Hello,

We recently tested a pipe weld in As-Welded and PWHT condition for Weld Procedure Qual.

The Charpy results from Weld shows 5, 7 and 170 ft-lbs, the HAZ (Center of HAZ) shows 7, 60, 138.... I made sure that the samples were
extracted from the Weld and HAZ. One of the broken HAZ Charpy shows inclusion type defect but the rest are okay.

Any idea or suggestion that can explain the results above ? Should i test another set ?

Thank you.

You mention CVN testing on as-welded and PWHT weld coupon. What do the above CVN test results pertain to, as-welded or PWHT condition?

What was the base material composition and weld metal?

What was the welding process?

Bottom line we need more background information to provide advice.

List of possibilities;
1. Weld defects - porosity, inclusions, lack of fusion
2. Insufficient PWHT temperature or time.
3. Poor technique or set-up for welding resulting in harmful phase constituents – untempered martensite. You would need to verify this by metallographic examination of the CVN test specimens, and not just a visual examination.
4. Lack of preheat
5. CVN testing not performed with calibrated machine or improper notch radius.
...... and the list goes on.....

I would go through and evaluate each of the above and re-do the weld procedure impact coupon.