8620 Equivalent Material — Case-Hardening Steel Grade Chart: 16MnCr5, 20MnCr5, 20NiCrMo2-2, SCM420, 20CrMnTi

The Crosswalk — 30 Case-Hardening Steels Across AISI, EN, DIN, BS, JIS and GB

Of the 30 grades in the crosswalk, 4 pairs are direct equivalents whose composition bands overlap on every element, 21 are nearest equivalents that differ in at least one band, and 5 are substitutes with no counterpart listed in any other system. The European names are those of EN ISO 683-3 (formerly EN 10084): EN 10084:2008 was withdrawn in 2018 and replaced by EN ISO 683-3, whose 2016 edition deleted 14NiCrMo13-4 and 20NiCrMo13-4 and whose 2022 edition added 23MnCrMo5-5-4 and 17NiCrMoS6-4, so 14NiCrMo13-4 survives only in the withdrawn EN 10084:2008. Compositions come from the EN 10084:2008 tables (steelnumber, Ovako), SAE J403 / J404 (eFunda), JIS G4053 (steeljis, kikakurui), GB/T 3077 and BS 970; the GB/T 5216 H-grades and the JIS pairings follow ISO 683-3 Annex B; a blank cell means no source lists a counterpart, and the cell stays blank rather than guessed.

EKINSUN LTD machines gears, pinions, pulleys, sprockets, cams, shafts and pins in 8620 / 20NiCrMo2-2, 16MnCr5, 20MnCr5, SCM420 and 20CrMnTi from one piece, carburised to the drawing’s case depth, hardened and finish-ground — from a drawing, a sketch or the worn part.

15CrNi6 (1.5919) is no longer in EN 10084:2008; its successor 17CrNi6-6 (1.5918) is shown in that row. 805M20, 527M17, 590M17, 080M15, SNCM220, SCr420, 20Cr, 20CrMo, 20CrNiMo and 15NiCr13 appear inside the rows of their AISI, EN or BS twins rather than as rows of their own. 18CrNiMo7-6 has no BS 970 counterpart in EN 10084 Annex D; the 820A16 quoted by steelnumber is not confirmed and the cell stays blank.

Composition Ranges — the Bands Behind Each Name (mass %)

Every grade in the chart has a carbon ceiling of 0.25 % — 42CrMo4 starts at 0.38 % — and the bands below are what a buyer compares element by element before calling two grades equivalent. The standard column names the table each band was copied from: SAE J404 for the AISI alloy grades, SAE J403 for the plain carbon grades, the EN 10084:2008 tables for the European names (now EN ISO 683-3), JIS G4053, GB/T 3077 and BS 970 for the rest. Hardenability follows Mn, Cr, Ni and Mo together, so a grade that matches on carbon alone is not a match.

Si for the SAE J403 carbon grades and UNS for 9310 are left blank because the sources do not list them; Si 0.15–0.35 % on the ten SAE J404 alloy rows is the J404 range for standard alloy steels (older eFunda tables print 0.15–0.30 %). Cr for 835M15 reads “not sourced”: West Yorkshire Steel and Hillfoot both call it a nickel-chromium-molybdenum steel, but neither prints a chromium range. The 655M13 columns are the BS 970 655M13 specification (C 0.10–0.16 %, Mn 0.35–0.60 %, Cr 0.70–1.00 %), not the older BS 970:1955 EN36 blanket range of C 0.12–0.18 %, Mn 0.30–0.60 %, Cr 0.60–1.10 % still quoted on stockholder EN36 pages. P and S limits: 0.035 / 0.040 % max for the 86xx grades, 0.025 % max in 9310, 16MnCr5 and 20MnCr5, 0.030 % max in the JIS grades.

What “Equivalent” Means Here — Direct, Nearest, Substitute, and Four Traps

A direct equivalent is a pair that a standards database (steelnumber, eFunda) lists together and whose composition bands overlap on every alloying element, so a part made in either steel hardens to the same case and a comparable core: 8620 and 20NiCrMo2-2 (Cr 0.40–0.60 % against 0.35–0.70 %, Ni 0.40–0.70 % in both) is the model case. A nearest equivalent is the closest grade the other system has, with at least one band clearly off — the row says which element, and that element decides whether the swap is safe in your section size. A substitute is a grade no database pairs with anything: it can stand in for the same duty after a hardenability check, never by name alone.

Which Grade for Which Part — Section Size Decides

A carburised case reaches 58–62 HRC in every grade of the chart; what the grade buys is the depth to which the core under that case hardens, and that depth grows with Mn, Cr, Ni and Mo together — from 5115 (Cr 0.70–0.90 %, nothing else) through 16MnCr5 (Mn 1.00–1.30 %, Cr 0.80–1.10 %) and 8620 (Ni 0.40–0.70 %, Mo 0.15–0.25 %) to 18CrNiMo7-6 (Cr 1.50–1.80 %, Ni 1.40–1.70 %, Mo 0.25–0.35 %). The table pairs the part with the grades that carry it in each naming system.

Grades for a new design follow the same logic from the other end: an engineer who specifies 16MnCr5 for a 20 mm pinion and 18CrNiMo7-6 for the 200 mm wheel it drives is buying core depth where the tooth root needs it. Gear geometry itself — module, tooth count, keyway to DIN 6885 — is set on the custom spur gear and gearbox parts pages.

How Case Hardening Is Specified — CHD, Surface and Core Hardness

Case hardening depth is written on a European drawing as CHD to ISO 2639: the depth below the surface at which a Vickers hardness profile on a cross-section falls to 550 HV1, so “CHD 550 1,0–1,5” means that limit lies between 1.0 and 1.5 mm. The rows below carry the numbers a shop and a heat-treater need to agree on before the first part goes into the furnace.

Two consequences for the order. Carburising sits between roughing and finishing, so a drawing for a carburised part needs a grinding allowance on the bore and the running faces and a datum that survives the quench; and CHD is a destructive measurement, so a test coupon of the same grade travels with the batch when the drawing asks for proof. The heat-treatment sequence for machined parts — soft machining, carburise, harden, temper, grind — is laid out on the heat treatment and machining page.

Where the Chart Stops — Bar From Stock, Parts From a Drawing

Bar in 8620, 16MnCr5, 20MnCr5 and SCM420 is a stock item at every steel stockholder, and the chart above is how you order the right one; a gear, pinion, pulley, sprocket, cam, shaft or pin in that grade with a stated CHD is not on any shelf. The table is plain about which is which.

Requests arrive in both directions. From a maintenance buyer: “we are looking at making discontinued parts for our multi-head embroidery machine, the part is most likely AISI 8620 case-hardened, 20–30 pieces.” From a purchaser with a European drawing: “the drawing says 16MnCr5, CHD 0.8, our supplier only stocks 8620 — is that the same?” The first gets the part measured from the sample and made in 8620 / 20NiCrMo2-2 (see embroidery machine parts and parts from a sample); the second gets a straight answer — 8620 hardens deeper than 16MnCr5 through its Ni 0.40–0.70 % and Mo 0.15–0.25 %, so for CHD 0.8 on a small gear it is a safe upward substitute, and the certificate names the grade actually used. Worn bearing seats and races, pulleys and sprockets follow the same route; a hand sketch with the main dimensions is enough to start.

Quick Answers

What is the European equivalent of 8620?

8620 is 20NiCrMo2-2, material number 1.6523, in EN ISO 683-3 (formerly EN 10084), old DIN 21NiCrMo2; the bands overlap on every element (8620: C 0.18–0.23 %, Cr 0.40–0.60 %, Ni 0.40–0.70 %, Mo 0.15–0.25 %; 20NiCrMo2-2: C 0.17–0.23 %, Cr 0.35–0.70 %, Ni 0.40–0.70 %, Mo 0.15–0.25 %). BS 805M20 and JIS SNCM220 are the same steel; GB/T 5216 20CrNiMoH is listed as identical in ISO 683-3 Annex B, and GB/T 3077 20CrNiMo (Mo 0.20–0.30 %, Ni 0.35–0.75 %) is the same steel with slightly shifted band limits.

What is 16MnCr5 in AISI?

16MnCr5 has no exact AISI grade; SAE 5115 is the cross-reference, with Mn 0.70–0.90 % and Cr 0.70–0.90 % against 16MnCr5’s Mn 1.00–1.30 % and Cr 0.80–1.10 %, so 5115 hardens less deeply. 8620 is the usual US substitute above about 25 mm section; 590M17 is the BS twin (EN 10084 Annex D) and GB/T 5216 16CrMnH the identical Chinese grade (ISO 683-3 Annex B).

Is 20MnCr5 the same as 5120?

No: 20MnCr5 (1.7147) carries Mn 1.10–1.40 % and Cr 1.00–1.30 %, SAE 5120 Mn 0.70–0.90 % and Cr 0.70–0.90 %, at the same carbon 0.17–0.22 %. Both carburise to 58–62 HRC; 20MnCr5 keeps a hard core deeper into the section.

What is SCM420 equivalent to?

JIS SCM420 (Cr 0.90–1.20 %, Mo 0.15–0.25 %) is nearest to EN 18CrMo4 / 1.7243 (C 0.15–0.21 %, Cr 0.90–1.20 %, Mo 0.15–0.25 %, paired with SCM418 in ISO 683-3 Annex B) and to GB 20CrMo (Mn 0.40–0.70 %, Cr 0.80–1.10 %); the AISI cross-reference 4118 has only Cr 0.40–0.60 % and Mo 0.08–0.15 %. 8620 is the closer US grade in hardenability.

What is 20CrMnTi equivalent to?

GB 20CrMnTi (C 0.17–0.23 %, Mn 0.80–1.10 %, Cr 1.00–1.30 %, Ti 0.04–0.10 %) is nearest to 20MnCr5 (Mn 1.10–1.40 %, Cr 1.00–1.30 %, no Ti) and is listed by steelnumber under both 20MnCr5 and 16MnCr5. 5120 is sometimes substituted and is not equivalent. Typical treatment: carburise 900–930 °C, re-austenitise 820–850 °C, temper 150–200 °C, case 0.8–2.0 mm, surface 58–62 HRC, core 28–35 HRC.

Is 4140 a case-hardening steel?

No. 4140 has C 0.38–0.43 % and 42CrMo4 0.38–0.45 %; both are quenched-and-tempered or induction-hardened steels, not carburising grades, which stay below about 0.3 % C. A 4140 part gets its surface hardness from induction hardening to 53 HRC minimum, not from a carburised case.

What does CHD 0.8 mean on a drawing?

A case hardening depth of 0.8 mm to ISO 2639: the Vickers profile on a cross-section must stay above 550 HV1 down to 0.8 mm below the surface. The US effective case depth is measured to 50 HRC instead, so the two conventions give different numbers for the same part.

Related charts: bolt grade chart (property classes 4.6–12.9 and the 42CrMo4 / C45 behind them), carbon steel machining, and the full materials list.

Case-Hardening Steel FAQ