{"id":3549,"date":"2026-09-16T10:58:58","date_gmt":"2026-09-16T07:58:58","guid":{"rendered":"https:\/\/www.defencemetal.com\/index.php\/en\/aisi-8620\/"},"modified":"2026-09-25T16:31:06","modified_gmt":"2026-09-25T13:31:06","slug":"aisi-8620","status":"publish","type":"page","link":"https:\/\/www.defencemetal.com\/index.php\/en\/aisi-8620\/","title":{"rendered":"AISI 8620 \/ AMS 6274"},"content":{"rendered":"

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AISI 8620 \/ (1.6523) \/ UNS G86200 \/ AMS 6274<\/h1>\n
DEFENCE METAL<\/span><\/p>\n
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AISI 8620<\/div>\n
UNS G86200 (hardenability-band grade 8620H = H86200) \u00b7 W.Nr. 1.6523 \u00b7 EN 10084 name 20NiCrMo2-2 (FORMER DIN NAME 21NiCrMo2; resulphurised free-machining variant 20NiCrMoS2-2 = 1.6526) \u00b7 SAE J404 \/ ASTM A29 band: C 0.18-0.23% – Mn 0.70-0.90% – Si 0.15-0.35% – Ni 0.40-0.70% – Cr 0.40-0.60% – Mo 0.15-0.25% – P 0.035% max – S 0.040% max – balance Fe. The nominal form used in the AMS titles is 0.50Cr – 0.55Ni – 0.20Mo (0.18-0.23C). THE EN 10084 20NiCrMo2-2 BAND IS NOT THE SAME: C 0.17-0.23% – Si 0.40% max – Mn 0.65-0.95% – Cr 0.35-0.70% – Mo 0.15-0.25% – Ni 0.40-0.70% – P 0.025% max – S 0.020-0.040%. The EN band is WIDER on chromium and manganese, and EN also sets a LOWER limit on sulphur (0.020%) where SAE sets none. Material delivered against a 20NiCrMo2-2 certificate therefore does not automatically satisfy an 8620 order; acceptance depends on the heat analysis meeting both bands. IT IS A CARBURIZING (CASE-HARDENING) STEEL: its carbon is low and it does not harden usefully by direct quenching; carbon is diffused into the surface to give a hard case over a tough core. IT IS NOT STAINLESS. IT DOES NOT PRECIPITATION HARDEN; there is no H900 \/ H1025 \/ H1150 type ageing step.<\/div>\n
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Not to be confused with<\/div>\n

AISI 9310<\/a><\/div>\n<\/div>\n

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For what<\/div>\n
Bought for parts whose surface must resist wear while the body underneath takes impact: gears and ring-and-pinion sets, pinions, shafts and spindles, pins and bushings, chains and sprockets, hydraulic pump bodies, drilling and earth-moving components, plastic moulds.<\/div>\n<\/div>\n
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Forms<\/div>\n
Supplied as bar, flat bar, plate, sheet, tube and forgings.<\/div>\n<\/div>\n
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Standards<\/div>\n
AMS (verified, 0.50Cr – 0.55Ni – 0.20Mo, C 0.18-0.23% chemistry): 6274 (BARS, FORGINGS, MECHANICAL TUBING AND FORGING STOCK; AIRCRAFT QUALITY; latest revision S\/2021) \u00b7 6276 (same product forms; CONSUMABLE ELECTRODE VACUUM REMELTED – VAR) \u00b7 6277 (same product forms; VACUUM ARC OR ELECTROSLAG REMELTED – VAR or ESR) \u00b7 6375 (WELDING WIRE; vacuum melted; environment-controlled packaging). Heat treatment procedure: AMS 2759<\/b>\/7 (Carburizing and Heat Treatment of Carburizing Grade Steel Parts). Cleanliness: AMS 2300<\/b> \/ 2301 \/ 2304. ASTM: A29 \/ A29M (general requirements, hot-wrought alloy bars) \u00b7 A322 (alloy steel bars, standard grades) \u00b7 A331 (cold-finished bars) \u00b7 A506 (hot-rolled sheet and strip) \u00b7 A507 (cold-rolled sheet and strip) \u00b7 A513 (ERW mechanical tubing) \u00b7 A519 (seamless mechanical tubing) \u00b7 A534 (carburizing steels for anti-friction bearings) \u00b7 A646 (premium quality blooms and billets for aerospace forgings) \u00b7 A711 (stock for forgings) \u00b7 A752 (alloy steel wire rod) \u00b7 A829 (alloy structural steel plate). SAE: J404 (chemistry) \u00b7 J1268 (hardenability bands for H grades) \u00b7 J1397. EN and others: EN 10084 20NiCrMo2-2 (1.6523) and 20NiCrMoS2-2 (1.6526) \u00b7 BS 970 805M20 \u00b7 AFNOR 20NCD2 \u00b7 JIS SNCM220 \u00b7 SS 2506. Military: MIL-S-8690 (8620 bars, aircraft quality).
AMS 6274, 6276 AND 6277 ARE NOT INTERCHANGEABLE. All three share one chemistry and all three cover the same product forms (bars, forgings, tubing); THE DIFFERENCE IS THE MELTING METHOD.<\/span><\/div>\n<\/div>\n
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Advantage<\/div>\n
That one chemistry is covered on both the general-industrial and the aerospace side, and can be tied to numbers on both. On the industrial side the EN 10084 core table as printed by Saarstahl guarantees tensile strength by diameter after carburizing and tempering at 200 C: at least 1100 N\/mm2 up to\u2026<\/div>\n<\/div>\n
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Welding<\/div>\n
WELDABLE IN THE UNCARBURIZED (as-delivered) CONDITION. Its carbon is 0.18-0.23%, which makes it more amenable to welding than quench-and-temper grades such as 4140 or 8740.<\/div>\n<\/div>\n
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Limits<\/div>\n
1) IT IS NOT STAINLESS. Chromium is 0.40-0.60% and no passive layer forms. Without plating, phosphating, oil or paint it rusts in damp conditions; it is not suitable for marine or chloride-bearing environments.
\n2) IT DOES NOT HARDEN ON ITS OWN. Its carbon is 0.18-0.23%.<\/div>\n<\/div>\n
REQUEST A QUOTE<\/a>All alloy 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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