Tensile strength and yield strength of steel plate

Steel plate strength reflects its ability to resist deformation or damage when subjected to external forces. It is a core indicator used to evaluate the quality and performance of steel plates. Key strength metrics include tensile strength, yield strength, and impact toughness.

Among the most common steel plate materials are carbon steel and stainless steel, each offering unique advantages depending on application needs.

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Tensile Strength vs. Yield Strength: Key Differences

- Tensile Strength
Refers to the maximum tensile force per unit area that a steel plate can bear during stretching without breaking.
For example, the tensile strength of Q235 steel is typically between 370–500 MPa, meaning each square millimeter can resist up to 500 Newtons of pulling force.

- Yield Strength
Indicates the stress threshold at which the material begins to undergo permanent (plastic) deformation.
For Q235 steel, the yield strength is about 235 MPa—once exceeded, the material deforms irreversibly.

How to Calculate Steel Yield Strength

The formula to calculate yield strength:

σs = F / A

Where:

σs: Yield strength (MPa)

F: Force applied (N)

A: Cross-sectional area (mm²)

In engineering practice, yield strength values are also referenced from material handbooks or standard charts, which vary based on steel grade and composition. The proper material must be selected according to the load conditions and working environment.

Strength Classifications of Steel Plates

Example: S460N steel

Yield strength≥460 MPa

Tensile strength: 540–720 MPa

Known for excellent strength and impact toughness.

Different industries—such as construction, shipbuilding, automotive, and aerospace—require tailored strength, weldability, and toughness depending on the application.

Factors That Affect Steel Strength

Material Composition
The presence and proportion of elements like carbon, manganese, or silicon greatly influence mechanical strength, hardness, and wear resistance.

Heat Treatment
Processes like quenching or tempering can significantly enhance strength, but improper treatment may reduce performance.

Stress State
Yield strength varies depending on the type of force. It is usually highest under uniaxial tension.

Temperature
Low temperatures often reduce ductility and impact resistance, potentially increasing brittleness.

Thickness and Geometry
Thinner plates may show reduced strength due to grain dispersion and stress concentration.

Strength Testing and Real-World Applications

Steel strength is commonly tested using:

Tensile tests→Determine tensile and yield strength.

Impact tests→Assess resistance to sudden force (impact toughness).

Why it matters:
Steel plate strength determines safety, durability, and load-bearing capacity. High-strength steel is essential for:

Bridges and high-rise buildings

Heavy-duty vehicles and railcars

Structural components in marine and energy industries

In short, understanding steel plate strength ensures not only structural integrity, but also efficient material selection for different engineering applications.