In the world of steel strip manufacturing, two mechanical properties are often discussed together — hardness et tensile strength. These characteristics define how steel behaves under force and determine its suitability for applications like ressorts, blades, saws, and precision tools. Understanding their relationship helps engineers and buyers choose the right steel for their needs.
1. What Is Hardness in Steel Strips?
Hardness refers to a material’s ability to resist deformation — such as indentation, scratching, or wear.
In steel strips, hardness is usually measured using the Rockwell (HR), Vickers (HV), or Brinell (HB) scales.
A harder steel strip generally means:
- Better wear resistance
- Higher surface durability
- Less deformation under stress
However, excessive hardness can reduce ductility, making the steel more brittle if not properly tempered.
2. What Is Tensile Strength?
Tensile strength measures the maximum stress a steel strip can withstand before it breaks when stretched. It reflects the internal bonding force between atoms and is usually expressed in MPa (megapascals).
Tensile strength indicates:
- The load a steel can bear in tension
- Its resistance to cracking or rupture
- Its overall toughness and flexibility
3. The Connection Between Hardness and Tensile Strength
In general, hardness and tensile strength increase together.
This relationship exists because both properties are influenced by the steel’s microstructure — particularly the arrangement and size of carbides, martensite, or pearlite formed during traitement thermique.
Typical correlation:
- For carbon and alloy steels, higher hardness usually means higher tensile strength.
- For stainless steels, the relationship is similar but depends more on alloy composition (Cr, Ni, Mo, etc.).
For example:
- A quenched and tempered 65Mn steel strip may reach 48–52 HRC hardness et tensile strength up to 1800 MPa.
- A cold-rolled, annealed CK75 strip might have 30–35 HRC et tensile strength around 950–1100 MPa.
4. The Role of Heat Treatment
Heat treatment directly determines both hardness and tensile strength.
Processes like recuit, trempe, et tempering modify the steel’s internal structure:
| Process | Effect on Hardness | Effect on Tensile Strength | Typical Use |
|---|---|---|---|
| Annealing | Decreases | Moderate | Improves ductility, used for stamping or forming |
| Quenching | Increases | Increases | Creates hard martensitic structure |
| Tempering | Slightly decreases | Improves toughness | Reduces brittleness after quenching |
At Jiaxiao MTC, each steel strip is precisely heat-treated to achieve the optimal balance between hardness and strength for different industrial needs — from knife blades to automotive springs.
5. Why the Balance Matters
Too much hardness leads to brittleness, while too low tensile strength causes deformation.
Therefore, choosing the right steel grade and heat treatment is essential for product performance and longevity.
For example:
- Hardened and tempered SK5 strips are ideal for cutting tools.
- Annealed 301 stainless strips offer excellent forming ability for flexible components.
Conclusion
Hardness and tensile strength are two sides of the same coin in steel performance.
By understanding how these properties interact — and controlling them through heat treatment — manufacturers can produce high-performance steel strips tailored for each application.
At Jiaxiao MTC, we specialize in high-carbon, alloy, et bandes d'acier inoxydable, offering customized hardness and tensile strength levels to meet the precise requirements of our clients worldwide.
