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# How accurate is hardness testing to determine depth of HAZ?2

## How accurate is hardness testing to determine depth of HAZ?

(OP)
I need to test a welding sample of pipe to see how deep into the wall the HAZ extends. Our testing facility can do hardness testing, but not etching for seeing microstructure. How accurate would hardness testing be to determine HAZ depth?

If it can be done well enough, what precautions should I take with sample cutting/preparation?

Thanks.

### RE: How accurate is hardness testing to determine depth of HAZ?

You require to carry out micro hardness for the same (sans etching). It is much more costly than conventional hardness testing machines and most probably your testing facility does not have it.

DHURJATI SEN
Kolkata, India

### RE: How accurate is hardness testing to determine depth of HAZ?

2
You should be able to macro-etch the weld and HAZ and base metal adjacent to the HAZ. You need not polish and etch for microstructure evaluation. I've used muriatic acid purchase through a swimming pooll supplier to do reveal the HAZ depth many times in the field.

### RE: How accurate is hardness testing to determine depth of HAZ?

(OP)
Great to hear it, Weldstan. Searching the web for "macro-etching" returns many links to this process, which I've yet to look into, but will shortly. In your opinion, is it difficult to learn from such sources well enough to do an adequate analysis? Do you have any references you'd suggest for self-educating on this?

### RE: How accurate is hardness testing to determine depth of HAZ?

Metals Handbooks. As a metallurgist, I was taught the techniques almost 60 years ago and have simply done it for years. I had a great book, "Metallurgy and Metallurgical Engineering" by George Kehl that I used for decades. You may be able to obtain a copy on eBay.

### RE: How accurate is hardness testing to determine depth of HAZ?

(OP)
weldstan,

I found a video showing macroetching and while I see a definite line showing the weld penetration, but if the HAZ is shown (~5:20 mark), I'm not able to make it out. Are the samples you make made similarly (prep starts ~1:20 mark)?

I am currently trying to obtain the relevant ASTM standards for macroetching metals, and have contacted some local test labs in case I'm not confident in what I find. I'm not trying to engineer by youtube....

### RE: How accurate is hardness testing to determine depth of HAZ?

While you don't need to polish for this the smoother the surface the clearer it will be.
A good cut followed by a belt sander is often used.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

### RE: How accurate is hardness testing to determine depth of HAZ?

ASTM E340 and E381 are the relevant standards for macroetching. You can purchase on techstreet.com; a PDF of E340-15 costs $56 USD, PDF of E381-22 costs$54 USD.

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