ASTM A519 8620 Case Hardening Seamless Tube Supplier USA

What Are ASTM A519 8620 Seamless Steel Tubes?

The AISI 8620 (SAE 8620/UNS G862000) alloy steel was specifically designed so that it could possess high capability to be case hardened by carburization. Under this heat treatment process, the material is heated to a very high temperature in an environment that is rich in carbon, which allows diffusion of carbon to occur in the material surface, making it harder (5862 HRC) but leaving the core material soft yet tough (3036 HRC). The excellent balance of its chemical components, where nickel provides core toughness, chromium improves hardenability, and molybdenum gives it more strength and thermal stability, ensures that it performs efficiently under shock and cyclic loading conditions. This combination makes it extremely useful in gears, camshafts, bushes, and transmission components. Furthermore, it has excellent case depth flexibility with values from 0.5mm to 2.5mm, giving it an upper hand compared to through-hardened materials like the 4140 alloy steel.

Specification Chemical Composition Mechanical Properties

ASTM A519 8620 Specification Overview

The table below summarises the key specification parameters for Grade 8620 seamless mechanical tube.

Parameter	Details
Standard	ASTM A519 / ASME SA519
Grade	8620
ASME Equivalent	ASME SA519 Grade 8620
Material	AISI 8620 / SAE 8620 / UNS G86200
Alloy Type	Nickel-Chromium-Molybdenum (Ni-Cr-Mo) Triple Alloy
Manufacturing Process	Seamless
Outside Diameter (OD)	0.25 inch to 10 inch (6.35 mm to 254 mm)
Wall Thickness (WT)	0.035 inch to 2.00 inch (0.89 mm to 50.80 mm)
Length	Random, mill-cut, or cut-to-length
Surface Finish	Black (as-rolled), bright drawn, turned and polished
End Finish	Plain ends, chamfered, or as specified
Supply Conditions	CDS (Cold Drawn Seamless), HFS (Hot Finished Seamless), Normalised, Q+T

SAE 8620 Chemical Composition (UNS G86200)

Element	Range / Limit	Engineering Note
Carbon (C)	0.18 to 0.23%	Low carbon = better weldability and carburisability
Manganese (Mn)	0.70 to 0.90%	Contributes to hardenability
Silicon (Si)	0.15 to 0.35%	Deoxidation and strength
Nickel (Ni)	0.40 to 0.70%	KEY: Adds toughness and core strength -- differentiator from 4130/4140
Chromium (Cr)	0.40 to 0.60%	Surface hardness contribution
Molybdenum (Mo)	0.15 to 0.25%	Hardenability and toughness at elevated temperatures
Phosphorus (P)	0.035% max	Keep low -- affects toughness
Sulphur (S)	0.040% max	Keep low -- affects ductility

SAE 8620 Mechanical Properties

Condition	Yield Strength	Tensile Strength (UTS)	Elongation %	Hardness
Annealed (CDS)	385 MPa / 56 ksi	530 MPa / 77 ksi	26%	156 HB max
Normalised	440 MPa / 64 ksi	620 MPa / 90 ksi	24%	179 HB max
Carburised + Q+T (Surface)	--	--	--	58 to 62 HRC surface / 30 to 36 HRC core

Comparison Between 8620 vs 4130 Grade

Grade 8620 and Grade 4130 are both Cr-Mo family alloy steels, and procurement teams frequently ask for a direct comparison. The table below answers every meaningful engineering question about the differences. The fundamental distinction is that these two grades serve entirely different design objectives: 8620 is a carburising grade optimised for surface hardening; 4130 is a through-hardening structural grade.

For through-hardened structural tube and hydraulic cylinder applications, see our ASTM A519 4130 Seamless Tube page. For applications requiring higher through-hardness and where case hardening is not required, see our ASTM A519 4140 Seamless Tube page. When case hardening is required, 8620 is the correct selection.

Applications of ASTM A519 8620 Seamless Steel Tubes

Because of their exceptional combination of surface hardness and core toughness, ASTM A519 8620 Ni-Cr-Mo seamless tubes are the material of choice for a wide range of high-performance mechanical components:

• Transmission gears and ring gears (automotive and commercial vehicle)
• Camshafts and crankshaft components (internal combustion engines)
• Rocker arms and valve train components
• King pins and steering knuckles (heavy truck and off-highway equipment)
• Wrist pins and connecting rod bushings
• Chain sprockets and idler gears
• Drive shaft bushings and couplings
• Agricultural equipment shafts and pivot pins
• Mining and construction equipment wear parts
• Hydraulic and pneumatic cylinder components requiring case hardening

For components where case hardening is not the primary requirement and through-hardness or pressure resistance is the design goal, we recommend reviewing our ASTM A519 4140 Seamless Tube as an alternative. For a broader introduction to alloy steel selection, our editorial Guide to Alloy Steel Pipes and our technical article on Types of Alloy Steel Classification provide detailed grade selection guidance.

Supply Conditions and Dimensional Availability for 8620 CDS Tube

For the full range of cold drawn dimensions in our stocking program, see Cold Drawn Seamless Mechanical Tubing.

How to Specify ASTM A519 8620 Seamless Tube

When ordering ASTM A519 8620 seamless tube, the most important details to confirm are the outside diameter, wall thickness, supply condition, required length, and whether the component will be carburised after machining. Buyers usually select CDS tube when the part requires closer dimensional control, a smoother surface, or reduced machining allowance. HFS tube is normally preferred for larger outside diameters, thicker walls, and applications where the tube will be heavily machined before final heat treatment.

For case hardening work, the drawing or purchase specification should also mention the target case depth, surface hardness, core hardness, and any post-carburising quench and temper requirement. Grade 8620 is selected because its nickel, chromium, and molybdenum chemistry allows a very hard wearing surface while keeping a shock-resistant core. This makes it a practical choice for gears, shafts, bushings, couplings, and other moving parts where wear resistance alone is not enough. If your component needs through-hardness instead of a carburised surface, ASTM A519 4130 or ASTM A519 4140 may be a better engineering choice. USA Piping Solution can supply Grade 8620 tube with mill test certification, traceable heat numbers, standard mill lengths, and cut-to-length processing for production or maintenance requirements.

Frequently Asked Questions