GOST 18KHG Alloy Steel Bar 18KHG Round Bars 18KHG Rods

Product Description

The 18KhG (alternatively transliterated from Cyrillic 18ХГ as 18KHG or 18HG) is a high-quality, chromium-manganese alloy structural steel specified under the Interstate standard GOST 4543.

It is engineered primarily as a case-hardening (carburizing) grade. With its balanced chromium and manganese contents, it offers strong core hardenability and high fatigue limits. It acts as the direct base version of the titanium-modified 18KhGT grade, providing high surface hardness alongside reliable core ductility after case treatment.

🛠️ Chemical Composition (%)

The deliberate formulation of chromium ($Cr$) and manganese ($Mn$) enhances the steel’s depth of hardening during quenching.

🔄 International Equivalents

18KhG is functionally substituted by widely recognized European and American case-hardening alloy grades:

• Germany / Europe (EN): 16MnCr5 (1.7131) or 20MnCr5 (1.7147)

• USA (AISI/SAE): 5115 or 5120

• China (GB): 15CrMn or 20CrMn

• Japan (JIS): SMnC420 / SMnC420H

• Poland (PN): 15HG / 16HG

📈 Mechanical Properties (Typical Values)

The ultimate mechanical criteria depend heavily on workpiece diameter and the type of tempering utilized post-quench.

Hardened & Low-Temperature Tempered State (Typical for Case-Hardened Skins)

• Tensile Strength ($R_m$): $\ge 880\text{ MPa}$

• Yield Strength ($R_{e}$): $\ge 735\text{ MPa}$

• Elongation ($A_5$): $\ge 10\%$

• Reduction of Area ($Z$): $\ge 40\%$

• Brinell Hardness (Annealed Supply State): $\le 217\text{ HB}$

⚙️ Key Technical Features

• Response to Carburization: Absorbs carbon efficiently along its outer boundary layers when exposed to a carbon-rich atmosphere, reaching a robust outer surface framework while the interior low-carbon core remains flexible.

• Core Fatigue Strength: Highly resilient against intense torsional stresses and repeated shock, protecting high-vibration parts from sudden cleavage failures.

• Machining Properties: Clean chip creation when processed in the conventional normalized or fully annealed condition, reducing tool wear before the component undergoes final case hardening.

🚀 Typical Applications

GOST 18KhG round bars and rod configurations are commonly used in machine construction, vehicle drive trains, and heavy manufacturing:

• Power Transmission: Medium-load transmission gears, planet carrier components, splined input shafts, and synchronizer cones.

• Friction Components: Bushings, high-wear pins, universal joint journals, and camshaft elements.

• Fastener Tooling: Heavy-duty clamping studs, pins, and high-tensile connecting bolts exposed to cyclic physical loading.

Available Supply Forms

• Finishes: Hot-rolled black bar, hot-forged blocks/bars, or centerless turned/ground bright rods.

• Delivery Condition: Uniformly shipped in the annealed ($+A$) or normalized ($+N$) state to allow standard machining operations prior to final heat treating.