Water-Quenched Spring Steels
C55S – 1.1204 / Ck55 / C50RR / CS50
C55S – 1.1204 steel grade belongs to the group of medium-carbon structural steels and is widely used in applications that require high strength and hardness. Although it is known under different designations in various countries, its fundamental characteristics remain very similar. For example, this steel is referred to as Ck55 in Germany, C55S in certain European standards, C50RR in France, and CS50 in the United Kingdom. These alternative designations allow the steel to be widely recognized and used in international engineering and manufacturing industries.
This steel grade typically contains approximately 0.50% – 0.55% carbon. Due to its medium carbon content, it offers significantly higher strength and hardness compared to low-carbon steels. In addition, its mechanical properties can be greatly improved through appropriate heat treatment processes. By applying hardening and tempering, both the strength and wear resistance of the material can be enhanced. For this reason, it is frequently used in moving machine components and load-bearing elements.
C55S steel provides a well-balanced structure. When hardened, it can achieve high strength, while tempering reduces brittleness and improves toughness. These characteristics allow engineers to optimize the material for different applications. Its machinability is moderate, and it is generally processed using operations such as turning, milling, or grinding.
One of the key advantages of this steel grade is its good resistance to wear. As a result, it can be safely used in components exposed to continuous friction or load transmission. Especially in machine manufacturing and the automotive industry, it provides durable and long-lasting solutions.
C55S – 1.1204 steel stands out as a reliable and cost-effective material for applications requiring strength and performance. Its ability to achieve high mechanical properties through proper heat treatment has made it an important engineering material in modern industry.
Main Application Areas
- Production of shafts and machine spindles in machinery manufacturing
- Gears, pinions, and transmission components
- Springs and elastic machine elements
- Mechanical components exposed to wear
- Durable parts used in agricultural machinery
- Various mechanical components in the automotive industry
- Tooling and die components
- Load-bearing structural elements
- Machine parts designed for heat treatment hardening
Thanks to these characteristics, C55S – 1.1204 and equivalent steel grades are widely preferred engineering materials in many industrial applications that require durability, strength, and reliability.
General Identity
C55S – 1.1204
| Grade |
C55S |
| Number |
1,1204 |
| Classification |
Steel |
Equivalent Grades
C55S – 1.1204
| Germany, DIN |
1.1203 Ck55 |
| France, AFNOR |
C50RR |
| England, BS |
CS50 |
Standards
C55S – 1.1204
| Standard 1 |
EN 10132-4: 2000 |
Chemical Composition
C55S – 1.1204
| C |
0.52 – 0.60 |
| Si |
0.15 – 0:35 |
| Mn |
0.60 – 0.90 |
| Ni |
max 0.40 |
| P |
max 0.025 |
| S |
max 0.025 |
| Cr |
max 0.040 |
| Mo |
max 0.10 |
Mechanical Properties
C55S – 1.1204
| Nominal thickness (mm) |
0.3 – 3 |
| Rm – Tensile strength (MPa) (+A) |
600 |
| —– |
—– |
| Nominal thickness (mm) |
0.3 – 3 |
| Rm – Tensile strength (MPa) (+CR) |
1070 |
| —– |
—– |
| Nominal thickness (mm) |
0.3 – 3 |
| Rm – Tensile strength (MPa) (+QT) |
1100 – 1700 |
| —– |
—– |
| Nominal thickness(mm) |
0.3 – 3 |
| Rp0.2 0.2% proof strength (MPa) (+A) |
480 |
| —– |
—– |
| Nominal thickness (mm) |
0.3 – 3 |
| A – Min. elongation Lo = 80 mm (%) (+A) |
17 |
| Vickers hardness ( HV): (+A) |
185 |
| Vickers hardness ( HV): (+CR) |
300 |
| Vickers hardness ( HV): (+QT) |
340 – 520 |
