":"publish","type":"page","link":"https:\/\/www.defencemetal.com\/index.php\/en\/aisi-420c\/","title":{"rendered":"AISI 420C \/ (1.4034)"},"content":{"rendered":"

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AISI 420C \/ (1.4034) \/ UNS S42000 \/ AMS 5506 \/ AMS 5620<\/h1>\n
DEFENCE METAL<\/span><\/p>\n
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AISI 420C<\/div>\n
UNS S42000 \u00b7 W.Nr. 1.4034 \u00b7 X46Cr13 \u00b7 designated 420C in ASTM F899 \u00b7 a MARTENSITIC stainless steel. THE CARBON BAND IS 0.43-0.50%, the HIGHEST of the four grades. Cr 12.5-14.5% – the chromium band is also HIGHER than in the other three (11.5-13.5% and 12.0-14.0% on the 410 and 420 side). Si 1.00% max \u00b7 Mn 1.00% max \u00b7 P 0.040% max \u00b7 balance Fe. The sulfur ceiling varies with the source: 0.015% max in Lucefin and Notz, 0.030% max in Swiss Steel, Rodacciai and AGST. THERE IS A SPECIFICATION DIFFERENCE AT THE CARBON FLOOR: the EN 10088-2 and EN 10088-3 floor is 0.43%, while the 420C floor in ASTM F899 is 0.42%. ‘420C’ IS NOT AN ASTM A276 GRADE NAME: A276 carries only a ‘Type 420’ row. It does NOT precipitation harden; it hardens by quenching and tempering.<\/p>\n
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Not to be confused with<\/div>\n

AISI 420B<\/a><\/div>\n<\/div>\n<\/div>\n

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For what<\/div>\n
Bought for parts where hardness and wear resistance come before everything else and corrosion resistance is secondary: blades and cutting edges, scissors, surgical and dental instruments, bearing balls and races, plastic injection moulds, journals, shafts, measuring and gauge parts, spring and lock\u2026<\/div>\n<\/div>\n
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Forms<\/div>\n
Round bar, flat bar, plate, sheet, pipe, forging. All forms are supplied to order.<\/div>\n<\/div>\n
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Standards<\/div>\n
EN: 1.4034 \u00b7 10088-2 (flat products; ONLY the annealed +A condition is listed) \u00b7 10088-3 (bars) \u00b7 10250-4 (open die forgings) \u00b7 EN ISO 7153-1:2016 (surgical instruments, 1.4034 \/ X46Cr13). ASTM: F899 (surgical instruments; 420C = C 0.42-0.50%, Cr 12.50-14.50%, Ni 1.00% max, UNS S42000) \u00b7 A276 \/ SA-276 (bars and shapes; carried in the standard as ‘Type 420’, Condition A only, with a hardness ceiling) \u00b7 A484 \/ SA-484 (general requirements) \u00b7 A580 \/ SA-580 (wire) \u00b7 A314 \/ SA-314 (billets and bars for forging). Welding wire: AWS A5.9 \/ SFA-5.9 ER420. AMS: there is NO AMS number covering 1.4034 – see the specification note.
THERE IS NO AMS – THIS IS THE MOST IMPORTANT NOTE ON THIS CARD. Verified from SAE title records: all three AMS numbers that circulate under the 420 name sit in the ’13Cr (0.30 – 0.40C)’ band: AMS 5506 (sheet, strip, plate), AMS 5621 (bars, wire, forgings) and\u2026<\/span><\/div>\n<\/div>\n
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Advantage<\/div>\n
It delivers the HIGHEST ATTAINABLE HARDNESS of the four grades, and the numbers for that sit in one Notz document: 44-50 HRC for 1.4021, 45-51 HRC for 1.4028, 52-55 HRC for 1.4034. Same document, same cycle, carbon the only variable.<\/div>\n<\/div>\n
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Welding<\/div>\n
420C IS NOT A SUITABLE MATERIAL FOR WELDING and is not normally welded. At 0.43-0.50% carbon the heat affected zone turns to very hard, brittle martensite and cracks under shrinkage stress and hydrogen.<\/div>\n<\/div>\n
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Limits<\/div>\n
1) FORBIDDEN TEMPERING BAND: 425-600 \u00b0C. Abrams states it directly for 1.4034: for the best corrosion resistance and mechanical properties the 425-600 \u00b0C range must be avoided, and in the 427-593 \u00b0C range impact toughness falls through temper embrittlement.<\/div>\n<\/div>\n
REQUEST A QUOTE<\/a>All stainless steels →<\/a>TECHNICAL DETAILS ↓<\/span><\/div>\n
Compiled from manufacturer data sheets \u00b7 confirm against the current specification before ordering<\/div>\n<\/div>\n<\/div>\n

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