Alloy Steel 20MnCr5 Round Bar 20MnCr5 Bars 20MnCr5 Rods

Product Description

20MnCr5 (Material Number: 1.7147) is one of the most widely used chromium-manganese case-hardening steels (carburizing steels) in the global engineering and automotive industries.

Unlike the high-strength through-hardening steels (like 40NiMoCr10-5), 20MnCr5 is specifically engineered to have a relatively low core carbon content ($0.20\%$). This allows the material to retain excellent core toughness and ductility while its surface layer is enriched with carbon during heat treatment, yielding an incredibly hard, wear-resistant outer shell.

Here is a comprehensive breakdown of the technical properties, international standards, and processing specifications for 20MnCr5 alloy bars, round bars, and rods.

⚙️ Chemical Composition (%)

The combination of manganese and chromium gives this grade excellent core strength and hardenability for a case-hardening steel, making it ideal for parts subjected to high loads and severe friction.

* Note: Controlled sulfur variants (e.g., 20MnCrS5, 1.7149) are frequently specified with a sulfur range of 0.020% to 0.040% specifically to enhance machinability on automated CNC lines.

🌍 International Cross-Reference & Equivalents

20MnCr5 is an international standard-bearer, commonly cross-referenced with the following regional designations:

• EN / DIN Standard: 20MnCr5 / 1.7147 (EN 10084)

• SAE / AISI (USA): AISI 5120 (Closest chemical equivalent)

• JIS (Japan): SMnC420 / SMnC420H

• AFNOR (France): 20MC5

• UNI (Italy): 20MnCr5

💪 Mechanical Properties (Typical Core Values after Case Hardening)

After carburizing, quenching, and tempering, the core of a 20MnCr5 component maintains high impact resistance, while the surface achieves extreme wear resistance:

• Core Tensile Strength ($R_m$): $1000 - 1300 \text{ MPa}$ (depending on section thickness)

• Core Yield Strength ($R_e$): $\ge 700 - 800 \text{ MPa}$

• Elongation ($A_5$): $\ge 9\%$

• Typical Surface Hardness: 60–63 HRC (Rockwell C) after direct or secondary hardening and low-temperature tempering.

🛠️ Typical Applications

Because it perfectly balances a high-fatigue, shock-absorbing core with a glass-hard surface, 20MnCr5 round bars and rods are extensively utilized for driving mechanisms and rotating parts:

• Automotive & Powertrain: Transmission gears, synchronizer rings, drive pinions, camshafts, universal joint spiders, and differential gears.

• Heavy Machinery: Main drive shafts, high-load bushings, kingpins, piston pins, and splined shafts.

• Clamping & Mechanical Hardware: Heavy-duty guide rods, collets, double-bolted mechanical clamps, and high-wear indexing pins.

📐 Delivery Conditions & Machining Advice

• Supply Forms: Available as hot-rolled, forged, cold-drawn, or turned bright bars.

• Optimized for Machining (+TH / +FP): To prevent tool tearing and excessive wear during high-speed gear-cutting or turning, 20MnCr5 is frequently ordered in an annealed state tailored to a specific hardness range (typically 156–207 HB), which guarantees an optimal ferrite-pearlite structure.

• Distortion Control: Because components made from 20MnCr5 undergo intense thermal cycles during carburizing (typically at $880^\circ\text{C} - 980^\circ\text{C}$), it is critical to use symmetric machining practices and stress-relieving steps to minimize dimensional distortion during final oil or gas quenching.