AISI 8620 Alloy Steel Material Specifications

 

  • Introduction
  • Chemical Composition
  • Mechanical Properties
  • Other Designations (equivalent materials)
  • Principal Design Features
  • Applications
  • Machinability
  • Forming
  • Welding
  • Heat Treatment
  • Forging
  • Hot Working
  • Cold Working
  • Annealing
  • Aging
  • Tempering
  • Hardening
  • Other Comments
  • Disclaimer

Introduction [i]

AISI 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.Typical uses are: Arbors, Bearings, Bushings, Cam Shafts, Differential Pinions, Guide Pins, King Pins, Pistons Pins, Splined Shafts, Ratchets, Sleeves etc…

 

Chemical Composition [ii]

The following table shows the chemical composition of AISI 8620 alloy steel.

Element Content (%)
Iron, Fe 96.895-98.02
Manganese, Mn 0.700-0.900
Nickel, Ni 0.400-0.700
Chromium, Cr 0.400-0.600
Carbon, C 0.180-0.230
Silicon, Si 0.150-0.350
Molybdenum, Mo 0.150-0.250
Sulfur, S ≤ 0.0400
Phosphorous, P ≤ 0.0350

Physical Properties

The physical properties of AISI 8620 alloy steel are outlined in the following table.

Properties Metric Imperial
Density 7.85 g/cm3 0.284 lb/in³

Mechanical Properties

The mechanical properties of annealed AISI 8620 alloy steel are outlined in the table below.

Properties Metric Imperial
Tensile strength 530 MPa 76900 psi
Yield strength 385 MPa 55800 psi
Elastic modulus 190-210 GPa 27557-30458 ksi
Bulk modulus (typical for steel) 140 GPa 20300 ksi
Shear modulus (typical for steel) 80 GPa 11600 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Izod Impact 115 J 84.8 ft.lb
Hardness, Brinell 149 149
Hardness, Knoop (converted from Brinell hardness) 169 169
Hardness, Rockwell B (converted from Brinell hardness) 80 80
Hardness, Vickers (converted from Brinell hardness) 155 155
Machinability (hot rolled and cold drawn, based on 100 machinability for AISI 1212 steel) 65 65

Thermal Properties

The thermal properties of AISI 8620 alloy steel are highlighted below.

Properties Metric Imperial
Thermal conductivity 46.6 W/mK 323 BTU in/hr.ft².°F

Other Designations

Equivalent materials to AISI 8620 alloy steel are outlined in the table below.

AISI 8620 AMS 6274 AMS 6276 AMS 6277 AMS 6375 ASTM A29
ASTM A322 ASTM A331 ASTM A506 ASTM A507 ASTM A513 ASTM A519
ASTM A646 ASTM A752 ASTM A829 MIL S-8690 SAE J1397 SAE J404
AFNOR 20 NCD 2 AFNOR 22 NCD 2 DIN 1.6523 UNI 20 NiCrMo 2 JIS SNCM 21 JIS SNCM 21 H
B.S. 805 H 20 B.S. 805 M 20 AMS 6274G AMS 6276C AMS 6277A ASTM A505
MIL SPEC MIL-S-16974 SAE J404 SAE J770

 

Principal Design Features AISI 8620 is a hardenable chromium, molybdenum, nickel low alloy steel often used for carburizing to develop a case-hardened part. This case-hardening will result in good wear characteristics.
 

 

 

Applications In the carburized condition this alloy is used for gears, ring gears, shafts and crankshafts, machine parts subject to mechanical wear.

 

Machinability Machining is done prior to carburizing to within as close a tolerance as possible. Finish machining, after heat treatment and/or carburizing, should be at a minimum so as not to impair the hardened case of the part. Machining may be done by conventional means prior to heat treatment – after carburizing machining is usually limited to grinding.

 

Forming Forming characteristics of 8620 alloy are good in the annealed condition.

 

Welding 8620 is readily weldable in the as rolled as supplied condition. The alloy may be welded by conventional methods, usually gas or arc welding. Preheating at 400 F (204 C) is beneficial and subsequent heating after welding is recommended. Following welding, the work piece immediately upon cooling to hand warm should be stress relieved at 630oC – 650oC if possible.

N.B. Welding in the carburized and heat treated conditions not recommended.

Consult the approved weld procedure for the method used.

 

Heat Treatment This alloy may be hardened by heating to 1500 F followed by a water quench. Carburize at 1650 to 1700 F in an appropriate carburizing medium and oil quench to harden. Improved carburized case and core properties can be obtained by furnace cooling from carburizing at 1650 – 1700 F and then reheating to 1575 F.

 

Forging The alloy may be forged at 2200 F down to 1800 F prior to the hardening heat treatment or carburizing.

 

Hot Working Hot working may be accomplished prior to hardening or carburizing. Consult the alloy supplier for information as to temperatures.

 

Cold Working The alloy may be cold worked in the annealed condition by conventional methods. Cold working, as with machining, should be done to as close a tolerance as possible before heat treatment or carburizing.

 

Annealing AISI 8620 may be given a full anneal at 1550 F and slow cooling at not more than 50 F per hour down to 850 F. From there it may be air cooled.

 

Aging Not applicable to this alloy.

 

Tempering Tempering of carburized parts is done at 250 to 300 F and this will result in the alloy having a core strength of approximately 135 ksi minimum with Rockwell C case hardness of 90. Tempering of heat treated and water quenched parts (not carburized) is done at 400 F to 1300 F with greater hardness the lower the tempering temperature.

 

Hardening Hardening is done by oil quench from 1675 F. See “Heat Treatment”. Carburizing is accomplished at the same 1650 to 1700 F range in a carburizing “pack” or environment, followed by oil quench for thin sections or a furnace cool for heavier (over 3/4″) sections. Following carburizing of heavy sections a reheat at 1575 F will enhance both case and core properties of the alloy.

 

Other Comments This alloy is typically used for carburized parts where a hardened case is desired for wear resistance.

Extremal links

 

Disclaimer
This information is provided “as is” and HddJetNozzle/Cherrington LLC (HDDJN/CLLC) makes no warranty of any kind with respect to the subject matter or accuracy of the information contained herein. HDDJN/CLLC specifically disclaims all warranties, expressed, implied or otherwise, including without limitation, all warranties of merchantability and fitness for a particular purpose.

HDDJN/CLLC neither makes nor endorses any representations as to the suitability of any material as it relates to the design needs and criteria of the end user. All steel and/or alloy Mechanical Properties data sheets are for reference only as widely available in published AISI & SAE standards and specifications.

In no event shall HDDJN/CLLC be liable for any special, incidental, indirect or consequential damages of any kind or any damages whatsoever resulting from loss of use, data, profits, whether or not advised of the possibility of damage, and on any theory of liability, arising out of or in connection with the use of the information contained herein.

This publication may include technical inaccuracies or typographical errors. Changes may be periodically made to the information herein.

Chemical Composition(s) for materials used to manufacture the parts referenced in this website and/or by the Seller can be obtained by the Buyer requesting from the Seller a (lot specific) “Material Test Report”.

Citations / Credits

[i] Interlloy Pty Ltd

[ii] AZOM Materials

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