Mechanical property testing of steel bars, steel plates, and steel products

The mechanical property testing of steel and steel products is to determine the mechanical properties of steel by applying a certain external force or energy to a sample of steel. In testing, scientific evaluation of various materials can help enterprises choose new processes and materials. Material testing can identify the applicability, feasibility, effectiveness, and other aspects of materials, which is of great help in improving product quality.

What are the methods and items for testing the mechanical properties of steel bars, steel plates, and steel products? What equipment is needed for inspection?

1. Testing of yield strength of steel

The stress at which the elastic deformation point transitions to plastic deformation is called the yield strength, also known as the yield point. It is divided into upper yield strength and lower yield strength, represented by ReH and ReI respectively, with units of N/mm2 or MPa

Elastic deformation: Under the tension of the tensile machine, the sample is tensioned. At the beginning, the elongation of the sample is proportional to the tension, and when the tension is released, the sample still returns to its original size. This deformation is called elastic deformation.

Plastic deformation: The specimen continues to deform and elongate under increasing tension, but after the external force is released, the specimen no longer returns to its original length, becoming an irreversible permanent deformation. This type of deformation is called plastic deformation.

2. Testing of tensile strength of steel

In the above tensile test, after the sample undergoes plastic deformation, the tensile force continues to increase and the sample is finally pulled apart. At this point, the stress is the tensile strength, represented by the symbol Rm and measured in N/mm2 or MPa.

3. Testing of elongation of steel

After the metal sample is tensioned and broken, the ratio of the length of the extended part to the original gauge length is called elongation, and the symbol for elongation after fracture is A, with the unit being%

4. Shrinkage rate of steel section

The percentage reduction in cross-sectional area at the fracture surface of a metal specimen during tensile fracture. Its representative symbol is Z, and the unit is%.

5. Bending test detection of steel

Check the ability of steel and its products to withstand bending, as different steels have different requirements for the angle and diameter of bending.

For the above 5 performance tests, it can be fully measured using a Liangong hydraulic universal testing machine or an electronic universal testing machine with corresponding fixtures, and the accuracy level is as high as 0.5, which is better than most products in the same industry, and the performance is stable.

6. Impact toughness of steel

The work consumed per unit area at the groove of a sample with a certain size and groove under the required temperature conditions when it is fractured by an impact load on a testing machine. The representative symbol is ak, and the unit is J/cm2

The performance testing of this impact toughness can rely on a joint impact testing machine, equipped with different high and low temperature instruments according to temperature requirements.

7. Hardness of steel

The ability of metal materials to resist being pressed into their surface by harder objects such as hardened steel balls, diamond cones, etc. The inspection methods include Brinell hardness (HB), Rockwell hardness (HR), Vickers hardness (HV), etc. The corresponding hardness can be measured using Brinell hardness tester, Vickers hardness tester, etc.

At present, there are many brands and types of testing machines on the market, and some customers buy whatever is cheaper in order to save money. This method is not advisable. When users choose devices, they must be cautious and pay attention to brand and manufacturer comparisons. Because some companies do not have direct production capacity, product quality cannot be guaranteed, let alone service. So when choosing, it is necessary to choose a testing machine from a legitimate manufacturer with production capacity and advanced technology. Avoid purchasing equipment that cannot meet usage needs or experiencing continuous problems during use.