8620/8620H/21NiCrMo2/DIN1.6523/805 M20/EN362/SNCM 220H/SNCM 21 H/G8620 

Description:

8620 is a low nickel - chromium - molybdenum medium hardenability, case hardening (carburizing) steel, generally supplied in the as rolled condition with a maximum brinell hardness of 280 (Rc30).
Characterised by good core strength and toughness in small to medium sections with case hardness up to Rc62 when carburized, hardened and tempered.
8620 can also be used (uncarburised) as a high tensile steel, which when suitably hardened and tempered can be utilized for various applications requiring good tensile strength and reasonable toughness.
Pre hardened and tempered (uncarburized) 8620 can be further surface hardened by nitriding but will not respond satisfactorily to flame or induction hardening due to its low carbon content.
8620 (carburized) is used extensively by all industry sectors for light to medium stressed components and shafts requiring high surface wear resistance with reasonable core strength and impact properties.

APPLICATIONS:

AISI 8620 is a common, carburizing alloy steel used for a variety of medium-strength applications including gears, camshafts, fasteners, and chains/chain pins. Flexibility in hardening treatments allow optimization of case/core properties. Typical uses are: Arbors, Bearings, Bushings, Cam Shafts, Differential Pinions, Guide Pins, King Pins, Pistons Pins, Splined Shafts, Ratchets, Sleeves etc..

Related Specifications

Australia AS 1444-1996-8620/8620H

Germany W.Nr 1.6523 DIN 21NiCrMo2

Great Britain BS970: PART 3: 1991 805 M20

BS970: 1955 - EN362

Japan JISG 4052 SNCM 220H

JIS SNCM 21 , JIS SNCM 21 H

U.S.A. SAE 8620 AISI 8620

ASTM A29/A29M 1991 8620

UNS G86200

AMS 6274 , AMS 6274G , AMS 6276 , AMS 6276C , AMS 6277 , AMS 6277A ,

ASTM A322 , ASTM A331 , ASTM A505 , ASTM A513 ,

MIL SPEC MIL-S-16974 ,

SAE J404 , SAE J770 ,

UNS G86200

France: AFNOR 20 NCD 2 , AFNOR 22 NCD 2

Italy: UNI 20 NiCrMo 2

Chemical Composition(%):

Carbon 0.17-0.23

Silicon 0.10-0.40

Manganese 0.60-0.95

Nickel 0.35-0.75

Chromium 0.35-0.75

Molybdenum 0.15-0.25

Phosphorous 0.04 max

Sulphur 0.04 max

Colour Code:  Black (Bar end)

Process: EAF+LF+VOD+Forged or Rolled+Heat Treatment(optional)

SIZE RANGE:

Round:

Hot Rolled: 8mm-500mm

Hot Forged: 80mm -1200mm

Flat:

Hot rolled: Thickness: 20-130mm Width: less than 610mm

Hot forged: Thickness: 150-600mm Width: up to 1600mm

SURFACE FINISHES:

Black, Peeled (K12), Cold Drawn, Turned & Polished (H10, H11), Precision Ground (H9, H8)

Test: Ultrasonic test according to SEP 1921-84 3C/c

Forging
Heat to 1150 oC and hold until temperature is uniform throughout the section. Soaking time at forging temperature should be as short as possible to avoid heavy scaling and excessive grain growth. This will vary depending on furnace conditions but 15 minutes per 25 mm of section may be used as a guide.Do not forge below 850 oC.
Following completion of forging operation, work piece should be cooled as slowly as possible in sand or dry lime etc.
Note: Case hardening steels due to their low carbon content are less susceptible to cracking than medium or high carbon steels, and may therefore be heated and cooled more rapidly.

Machining
8620 in the as rolled as supplied condition, has very good machinability and all operations such as turning, drilling, milling and tapping etc. can be carried out satisfactorily as per machine manufacturers recommendations for suitable tool type - feeds and speeds.

Welding
8620 is readily weldable in the as rolled as supplied condition. Following welding, the work piece immediately upon cooling to hand warm should be stress relieved at 630 oC - 650 oC if possible.
N.B. Welding in the carburized and heat treated condition is not recommended.
Welding Procedure
Welding of 8620 should always be carried out using low hydrogen electrodes - please consult your welding consumables supplier.

Certificate of Quality: issued in English, in addition the normal terms, production process, the mechanical property (yield strength, tensile strength, elongation and hardness), forged ratio, UT test result, Grain size, heat treatment methods and the sample of is shown on the Certificate of Quality.

Marking: Heat No. will be cold stamped and Steel grade, diameter (mm), length (mm), and the manufacturer LOGO and weight (kg) is painted