Carbidic Ductile Iron

[garydavidlarson]

What is the best test to detect low and medium level carbides in ductile iron?

 

[MOB1]

Can be carried out non destructively by an ultrasonic technique (from old BCIRA data - see Castings Technology International web site).
The other method is by micro examination of representative samples.

 

[garydavidlarson]

Ultrasonic testing can detect carbides in certain situations. If the part is partially carbidic with some nodularity the two offset each other and you get an acceptable velocity. I have done this many times. I am a non-destructive testing ASNT Level III. The second detection method of doing a micro is not really what I was after. I need to detect it under test without destroying the part. We are doing some eddy current testing for carbides but I am not totally satisfied with the results. Thanks for the reply.
Gary Larson

 

[TVP]

I consulted ASM HANDBOOK Volume 17 Nondestructive Evaluation and Quality Control and did not find anything other than UT and Eddy Current Testing. There are some variation of ECT that use multiple probes which may be an improvement over your existing method. Good luck.

 

[Mike450]

simple checking for carbides non destructively is not easy as you already know. A very crude segregation technique is to use a file either on the supect area, or where you expect the carbides - edges, corners, thin section or a critical area. Does not give quantitative result but can be a go-no go filter.