AISI 8620 STEEL BUYING GUIDE
Are you worrying about finding suitable gear materials? Congratulations, you have found the right place.
Here, we will introduce to you AISI 8620, a gear steel with excellent performance, including its basic knowledge, main features, performance and other useful information.
Through this guide, we believe that it can help you solve problems and gain self-confidence.So, what are you waiting for? Let’s start!
WHAT DOES AISI 8620 MEAN?
In the market, we can often see AISI 8620 or SAE8620, in fact, they all refer to 8620 steel,the difference is that one is named by the American Iron and Steel Institute (AISI) and the other is named by the Society of Automotive Engineers (SAE).They jointly developed and shared a set of steel grade numbering system:Unified Numbering System,referred to as UNS.Here,we can find UNS G86200, it is the number for 8620 steel.
For 8620, The first number ‘8’ indicates that the steel is Nickel Chromium Molybdenum Steel,and 86XX means 0.5%Ni,0.5%Cr,0.2%Mo.
The last two numbers ‘20’ indicates the amount of carbon present in the steel. For this grade it has 0.20% carbon same as AISI 1020 steel.
In 86XX series,besides 8620 steel,8622 and 8625 is also commonly used in the industry,we can the difference in composition in the following table
WHAT IS CASE HARDENING STEEL?
In sliding contact with hard or abrasive materials, the wear of steel materials is inevitable in daily use. How to slow down its wear? After continuous practice, increasing the surface hardness is an effective way to effectively resist surface wear. This is the origin of case hardening steel.
From the EN10084 standard, case hardening steel refers to steels with a relatively low carbon content which are intended for carburising or carbonitriding and subsequent hardening.In the standard, we can clearly see that carbon steel and alloy steel are suitable for case hardening, and the amount of carbon is less than 0.3%.
Types of Case Hardening Methods
- Flame or induction hardening
The significant difference between Flame or Induction hardening and the last three methods is that Flame or Induction Hardening does not change the chemical composition of the material, which is just a topical heat treatment process, so it is usually only suitable for high carbon steel having sufficient reaction to quenching.
QUICK FAQS FOR AISI 8620 STEEL
Is AISI 8620 Steel Gear Steel?
Yes,AISI 8620 steel, as a CR-Ni-Mo series case hardening steel, is widely used in carburizing and carbonitriding process,and commonly used in the manufacture of gears in the engines and transmission systems of small and medium-sized cars and tractors.
What is AISI 8620H?
In fact, there is no difference in chemical composition between 8620H and 8620.While add ‘H’, this means that 8620 steel is required to ensure hardenability.
Can AISI 8620 Steel be Cold Drawn?
AISI 8620, as a low-carbon low-alloy steel, has higher strength than ordinary low-carbon steel, and good plasticity and toughness.
Yes, it can be cold drawn,and it is better to do cold drawing after annealing.After cold drawing, AISI 8620 steel has a smooth surface and precise dimensions, which is suitable for further processing, such as carburizing.
How Hard is AISI 8620 Steel？
AISI 8620, as a low-carbon alloy steel, under conventional heat treatment, such as annealing and normalizing, the hardness is generally not high, less than 200HBW.
But after carburizing and quenching, it has a very high hardness value, reaching 60HRC, and the core reaches about 35HRC,which is suitable for working under heavy load and impact.
Is AISI 8620 Same as 20NiCrMo2-2?
Although their chemical compositions are very similar, they are equivalent grades. AISI 8620 is the grade of the American standard ASTM A29, while 20NiCrMo2-2, also refers to DIN 1.6523, comes from the EN10084 European standard.
Other Equivalent Grade
China/GB 3077: 20CrNiMoA
Japan/JIS G4103: SNCM220
HEAT TREATMENT FOR AISI 8620 STEEL
AISI 8620 Normalizing & Annealing
- Process comparison
|AISI 8620 Normalizing||AISI 8620 Annealing|
|Cooling||Air Cooling||Furnace Cooling|
|Cooling Speed Rate||Relatively fast||Slow|
|Heat Treatment Cycle||Short time||Long time|
- Mechanical Properties
|Tensile Strength||Yield Strength||Elongation||Reduction of Area||Impact Charpy-V||Hardness|
How to Carburize AISI 8620 Steel？
- AISI 8620 Isothermal Normalizing
Before carburizing AISI 8620 steel, it is first subjected to isothermal normalizing as a preliminary heat treatment.The purpose is to eliminate or improve various structural defects caused by hot working, obtain easy-to-cut microstructure and hardness, improve microstructure and distribution, refine grains, and prepare microstructure for the carburizing and quenching process.
AISI 8620 steel requires a hardness of HB156-207 after isothermal normalizing, and the structure is uniform pearlite plus ferrite. Generally, normalizing tends to appear bainite structure, which leads to material brittleness and higher hardness, which is not conducive to cutting. Therefore, the isothermal normalizing process should suppress the appearance of bainite structure.
The previous steps of AISI 8620 steel isothermal normalizing, such as heating temperature and holding time are the same as ordinary normalizing.After the heat preservation is completed, cool to an isothermal temperature of about 700℃, so that the supercooled austenite is transformed in this temperature range, and a finer (relative to isothermal annealing) pearlite structure is obtained, finally air-cooled.
- AISI 8620 Carburizing
The carburizing and quenching process of AISI 8620 steel can be carburized with slowly cooling, followed by secondary heating and quenching & tempering. This method can refine the grains, reduce the amount of retained austenite after quenching, increase the quenching hardness, increase the strength of the carburized layer, and reduce deformation.
Surface Hardness: above 58HRC
Effective Case Hardened Layer Depth: 1.7-2.1mm
AISI 8620 VS 17CRNIMO6
First of all, they are all case hardening steel. The difference is that AISI 8620 comes from the American standard, and 17CrNiMo6,also refers to 18CrNiMo7-6(EN10084 Standard), belongs to the grade in the German DIN17210 standard.Next, let’s briefly discuss the difference between these two steel grades.
- Chemical Composition
From the above table,we can see that although they are both low-carbon alloy steels, the difference in the elemental composition of Cr Ni Mo is still very obvious.Due to these differences, the manufacturing cost is obviously higher than 8620 steel.
- Hardenability Limits
|Distance from quenched end mm||1.5||3||5||7||9||11||13||15||20||25||30||35||40|
From the above table of end quenching test,We can clearly see the difference in data between AISI8620 and 17CrNiMo6. It can be said that the hardenability of 17CrNiMo6 is significantly better than AISI 8620 steel.Therefore, when we choose an application, we should fully consider the properties of the material to make the best use of it.
- Industrial Application
As a representative of the Cr-Ni-Mo series, in the automotive field, the American standard AISI 8620 steel is usually used in light and medium-sized vehicles to meet the requirements of the use of small and medium-sized modular gear steels, while the German standard 17CrNiMo6 steel is used in heavy vehicles. It is suitable for manufacturing large-modulus and heavy-duty automobile gears.
17CrNiMo6 Gears For Further Processing
WHERE CAN YOU BUY HIGH-QUALITY AISI 8620 STEEL?
With rich manufacturing experience for more than 15 years in the field of special steel manufacturing,Waldun Steel can not only manufacture high-quality AISI 8620 steel, but also provide one stop service solution,including heat treatment,machining and cutting.When you are looking for AISI 8620 steel, Waldun will always be your best choice.
What We Supply For AISI 8620 Steel
|Φ6-Φ100||Cold Drawn||Bright/Black||Best H11|
What Size We stock For AISI 8620 Steel
- Hot Rolled Round Bar:Φ16-Φ300mm,7 Days Delivery
- Hot Forged Round Bar:Φ140-Φ250mm,15 days Delivery
- Customized service：Special Size & Length,30 days Delivery
- Free Sample of AISI 8620 Steel