Alloy Steel 27MnCrB5 Round Bar 27MnCrB5 Bars 27MnCrB5 Rods

Product Description

27MnCrB5 (specifically 27MnCrB5-2, Werkstoffnummer 1.7182) is a European standard (EN ISO 683-2 / EN 10083-3) boron-alloyed, heat-treatable low alloy engineering steel. It is highly valued for its exceptional wear resistance, hardenability, and mechanical strength, making it an excellent material for heavy-duty round bars, rods, and structural components exposed to high stress and abrasive wear.

Technical Specifications & Chemical Composition

The defining characteristic of 27MnCrB5 is the precise addition of Boron (B). Even in minute quantities, boron significantly boosts the steel’s hardenability during quenching without compromising cold formability or machinability in the annealed state. Manganese (Mn) and Chromium (Cr) further enhance depth-hardening and tensile strength.

Chemical Composition (Weight %)

Note: Titanium (Ti) is typically added in small amounts (0.02–0.06%) to fix nitrogen and ensure the boron remains effective.

Mechanical Properties (Quenched & Tempered Condition)

When supplied or heat-treated to the +QT (Quenched and Tempered) condition, 27MnCrB5 exhibits excellent core strength and uniform hardness across varying bar cross-sections.

Typical Properties by Round Bar Diameter ($d$)

• Core Hardness: Achieves a highly resilient core hardness of ~38 HRC (after 80% martensite transformation).

• Density: 7.85 $\text{g/cm}^3$

• Modulus of Elasticity: 210 GPa

Heat Treatment Guidelines

• Forging / Hot Rolling: 1200°C – 850°C

• Normalizing: 860°C – 890°C

• Soft Annealing (+A): 650°C – 700°C (yields a hardness typically $\le$ 250 HBW for optimal machinability)

• Hardening: 840°C – 880°C

• Quenching Medium: Water (recommended for diameters up to 52 mm) or Oil (recommended for diameters up to 43 mm to minimize distortion).

Key Applications of 27MnCrB5 Round Bars & Rods

Because it combines high tensile strength with superb wear performance at a more cost-effective price point than highly alloyed Ni-Cr-Mo steels, 27MnCrB5 round bars are prominently used in:

• Heavy-Duty Fasteners: High-tensile bolts, clamping hardware, and structural studs.

• Agricultural Engineering: Plowshares, harrow discs, and rototiller shafts that undergo continuous abrasion.

• Automotive & Suspension Systems: Axles, crankshafts, steering links, shift forks, and torsion bars.

• Mechanical Components: Drive shafts, sprocket gears, heavy-duty chain wheels, and wear-strips for yellow-goods (dredger buckets, earthmovers).

Supply & Processing Forms

• Round Bars / Rods: Available in hot-rolled (+AR), cold-drawn, or turned finishes.

• Machinability & Weldability: Excellent tool life in the soft-annealed state. Due to the medium carbon content and manganese levels, preheating is advisable if structural welding is required on hardened components to eliminate the risk of cold cracking.