Hardness testing is is it a NDT Test ? 1

[stanislasdz]

May be a basic question but an internal auditor ask us a question: Hardness testing Is it a NDT Test?

I really don't have the good answer

For rough forgings parts I guess it's NDT TEST, for machined parts I guess NO

Any help?

Thanks

 

[MikeHalloran]

If you're only interested in surface hardness, and in a place where the indenter mark won't be an intolerable stress raiser, it's NDT.

If, e.g., you want to measure the depth of case hardening, you have to slice through the part and run a line of hardness tests; definitely DT.



Mike Halloran
Pembroke Pines, FL, USA

 

[SectionIX]

In general, yes it is a NDE method. Depends on the material, application, and HT method.

For instance, an equotip or microdur test on a 516-70 pressure vessel will not cause future usability problems.

A telebrineller test on a thin cast iron motor housing would not...

 

[arunmrao]

Tempted to say it is NDE but with some restrictions/conditions,which can alter the character of testing .

_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year

 

[metengr]

Hardness testing is NOT nondestructive testing by codes/standards definition. It is simply a test method used to compare hardness of materials.

 

[salmon2]

By definition and catogories, it is not NDE that people are usually talking about.

But can a finished part receive a hardness test without affecting its application? Yes or no, depending on size, testing method, where to test, etc.

 

[redpicker]

Every quality system I have been involved with has not considered hardness testing NDT/NDE. While it can share characteristics with NDE/NDT tests, such as it does not damage the part, you cannot verify acceptance without re-testing, etc..., the qualification of personnel and procedures are much more similar to those required for other destructive testing methods and will usually not meet the requirements for qualification of NDE procedures and personnell.

rp

 

[JR97]

I will weigh in with the NOT an NDE side. My conclusion is based on Hardness testing not being recognized in SNT-TC-1A which is fairly universally called out to establish training, experience, and examination requirements for different NDE methods.

JR97

 

[MetalHead83]

Hardness testing is not Necessarily destructive. It really depends on your specific use.

As Metenger said, it is not defined as destructive because it can be done non-destructively (with limitations depending on the tools available and the object to be tested).

That being said, if you need to check the hardness of a part going all the way from the surface to the core (walk-in hardness), you will likely have to cut the part perpendicular to the direction you want to test hardness in.

The basic rule is that if the componenet can be put into service after the test without a detriment to its properties or service life, then it is a non-destructive test.


"Metal Health'll cure your crazy
Metal Health'll cure your mad
Metal Health is what we all need
It's what you have to have"

-Quiet Riot
Bang Your Head (Metal Health)

 

[MetalHead83]

Apologies to metenger, I mis-read his post. He is, of course, correct. But with exception, some surface hardness checks can be done non-destructively.


"Metal Health'll cure your crazy
Metal Health'll cure your mad
Metal Health is what we all need
It's what you have to have"

-Quiet Riot
Bang Your Head (Metal Health)

 

[1gibson]

Is stamping for material traceability considered "destructive" ? What about centerline marking duing fabrication fit-up procss? Surely the 'destruction' of leaving a small surface divot falls within acceptance criteria for 99.9% of metallic components.

Both seem releveant, and I'm particularly curious about the stamping.

 

[redpicker]

I think people are becoming too hung-up about the "non-destructive" terminology. The important part of NDT is the "testing" part, not the "non-destructive" part. NDT is a catch-all term used to describe various test methods used to detect flaws in materials. The term "non-destructive" is used because other types of testing used to detect flaws (i.e., proof testing, pressure testing) can cause damage the material, particularly if flaws are present. NDT methods, on the other hand, do not cause any damage whether the material contains flaws or not. The term "non-destructive" is used in a descriptive sense, to describe a sub-set of material evaluation techniques that all share similar quality control requirements. It is not intended to be used in a definitive sense as some here are trying to use it. Get a copy of SNT-TC-1A if you need to see exactly what characterisitcs a particular medhod needs to have to be considered NDE.

There are many types of tests performed on materials that do not cause damage. Most dimensional measurements, for example, do not cause any damage, but nobody considers these tests as being NDT. Same for weight, not to mention counting quantity.

Whether or not stamping for traceability is considered "destructive" or not is dependent on the nature of the stamping and the application and really has nothing to do with NDT.

rp

 

[mrfailure]

redpicker raises an excellent point about semantics and terminology. I think it is important to consider what hardness technique is "nondestructive" in the sense that testing prevents use of the part in service. I thus agree also with Mike Halloran's comments: Equotip/Leeb tests are designed to be nondestructive as are other portable testing. However, bench testing by its nature destructive because you will not be able to use the part again for its intended purpose.

Aaron Tanzer

http://www.lehightesting.com

 

[shamino]

It's not technically considered an NDT method, although I can understand why you might think that. The main function of the NDT methods are to locate discontinuities in a component, such as a weld bead crack or porosity. Hardness testing is more along the lines of a destructive test in purpose, in that it is gauging the physical properties of the material.

The most common NDT methods (for those who aren't familiar) are visual, magnetic particle, liquid penetrant, radiographic, and ultrasonic.

More information at:

http://www.ndt-ed.org

 

[gearcutter]

"Is stamping for material traceability considered 'destructive'?"

Depending on where the stamping is placed; absolutely, stamping can be destructive.
I’ve done failure investigations on gears where a gear face is stamped near the root of a tooth creating a stress raiser in an already highly stressed area.
You can guess where the origin of the crack, which caused a tooth bending failure, was.


Ron Volmershausen
Brunkerville Engineering
Newcastle Australia

http://www.aussieweb.com.au/email.aspx?id=1194181