Alloy Steel 070M20 Round Bar 070M20 Bars 070M20 Rods

Product Description

070M20 (formerly commonly known as EN3A) is a high-quality, unalloyed medium-carbon steel specification within the British Standard BS 970 system.

Unlike the previous alloy steels you looked at, 070M20 is technically classified as a carbon steel because it does not rely on deliberate additions of alloying elements like chromium, nickel, or molybdenum. Instead, it is an economical, general-purpose engineering steel widely specified for components that require decent structural strength, good machinability, and reliable weldability without the cost premium of full alloys.

Global Cross-Reference & Equivalents

When sourcing or replacing BS 970 070M20 round bars and rods in international markets, you can map them directly to these global equivalent grades:

Chemical Composition (Typical wt.%)

The chemistry of 070M20 is strictly controlled to maintain excellent formability and ensure it doesn't harden excessively during welding.

• Carbon (C): 0.16% – 0.24%

• Manganese (Mn): 0.50% – 0.90%

• Silicon (Si): 0.10% – 0.40%

• Phosphorus (P): $\le$ 0.050%

• Sulfur (S): $\le$ 0.050%

Supply Forms & Mechanical Properties

070M20 round bars are highly versatile and typically supplied in two primary finishes, which fundamentally dictate their mechanical behavior:

1. Delivery Conditions

• As-Rolled / Forged (+AR): Hot-worked bars suitable for subsequent forging, bending, or extensive heavy machining.

• Cold Drawn / Bright Turned (+C): Cold-finished bars that offer tight dimensional tolerances, a smooth scale-free surface, and elevated yield strength due to strain hardening.

2. Standard Mechanical Properties

The values below represent typical limits for standard structural thickness sections (e.g., up to 63mm diameter):

Primary Applications & Processing

Because of its balanced profile, 070M20 is the go-to structural steel for low-stress machinery components, brackets, and frameworks:

• Welded Assemblies: Excellent for structural fabrications, crane components, and frames because it does not require complex pre-heat or post-weld thermal cycles.

• Fasteners & Spindles: Standard choice for low-stress shafts, tie rods, spacer rings, keys, dowels, studs, and low-load threaded fasteners.

• Case Hardening Option: While it isn't an alloy steel like 16MnCr5, 070M20 can be carburized or cyanided if your application requires a thin, wear-resistant skin over a very ductile core.