PN 18HGT Alloy Steel Bar 18HGT Round Bars 18HGT Rods

Product Description

The 18HGT grade is a high-quality, chromium-manganese-titanium (Cr-Mn-Ti) alloy steel specified primarily under the Polish standard PN-H-84030 (and heavily mirroring the Soviet/GOST standard system).

It is specifically engineered as a carburizing (case-hardening) steel. The targeted addition of titanium ($Ti$) acts as a grain-refining agent, ensuring that the steel retains an exceptionally fine microstructure even during long exposure to high carburizing temperatures. This translates to an incredibly hard, wear-resistant outer shell over a tough, shock-absorbing core.

🛠️ Chemical Composition (%)

The precise synchronization of chromium and manganese boosts the core strength and hardenability, while titanium prevents grain growth.

🔄 International Equivalents

18HGT belongs to a specialized class of Eastern European case-hardening alloys, aligning closely with the following standards:

• Russia / CIS (GOST): 18KhGT / 18ХГТ (Direct equivalent)

• China (GB): 20CrMnTi (Very close match, slightly higher carbon allowance)

• Germany / Europe (DIN EN): 20MnCr5 / 1.7147 or 16MnCr5 (Functional substitutes, though they lack the dedicated Titanium grain refinement)

• USA (AISI/SAE): 5120 or 4118 (Approximate functional alternatives for case-hardening applications)

📈 Mechanical Properties (Typical Heat-Treated State)

After undergoing standard heat treatment—consisting of carburizing, quenching, and low-temperature tempering—18HGT exhibits high core strength alongside its hardened surface.

• Tensile Strength ($R_m$):$\ge 1180\text{ MPa}$

• Yield Strength ($R_e$):$\ge 830\text{ MPa}$

• Elongation ($A_5$):$\ge 10\%$

• Reduction of Area ($Z$):$\ge 40\%$

• Impact Energy ($KV$):$\ge 49\text{ J}$

• Typical Surface Hardness (Post-Carburization):$58 - 62\text{ HRC}$

⚙️ Key Technical Features

• Grain Growth Resistance: The micro-alloyed titanium forms stable titanium carbides that pin grain boundaries, preventing embrittlement during prolonged high-temperature carburizing cycles.

• Superb Core Toughness: Even when the exterior is hardened to resist severe abrasion, the core remains highly ductile to absorb sudden dynamic impacts and torsional shocks.

• Good Machinability: In its annealed or normalized delivery state, 18HGT machines cleanly, making it ideal for high-speed gear cutting and spline broaching.

🚀 Typical Applications

18HGT round bars and rods are heavily favored in heavy machinery, automotive transmissions, and powertrain manufacturing:

• Gears & Pinions: High-load transmission gears, bevel gears, spur gears, and starter ring gears.

• Splined Shafts & Axles: Heavy-duty drive shafts, input shafts, and gearbox countershafts subjected to high torque.

• Pistons & Bushings: Kingpins, piston pins, universal joint journals, and cam tracks requiring a highly wear-resistant armor skin.

Available Supply Forms

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

• Delivery Condition: Most frequently supplied in the annealed ($+A$) or normalized ($+N$) state to allow end-users to perform final machining before case hardening.