Unalloyed quenched and tempered steel with medium carbon content

Steel grade 1.0503 (C45, ČSN 12050) is the most commonly used unalloyed quenched and tempered steel with medium carbon content. It is a versatile material suitable for heat treatment – hardening and tempering. After quenching and tempering, it achieves good strength, hardness, and toughness, making it ideal for a wide range of engineering components.

Properties of steel 1.0503 (C45)

🔩 Good strength after quenching and tempering
High strength can be achieved through hardening followed by tempering (Rm approx. 600–800 MPa).

🔧 Very good machinability
Easy to machine by milling, turning, and drilling. Suitable for precise machine parts.

⚙️ Possibility of local hardening
Allows induction surface hardening up to 52–58 HRC, while the core remains tough.

🔥 Heat-treatable steel
Unlike structural steels such as S355, this steel is specifically intended for quenching and tempering.

🛠️ Moderate toughness
When properly treated, it offers a good balance of strength and toughness.

Chemical composition 1.0503 (C45)

Element	Content (%)
C	0.42 – 0.50
Mn	0.50 – 0.80
Si	0.10 – 0.40
P	≤ 0.040
S	≤ 0.040

Typical applications of steel 1.0503

🛠️ Mechanical engineering
shafts, pins, tie rods

holders, brackets

pistons and spindles

⚙️ Production of medium-stressed parts
gears

bushings, sleeves

latches, mechanism pins

🔩 Hydraulic and pneumatic systems
piston rods

cylindrical components

🚜 Agricultural machinery
basic rotating parts

medium-stressed components

Heat treatment (guideline values)

Process	Temperature	Note
Hardening	820 – 860 °C	quenching in water or oil
Tempering	540 – 680 °C	depending on the required strength
Quenching and tempering	–	هدف: strength + toughness
Induction hardening	800 – 860 °C	surface hardness 52–58 HRC

Mechanical properties (after treatment)

Tensile strength Rm: 600–800 MPa

Core hardness: approx. 170–220 HB

Surface hardness after induction hardening: 52–58 HRC

Elongation A: 14–17%