The ability of a metal material to resist surface indentation by hard objects is called hardness depending on the test method and scope of application. Hardness can be divided into Vickers hardness, Shore hardness, Brinell hardness, Rockwell hardness, microhardness, and high-temperature Hardness, etc. For anti-corrosion spiral steel pipes, three commonly used hardnesses are Rockwell, Brinell, and Vickers hardness.
A. Rockwell hardness (HK) The Rockwell hardness test, like the Brinell hardness test, is an indentation test method. The difference is that it measures the depth of the indentation. That is, under the sequential action of the initial test force (Fo) and the total test force (F), the indenter (cone or steel ball of the steel mill) is pressed into the surface of the sample. After the specified holding time, the main force is removed. Test force, use the measured residual indentation depth increment (e) to calculate the hardness value.
B. Brinell hardness (HB) Use a steel ball or cemented carbide ball of a certain diameter to press into the sample surface with the specified test force (F). After the specified holding time, remove the test force and measure the indentation diameter on the sample surface. (L) Brinell hardness value is the quotient obtained by dividing the test force by the indentation spherical surface area.
C. Vickers hardness (HV) The Vickers hardness test is also an indentation test method. It presses a square pyramidal diamond indenter with an included angle of 1360 degrees into the test surface at a selected test force (F). After the specified holding time, remove the test force and measure the length of the two diagonals of the indentation. Vickers hardness value is the quotient obtained by dividing the test force by the indentation surface area. Its calculation formula is: HV–Vickers hardness symbol, N/mm2 (MPa); F–test force, N; d–pressure The arithmetic mean of the two diagonals of the trace, mm. The test force F used in Vickers hardness is 5 (49.03), 10 (98.07), 20 (196.1), 30 (294.2), 50 (490.3), 100 (980.7) Kgf (N) and other six levels. The hardness value can be measured The range is 5~1000HV.
Post time: Dec-27-2023