316L stainless steel welded pipe is a basic pipe, so it also has a lot of hard necessary indicators, including many aspects, the next we want to talk about the hardness index of 16L stainless steel welded pipe. According to the test method and the scope of application, the hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. For pipes, there are generally three kinds of Brinell, Rockwell and Vickers hardness.
1. Brinell hardness (HB with a certain diameter of steel ball or cemented carbide ball, with the delimited test force (F) pressed into the surface of the sample, after delimiting the holding time to remove the test force, measure the indentation diameter (L) on the surface of the specimen Brinell hardness value is the quotient obtained by dividing the test force by the indentation spherical surface area. Expressed in HBS (steel ball), the unit is N/mm2 (MPa, its calculation formula is: F-the test force pressed into the surface of the 316L stainless steel welded pipe sample, N, D--the diameter of the steel ball for testing, mmd--uniform diameter of the indentation, mm. The determination of Brinell hardness is more correct and reliable, but generally HBS is only suitable for metal materials below 450N/mm2 (MPa), and is not suitable for harder steel or thinner 316L stainless steel welded pipe. In the scale of 316L stainless steel welded pipe, Brinell hardness is the most widely used, often with the indentation diameter d to indicate the hardness of the material, which is both intuitive and convenient.
Example: 120HBS10/1000130 means that the Brinell hardness value measured by using a 10mm diameter steel ball under the action of 1000Kgf (9.807KN) test force of 1000Kgf (9.807KN) is maintained for 30s (seconds) to be 120N/mm2 (MPa).
2. Rockwell hardness (HK) The Rockwell hardness test is the same as the Brinell hardness test, which is an indentation test method. The difference is that it measures the depth of the indentation, that is, under the successive action of the initial test force (Fo) and the total test force (F), the indenter (gold steel mill cone or steel ball) is pressed into the surface of the specimen, and after the holding time is delimited, the main test force is removed, and the hardness value is calculated by the measured residual indentation depth increment (e). Its value is an unnamed number, represented by the symbol HR, and the rulers used are A, B, C, D, E, F, G, H, K and other 9 scales. Among them, the ruler commonly used for the hardness test of 316L stainless steel welded pipe is generally A, B, C, that is, HRA, HRB, HRC. The hardness value is calculated by the following formula: when tested with A and C scales, HR=100-e When tested with B scales, HR=130-e in e--residual indentation depth increment, which is shown in the delineated unit 0.002mm, that is, when the axial displacement of the indenter is one unit (0.002mm), it is commensurate with the change of Rockwell hardness by a number.
