Small collection of steel knowledge

Steel is an essential material in our lives. How much do you know about steel? What is the yield point, what is the yield strength, do you know all this knowledge? The relevant knowledge is introduced below.

1. Steel yield point (s)

When the steel or sample is stretched, when the stress exceeds the elastic limit, even if the stress no longer increases, the steel or sample still continues to undergo significant plastic deformation. This phenomenon is called yielding, and the minimum yielding phenomenon occurs The stress value is the yield point.

Suppose Ps is the external force at the yield point s, Fo is the cross-sectional area of u200bu200bthe sample, then the yield point s u003d Ps/Fo (MPa), MPa is called MPa equal to N (Newton)/mm2, (MPau003d106Pa, Pa: Pascal u003d N/m2).

2. Steel yield strength (0.2)

The yield point of some metal materials is extremely inconspicuous and it is difficult to measure. Therefore, in order to measure the yield characteristics of the material, it is stipulated that the permanent residual plastic deformation is equal to a certain value (usually 0.2% of the original length). It is called conditional yield strength or yield strength 0.2 for short. (Guide: Measures to prevent locking of stainless steel fasteners)

3. Steel tensile strength (b)

The maximum stress value reached by the material in the process of stretching from the beginning to the occurrence of fracture. It indicates the ability of the steel to resist fracture and the corresponding tensile strength, as well as the compressive strength and flexural strength.

Suppose Pb is the maximum tensile force reached before the material is broken, and Fo is the cross-sectional area of u200bu200bthe sample, then the tensile strength b u003d Pb/Fo (MPa).

4. Steel elongation (s)

After the material is broken, the percentage of the plastic elongation length to the original sample length is called the elongation or elongation.

5. Steel yield ratio (s/b)

The ratio of the yield point (yield strength) of the steel to the tensile strength is called the yield ratio. The larger the yield ratio, the higher the reliability of structural parts. Generally, the yield ratio of carbon steel is 0.6-0.65, which is lower Alloy structural steel is 0.65-0.75 alloy structural steel is 0.84-0.86.

6. Steel hardness

Hardness indicates the ability of a material to resist hard objects pressed into its surface. It is one of the important performance indicators of metal materials. Generally, the higher the hardness, the better the wear resistance. Commonly used hardness indicators include Brinell hardness, Rockwell hardness and Vickers hardness .

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