Straight welded pipe
Straight seam welded pipe is a steel pipe made of hot-rolled or cold-rolled steel plate or steel strip by coil welding. The pipes obtained by straight seam welding on the welding equipment are called straight seam welded pipe.
The surface quenching and tempering heat treatment of longitudinal welded pipe is usually carried out by induction heating or flame heating. The main technical parameters are surface hardness, local hardness and effective hardened layer depth. Vickers hardness tester, Rockwell or surface Rockwell hardness tester can be used for hardness testing. The selection of test force (scale) is related to the effective hardened layer depth and the surface hardness of longitudinal welded pipe. There are three kinds of durometer involved here.
Vickers hardness tester is an important means to test the surface hardness of heat-treated Hunan longitudinal welded pipe. It can use the test force of 0.5 ~ 100kg to test the surface hardened layer as thin as 0.05mm. Its accuracy is the highest and can distinguish the small difference in the surface hardness of heat-treated workpiece. In addition, the effective hardened layer depth shall also be tested by Vickers hardness tester. Therefore, it is necessary to equip a Vickers hardness tester for units that conduct surface heat treatment or use a large number of surface heat treated Hunan longitudinal welded pipes.
The surface Rockwell hardness tester is also very suitable for testing the hardness of surface quenched workpieces. There are three scales for the surface Rockwell hardness tester. It can test various case hardened Hunan longitudinal welded pipes with an effective hardening depth of more than 0.1mm. Although the accuracy of surface Rockwell hardness tester is not as high as that of Vickers hardness tester, it can meet the requirements as a testing means for quality management and qualification inspection of heat treatment plant. Moreover, it also has the characteristics of simple operation, convenient use, low price, rapid measurement and direct reading of hardness value. The surface Rockwell hardness tester can be used for rapid and nondestructive testing of batches of surface heat treated Hunan longitudinal welded pipes one by one. This is of great significance to Hunan longitudinal welded pipe processing and machinery manufacturing factory.
