Session: 03-06-01 Advances in Materials and Manufacturing Technology

Paper Number: 79080

79080 - Finite Element Modeling of the Effect of Different Post-Weld Heat Treatment on Strength of Welded AISI 4130 Steel Pipe 

AISI 4130 steel is a low alloy steel strength and is thus a populat choice for fabrication of the drilling fluid pipes. One of the drawbacks of this low alloy steel is that it can form martensite at relativly low cooling rates during welding. That is why the welds in this steel require post weld heat treatment (PWHT) to temper the martensite in the heat affected zone (HAZ). While tempering martensite in HAZ, the heat treatment might also lead to weakening of the base material near the weld in case when heat treatment temperature is too high. In 2014 the PWHT prosedure for welded pipes in the ASME Code (ASME B31.3) has been changed and the maximum allowed PWHT reduced. Hence, the old welds have been heat treated at the temperatures that are too high by the new standard. 

The presented article Investigates the effect of PWHT at the strength of the AISI 4130 steel and models the pipe collapse by finite element methods to investigate the possible effects of the old heat treatment procedure on the pipe strength. First the effect of the old PWHT on the base material strength is investigated by tensile tests of samples under different heat treatments. Then, the rupture of the pipe is modeled by explicit finite element method to evaluate what effect anticipated material weakening has with  regard to the pipe integrity.

Presenting Author: Even Englund LEIRVIK AS

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