Impact test: Energy Vs Lateral Expansion

[marcolino21576]

Dear All,

I have lately submitted (for a new Project) a previously qualified WPS+PQR (according to ASME IX).

At PQR stage I carried out a certain no. of impact tests, reporting the results as energy absorbed [J].

Now, my accurate customer is rejecting the PQRs because project specification requires impact values expressed as "lateral expansion".

Values found at PQR stage are about 100J, and my customer is requesting 0.38 mm materal expansion minimum.

I know energy and lateral expansion are not the same thing, but I also know that they are somehow empirically related (100J would for sure result in lateral expansion values higher than 0.38 mm lateral expansion).

Apart carrying out new impact tests, do you envisage any possibility for us to solve the problem?

Thank you

Marco

 

[Metaljon]

What material grade are you testing?

http://nz.linkedin.com/pub/jonathan-smith/39/25/589

 

[Metaljon]

At 100J it should have passed the minimum lateral expansion requirement easily. The lateral expansion measurement can be quite tricky to measure accurately and subject to errors. We use image analysis software to do this measurement but some labs do it with a set of callipers. I would get the samples remeasured first before you redo your PQR.

http://nz.linkedin.com/pub/jonathan-smith/39/25/589

 

[marcolino21576]

Thank you Metaljon,

I am testing a cast alloy 6Mo (ASTM A351 CK3MCuN). I fully agree with you, the problem is that the submitted WPS/PQR was originarily issued 3 years ago, and I am no more in possess of impact test specimens to be measured.
So, I see just 2 solutions:
1) trying to convince customer that 100 J should be more than enough in order to guarantee a 0.38 mm lateral expansion minimum
2) carry out an annex to existing PQR, and re-test the impacts measuring lateral expansion.

Any other idea?

Thank you

Marco

 

[Metaljon]

I would try and convince your client that 100J would normally be expected to give adequate lateral expansion. In my experience, for an austenitic casting weld, lateral expansion of less than 0.38mm would be expected to be typical of a material having less than 30J impact energy. At 100J, I would expect lateral expansion of more than 1.0mm. What values of lateral expansion were reported? You could ask the lab who did the test to recheck their paper records.

http://nz.linkedin.com/pub/jonathan-smith/39/25/589

 

[marcolino21576]

Again, I fully agree.
Values are 101-106-99 J on HAZ and 90-89-92 on WM, therefore it's more than reasonable to assume lateral expansion values much higher than 0.38 mm (1.00 mm according my experience as well).
I will talk to the lab, or try to convince customer.
Will let you know how it develops

Thank you for your opinion on the subject

Marco