Chrome Moly DIN 1.6522 Alloy Steel Bars

Product Description

DIN 1.6522 (chemical designation 20MnNiCrMo3-2 or 20NiCrMo2) is a specialized, low-carbon alloy steel. While it contains chromium and molybdenum, it is technically an advanced Nickel-Chromium-Molybdenum (Ni-Cr-Mo) triple-alloy steel closely related to the popular 1.6523 (AISI 8620) grade.

Unlike high-tensile through-hardening bars, 1.6522 is primarily engineered as a case-hardening (carburizing) steel or a high-toughness steel for extreme-duty fatigue applications, such as welded round link chains and high-wear machinery components.

Global Equivalents

Because 1.6522 sits right next to the classic "8620 family" on the metallurgy spectrum, it cross-references closely with:

• USA (AISI/SAE): AISI 8620 / 8620H (Very close variant)

• Germany (DIN / WNr): 20MnNiCrMo3-2 / 20NiCrMo2 / 1.6522

• Europe (EN): 20NiCrMo2-2 (1.6523) or 20NiCrMo2F

• France (AFNOR): 20NCD2

• Japan (JIS): SNCM220

Chemical Composition (Typical %)

The lower carbon content (around 0.20%) is intentional; it keeps the core of the bar highly ductile and weldable, while the Cr, Ni, and Mo elements maximize hardenability during case carburizing.

Core Mechanical Properties (Typical Heat-Treated State)

When case-hardened (carburized, quenched, and tempered), a 1.6522 alloy bar achieves a dual-nature profile: a hard, wear-resistant outer skin with an incredibly shock-absorbing core.

• Core Tensile Strength: 660 – 1160 MPa (highly dependent on section size and heat treatment)

• Core Yield Point: ≥ 470 – 560 MPa

• Elongation ($A_5$): 9% – 12%

• Surface Hardness (Post-Carburization & Temper): Typically 58 – 62 HRC

• Maximum Supplied Brinell Hardness (Soft Annealed): ≤ 210–230 HBW (for optimal machining before hardening)

Distinct Engineering Characteristics

• Superior Weldability: Thanks to its low carbon threshold and optimized chemistry, it can be welded reliably (e.g., forming high-strength heavy chain links) without the intense cracking risks associated with higher-carbon equivalents like 4140 or 4340.

• Controlled Grain Growth: It responds beautifully to fine-grain processing treatments, ensuring that components don't become brittle under heavy, repetitive shock loads.

• Case Depth Uniformity: The trace molybdenum and nickel combination ensures a reliable, predictable depth of hardness (case depth) when gas- or vacuum-carburized.

Typical Applications

DIN 1.6522 round and flat bars are highly sought after for components subjected to intense surface friction, high pressures, and dynamic shock:

• Mining & Lifting: Heavy-duty welded round link hoisting and conveyor chains.

• Automotive & Heavy Equipment: High-speed drive pinions, planetary gear wheels, spline shafts, and universal joints.

• Machinery Spares: High-wear pins, bushings, cam rollers, and heavy-duty clamping hardware that requires a glass-hard surface but a shatter-proof center.