Abstract: Ferrite content is very important as its content will influence the corrosion resistance, toughness, strength and other property of stainless steel weld. There are a lot of methods can determinate ferrite content, the diagram and the magnetic ferrite content testing methods are usually used. The latest progress of these two methods is reviewed. Samples preparation and measurement among several laboratories, surface process and so on all influence the precision of ferrite content determination. When ferrite content is less than 5 ferrite number(FN), the variation of prediction according to the diagram testing methods is ±60% of average value. However, the experience data shows that the variation is about ±30% of average value, when FN is at FN values of 15 to 35. As a relative more precise measured method, magnetic method has successfully reduced the variation to ±20% of average value, which is less than that of diagram method. The new prediction methods, considering the effect of element interactions, cooling rate on the ferrite content, promoted its predicted accuracy. “target scope” of FN is suggested to deal with the controversy between welding material designer and user on test result due to the inevitable variation in ferrite content testing.

Key words: stainless steel weld metal;ferrite content;ferrite number(FN);variation