The allowable stress limit of low carbon steel is usually between 150 MPa and 200 MPa.
This range is determined based on the strength, stiffness and service conditions of low carbon steel to ensure safety and stability in actual engineering applications.
The allowable bending stress of carbon steel refers to the ability of carbon steel materials to resist bending damage under specific conditions. It reflects the mechanical properties and structural safety of the material during bending. The value of the allowable bending stress is affected by many factors, including material composition, manufacturing process, ambient temperature, etc.
Calculation method
The following main factors need to be considered when calculating the allowable bending stress of carbon steel:
First, explain the concept of compressive strength. Compressive strength, code σbc, refers to the ultimate strength of the material under external pressure. Metal materials are divided into plastic materials (such as low carbon steel) and brittle materials (such as cast iron). When plastic materials are compressed and deformed, they will only become flatter and flatter. They have no compressive strength, but only allowable extrusion stress. However, brittle materials will be crushed or cracked when compressed. They have compressive strength, and their compressive strength is higher than their tensile strength.
The allowable compressive stress of Q235B steel can only be calculated by the allowable extrusion stress:
[β]=（1.5-2.5）*[σ]—-Applicable to plastic materials
[β]=（0.9-1.5）*[σ]—-Applicable to brittle materials
[σ] is the allowable stress of the material.
Q235 mechanical properties:
Elastic modulus (E/Gpa): 200~210
Poisson’s ratio (ν): 0.25~0.33
Tensile strength (σb/MPa): 375-500
Elongation (δ5/%):
≥26 (a≤16mm)
≥25 (a>16-40mm)
≥24 (a>40-60mm)
≥23 (a>60-100mm)
≥22 (a>100-150mm)
≥21 (a>150mm)
Where a is the thickness or diameter of the steel.
Elastic modulus: This is a measure of the material’s ability to resist elastic deformation.
Yield strength: This is the stress at which the material begins to deform plastically when the force reaches a certain critical value.
Bending radius: The smaller the bending radius, the greater the required bending stress.
Through professional mechanical calculation formulas, the allowable bending stress values under different conditions can be obtained. These calculation results provide an important basis for sheet metal processing design and help to select appropriate materials and sheet metal design solutions.
Finally, we can quickly know the corresponding stress upper limit based on the carbon steel grade, for example: What is the allowable stress of general carbon steel materials?
Taking Q235 as an example, the yield stress of Q235 is 235MPa, which is the origin of the Q235 grade.
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