Comparison of Hot Extrusion and Hot Piercing Processes for Manufacturing Stainless Steel Hot Finished Pipes/Tubes

Abstract

In this work, a comparison study has been performed on the two hot finished manufacturing processes i.e. hot extrusion and hot piercing which are used for manufacturing stainless steel hot finished pipes/tubes. Study is based on different parameters which include raw material, temperature, extrusion ratios, manufacturing process, compressive stresses, shear stresses, friction forces, tooling, etc. The aim of the study is to determine the qualitative difference in the output product which is manufactured through these two processes for hot finished pipes manufactured in austenitic, duplex, super-duplex stainless steels and nickel alloys. The study includes the testing of the hot finished product with non-destructive testing techniques of water immersion ultrasonic testing, Inside Diameter eddy current testing and dye penetrant testing and destructive testing techniques of mechanical testing, microstructure analysis and corrosion testing methods for confirming the qualitative difference in the outputs of both the processes. The products manufactured by hot extrusion are much more superior in terms of defects observed on the inside of the hot finished pipe apart from material soundness, metallurgy and corrosion properties.