English
You are here: Home » Products » Other Stainless Ball » Alloy Steel Balls

Alloy Steel Balls Manufacturer – Custom 40Cr & SAE 8620

RISHENG manufactures custom 40Cr, SAE 8620 and CG08 alloy steel balls for applications requiring wear resistance, impact toughness and controlled hardness.
Quenched-and-tempered 40Cr steel balls provide balanced hardness and toughness, while carburized SAE 8620 balls combine a hard, wear-resistant surface with a tougher core. Ball diameter, precision grade, hardness, case depth and surface finish can be matched to the application.
40Cr alloy steel balls G10 precision

What Are Alloy Steel Balls?

short cycle press machnie
Alloy steel balls are spherical components made from steels containing alloying elements such as chromium, nickel or molybdenum. Their performance depends on the steel grade, heat treatment, finished size and surface quality.

40Cr and SAE 8620 have different hardening characteristics. 40Cr is commonly quenched and tempered, while SAE 8620 is commonly carburized, quenched and tempered to develop a hard outer case.

Chemical Composition of 40Cr, SAE 8620 and CG08 Alloy Steel Balls

Chemical Composition

  C Si Mn Cr Ni P S
CG40Cr 0.37-0.44% 0.17-0.37% 0.50-0.80% 0.80-1.10% ≤0.30% ≤0.035% ≤0.035%
CG08 0.06-0.10% 0.10-0.30% 0.30-0.60% 0.50-0.80% ≤0.20% ≤0.030% ≤0.030%
SAE 8620 0.18-0.23% 0.15-0.35% 0.70-0.90% 0.40-0.60% 0.40-0.70% ≤0.035% ≤0.040%

40Cr vs SAE 8620: Heat Treatment and Hardness

Material Heat-treatment route Hardness reference
40Cr Quenching and tempering Approximately HRC 28–55 across different tempering conditions
SAE 8620 Carburizing, quenching and tempering Surface HRC 58–62 is a common carburized target

Alloy Steel Ball Physical Properties

Item Parameters
Elastic Modulus 200-210 GPa
Thermal Conductivity 40-45 W/(m·K)
Coefficient of Thermal Expansion 11.5-12.5 (10⁻⁶/°C) 
Density 7.85 g/cm³
Hardness — 52100/GCr15 HRC 60 – 66, through-hardened
Hardness — SAE 8620 Surface HRC 58 – 62 after carburizing, tough core
Hardness — 40Cr HRC 28 – 55 by tempering temperature

Alloy Steel Ball Physical Properties

Grade Maximum single-ball diameter variation V_Dws (µm) Maximum lot diameter variation V_DwL (µm) Maximum surface roughness Ra (µm)
G10 0.25 0.50 0.020
G16 0.40 0.80 0.025
G20 0.50 1.00 0.032
G28 0.70 1.40 0.050
G40 1.00 2.00 0.060
G60 1.50 3.00 0.080
G100 2.50 5.00 0.100
G200 5.00 10.00 0.150

NOT SURE WHICH ALLOY STEEL BALL IS RIGHT FOR YOU?

Alloy Steel vs Carbon Steel vs Stainless Steel Balls: Which to Choose?

line
Property Alloy Steel (40Cr/8620) Carbon Steel Balls 420 Stainless Steel Balls 304/316 Stainless Balls
Wear resistance Excellent Very good Good Fair
Corrosion resistance Low (oil protection needed)  Low Moderate Excellent
Load capacity Highest High Medium Low–Medium
Best for Bearings, grinding, valves Casters, slides Mild-corrosive bearings Food, medical, marine
line

Applications of Alloy Steel Balls

line
Grinding Media for paint, ink and pigment attritors (not forged mining balls
Heat-treated chrome alloy steel balls with hardness up to approximately HRC 60–66 are used as grinding media in ball mills, attritors and industrial milling equipment. Typical materials processed include paints, inks, pigments, minerals and other abrasive powders. Their high hardness and wear resistance help extend media life under demanding milling conditions.

Check Valves, Hydraulic Systems and Pumps
Precision alloy steel balls serve as closing and sealing elements in check valves, hydraulic circuits, pumps, dosing systems and other flow-control equipment. Controlled ball diameter, sphericity and surface finish help reduce leakage, maintain consistent flow and improve service life.Hardened alloy steel is suitable for lubricated and non-corrosive environments. Stainless steel, ceramic or coated balls are recommended for water, chemicals and corrosive fluids.

Automotive and Transmission Components
Carburized SAE 8620 steel balls provide a hard, wear-resistant surface supported by a tough core. They can be used in selected gearboxes, steering mechanisms, seat-slide systems and automotive safety components exposed to shock loads and repeated contact stress.Quenched-and-tempered 40Cr alloy steel balls offer a balanced combination of strength, fatigue resistance and impact toughness. Induction hardening can be specified when greater surface wear resistance is required.

Mining, Conveyors and Heavy Industrial Machinery
Heat-treated alloy steel balls are suitable for selected mining machinery, conveyor systems, heavy-duty slides, locking mechanisms and industrial equipment operating under high loads, vibration and abrasive conditions. Compared with ordinary low-carbon steel balls, properly treated alloy steel balls provide better resistance to wear, deformation and premature failure.
precision steel balls check valves
 

 
mining conveyor alloy steel balls
 

 
automotive transmission alloy steel balls
 

Why Choose RISHENG as Your Alloy Steel Ball Manufacturer

line
SAE 8620 carburized alloy steel balls
High hardness and wear resistance — quenched-and-low-tempered 40Cr alloy steel balls typically achieve a through hardness of HRC 50–55. Carburized, quenched and tempered SAE 8620 steel balls achieve a surface hardness of HRC 58–62, while retaining a tough core of approximately HRC 30–45. This hard-surface/tough-core structure provides excellent resistance to contact wear, shock and surface fatigue.
High fatigue strength and impact toughness — 40Cr balls provide balanced strength and through-hardness, while carburized SAE 8620 balls combine a wear-resistant case with a ductile core. They are suitable for high-frequency cyclic loads and impact applications, including automotive transmissions, CV joints, ball joints, heavy-duty machinery and industrial drive components.
Controlled precision and surface finish — available in precision grades G10–G200 according to ISO 3290-1. Depending on the selected grade, the maximum ball diameter variation ranges from 0.25 μm for G10 to 5 μm for G200, while the maximum surface roughness ranges from Ra 0.020 μm to Ra 0.150 μm. Grade, surface finish and gauge sorting can be selected according to the required load, speed and operating accuracy.

Custom diameters from 0.5 mm to 100 mm — as an alloy steel ball manufacturer, we can customize the ball diameter, material, hardness, carburized case depth, precision grade and surface finish. Available size and grade combinations depend on the selected alloy, heat-treatment process and application requirements.

Know Detailed Information

Please Download Catalogue Here 
alloy steel ball catalogue download

Alloy Steel Ball Manufacturer — Our Factory

Short-Cycle-Press-Machine

Changzhou Risheng Steel Ball Co., Ltd. is located in Wujin District, Changzhou, in the Taihu Lake region within two hours of Shanghai. Founded in June 1995, the company specializes in the R&D, manufacturing and export of precision steel balls. Building on the technical foundation of the Wujin Metal Ball Research Institute, Risheng primarily produces bearing steel balls (AISI 52100), stainless steel balls (AISI 201/304/316/420/430/440) and carbon steel balls (AISI 1015/1045/1085) in diameters from 0.8 mm to 25.4 mm, in precision grades from G100 up to G10. We also supply custom alloy steel balls from 0.5 mm to 100 mm, as well as copper balls, flying saucer steel balls, ceramic balls and other special metal balls.

Packaging & Delivery of Alloy Steel Balls

Short-Cycle-Press-Machine

1. Rust-Preventive Protection
Rust-preventive oil and moisture-resistant packaging help protect 40Cr and SAE 8620 steel balls during storage and transport. Tell us if the preservation method must meet cleaning, assembly or oil-compatibility requirements.

2. Protective Inner Packaging
Inner packaging is selected according to ball size, weight and surface requirements. Where contact marks are unacceptable, specify separated packing or additional surface protection.

3. Export Outer Packaging
Cartons, drums and pallet arrangements are selected according to shipment weight and handling requirements. Confirm pack weight and shipping marks when placing the order.

4. Batch Labels and Identification
Specify the material grade, nominal diameter, precision grade, quantity and batch information required on the labels. Customer part numbers and barcode requirements can be reviewed with the order.

Service Process
line
You can expect sound service from risheng service technicians when and where you need it most. From our application insight to our confidence at the counter, risheng will work to answer your requests with expert care and promptness. We know you better than anyone .
  • 1
    Specification Review
    Precision-manufactured alloy steel balls with tightly controlled heat treatment for consistent hardness and wear resistance in demanding applications.
  • 2
    Production and Quality Inspection
    Every batch is inspected for diameter, roundness, surface finish and hardness, with mill test certificates available for full traceability.
  • 3
    Export Packaging and Delivery
    Fast quotations, flexible custom production, global logistics and responsive after-sales service to keep your production running.​​​​​​​
Quality Certification
Short-Cycle-Press-Machine
3
QQ_1757510237965
未标题-3
未标题-4
未标题-5
未标题-7
ISO 9001 2015 quality management system certificate for Changzhou Sunrise Ball Co., Ltd.

FAQ of Alloy Steel Balls

  • Q Can alloy steel balls be used at high temperatures?

    A
    Only within limits. A hardened alloy steel ball starts to lose hardness if its service temperature approaches the temperature at which it was tempered. Low-temperature-tempered 40Cr and carburized SAE 8620 balls should be kept well below their tempering temperature. If your ball will run continuously above about 150 °C, tell us the working temperature so we can adjust the heat treatment or suggest another material.

     

  • Q Should I choose alloy steel balls or bearing steel (52100) balls?

    A Choose bearing steel balls when you need the highest rolling fatigue life in ball bearings; 52100 balls are through-hardened to HRC 60–66. Choose alloy steel balls when your part needs a different balance: tougher cores for shock loads (SAE 8620), lower cost for wear parts (CG08), or larger sizes and adjustable hardness (40Cr).

  • Q Are alloy steel balls suitable for water or corrosive fluids?

    A
    No. Alloy steel balls are not stainless and will rust in water, humidity or corrosive media. They are supplied lightly oiled and should be used in lubricated, non-corrosive conditions such as gearboxes, hydraulic oil and greased mechanisms. For wet or corrosive service, choose stainless steel balls, or ask about electroplated alloy steel balls for added surface protection.

     

  • Q What sizes can you make?

    A
    Alloy steel balls are available from 0.5 mm to 100 mm, in metric and inch sizes. Precision grades G10–G200 apply to the smaller size range; large balls are supplied to the grade agreed on the drawing. Send us the diameter, grade and quantity and we will confirm feasibility.

     

  • Q What is the difference between 40Cr and SAE 8620 steel balls?

    A 40Cr is hardened through the whole ball, while SAE 8620 is hardened only on the surface.
    - 40Cr: quenched and tempered to about HRC 28–55 depending on tempering temperature. The hardness is uniform from surface to core, so the ball keeps working even after surface wear.
    - SAE 8620: carburized to a surface hardness of HRC 58–62 with a tougher core of about HRC 30–45. The hard case resists wear while the softer core absorbs shock loads.

    Choose 40Cr for grinding media and parts that wear down over time; choose SAE 8620 for parts exposed to impact, such as valves and transmission components.

  • Q What are alloy steel balls?

    A
    Alloy steel balls are steel balls made from low- or medium-carbon steels with added chromium, nickel or other alloying elements. These elements let the ball be through-hardened or case-hardened, giving higher hardness, wear resistance and impact toughness than plain carbon steel balls. RISHENG produces alloy steel balls in 40Cr, SAE 8620 and CG08.

     

Request a Quote for Carbon Steel Balls

Send RISHENG your material grade, ball diameter, required quantity and application. Tell us whether you need case-hardened or soft balls, and include the hardness, dimensional tolerance and any case-depth requirement.

For repeat orders, include your part number or previous specification. Packaging, inspection documents and sample requirements can be reviewed with your enquiry.
Contact us
Your drawings and data are kept confidential.

PRODUCTS

QUICK LINKS

CONTACT US

  info@rsbearingball.com
       sales@rsbearingball.com
  +852 6825 8658
    Panjia Town, Summer Villa Village ,Wujin District, Changzhou City, China
COPYRIGHT © 2025  CHANGZHOU RISHENG STEEL BALL CO., LTD.   ALL RIGHTS RESERVED.