Comparision of δ ferrite content measurement methods in austenitic stainless steel weld

The δ ferrite content (mass fraction) of 308 austenitic stainless steel weld was detected by metallographic method, chemical method and magnetic method. The results show that the content of δ ferrite measured under 500 times microscope was 7.6% by using the grid number point method, grid truncation method and eight line method in metallographic method, which was more credible. When the Schaeffler diagram method in the chemical method was adopted, the measured δ ferrite content was about 8.5%, which was close to the measurement results of the metallographic method. The δ ferrite content measured by magnetic method was the lowest, only 3.4%. The three measurement methods had their own advantages and disadvantages, which can be selected according to different situations in practice.