Crack Testing of Raw Materials - Steel

[Andrews]

What is the most relaible and cost effective method of crack testing in Raw materials (Steel)? Our Raw material supplier is using Magnaflux testing for Raw material but he is not able to assure us 100% crack free material. What is the best type of control that will assure us 100% crack free material?

 

[Geoff Cotton]

Are we talking about rod stock, wire, or a casting etc..?

 

[SteelMaiden]

Re: crack testing

Andrews said:

What is the best type of control that will assure us 100% crack free material?

Buy turned, ground and polished stock?

Andrews, what shapes are you purchasing? Are you buying rod or bar stock, or beams, plates or what? There is no such thing as "perfect" surface on steel, unless it has been "surfaced" by some sort of grinding process. The standards allow for a certain depth of crack dependent upon the diameter/thickness of the material. That being said, depending on what shapes you are talking, there is eddy-current, dye-penetrant, ultrasonic and others to assess for cracks. I have found, that nothing is 100% fail-safe 100% of the time, even dye-penetrant will miss some cracks, if they have welded shut during hot-rolling.

I'm sure this wasn't the answer you were hoping for, but without a little more information, it is difficult to recommend anything specific. Good luck!

 

[Sam]

X-ray methods would be my choice where internal crack detection is a concern.

 

[Andrews]

Thanks everybody for the response.

The raw material used by us is bright bars of sizes from 6mm to 40 mm HEX / Diameter.

Is X-Ray testing a cost effective method of testing raw material for crack?

Can Crack be avoided at the source itself? If so, what method should be used?

 

[Sam]

You would have to perform your own cost analysis to determine if the X-ray method is cost effective to you.
If you want to limit the possibility of cracks at the source discuss it with your supplier. He may have alternative methods of providing what you want.
As Steelmaiden said, nothing is 100%fail safe, 100% of the time.

 

[atibha]

Re: crack testing

sir i am also trubling with this situation so plz suggest me how to find out deep crack in raw material bar .
because i have got one complain from customer side he told that deep crack observed and its is raw material crack.
so plz suggest how to find out deep crack in Raw Material

 

[atibha]

Re: crack testing

sir can u tell how to distinguished crack of forging ,raw material and heat treatment by eyes.how to look like crak of forging ,raw material .and heat treatment

 

[Jen Kirley]

Re: crack testing

sir i am also trubling with this situation so plz suggest me how to find out deep crack in raw material bar .
because i have got one complain from customer side he told that deep crack observed and its is raw material crack.
so plz suggest how to find out deep crack in Raw Material

Good day atibha and welcome to the Cove.

In my experience we located deep, under-surface cracks with magnetic particle testing for ferrous materials, and ultrasonic testing for ferrous or non-ferrous metals. We used an oscillisope display, but more modern equipment may provide easier methods for "reading" the discontinuities.

For ultrasonic testing the surface should be smooth as the transducer should be able to travel without interference that might invalidate the signal.

I hope this helps!

 

[ndtqc]

Ultrasonic inspection is by far and away the best and most cost efficient method for detection. UT inspection is capable of setting up on reference flaws (EDM notches for both circumferential and axial scanning for surface flaws) and (flat bottom holes or side drilled holes for sub-surface flaws). Often times depending on who you are getting your steel from they will have performed some type of NDT. Magnaflux testing (actually MT) as Magnaflux is a manufacturer of MT supplies and equipment, is only good for surface flaws open to the surface or slightly subsurface. Depending on the volume of material you need to inspect I would suggest using a third-party NDT service provider for this inspection. You would need to access what you were looking for specifically (surface flaws/subsurface flaws/both) and they should be able to give you guidance on a specification. I don't recall off hand but possible AMS2154 or ASTM A388. A general inspection parameter (AMS2154 Class A w /shearwave) for bar stock would be UT inspection using a 3/64 in FBH and a 0.010 notch for surface defects. Just my opinion.