ASTM A350 LF2

[mechmateng]

Hi all,

I am dealing with a non-compliance at my work wherein a few of our products, manufactured in China, have been stamped with A350 LF2 as per our material request and drawing requirements. The material has tested as having an average Charpy result of 5.7J, instead of the required 20. The mill cert states a Charpy result of 56J. Does any one know what the theoretical maximum impact values that can be achieved with an A350 LF2? I have not been able to find any values in literature, only standards that require a specific value be met.

Thanks!

 

[metengr]

What was the test temperature? It should be -50 deg F or (-45.6 deg C) for Class ` and 0 deg F (-18 deg C) for the higher strength, Class 2.

You only need to worry about minimum impact requirements, and not maximum. For Class 1 this is 20J (average of three specimens) and for Class 2 it is 27J(average of three specimens). Impact values can and should be higher than the minimum requirements and can have a wide spread due to variations in chemical elements and heat treatment (grain size), but as I said this is not relevant.

 

[redpicker]

While I have no idea how you would try to figure a theoretical maximum, I can say that 56J is not an unusual value. 5.7J is an unusual value. That's 4.2 Ft-Lbs, which I'm assuming is an average value. Way too low for the grade and indicates that either the chemistry or processing is not correct.

rp

 

[stanweld]

Did the location of ypour removal of the test coupons for impact testing meet SA-350? The forgings could have been mixed, I have seen that in the past; check chemistry for fine grain melting. The values reported by the Chinese mill could also be fraudulent - certainly not unknown.

 

[mechmateng]

Thanks, stanweld. Your comments are the most relevant to my situation. I have ordered EDX, microstructural analysis, and a temperature spectrum test.

metengr - it is relevant to me. I am intelligent enough to have confirmed the testing temperatures, and have cross referenced the ASTM standard with the standards applicable to my industry (ASME, NACE, CSA etc.). I am also aware of the testing requirements.

The reason I am concerned with the theoretical maximum is because I believe the Chinese testing facilities are not actually performing the test, or are testing a different material. The values indicated on the mill cert are 10x the tested value, and with a discrepancy this high it begs the question - should we have seen a red flag on the mill cert?

redpicker - thank you for indicating that 56J is not unusual - can you speak to how high the impact strength can get?

 

[redpicker]

redpicker - thank you for indicating that 56J is not unusual - can you speak to how high the impact strength can get?

No. I thought I covered that with "I have no idea how you would try to figure a theoretical maximum". I would become curious at reported values over 150 Joules, though, even though I've seen impact specimens stop the hammer on a 300 Ft-Lb (400J), that was not a carbon steel (and not recommended).

rp

 

[metengr]

The reason I am concerned with the theoretical maximum is because I believe the Chinese testing facilities are not actually performing the test, or are testing a different material.

Unfortunate because the only way you will determine if values are near correct or true is to test the material at a 3rd party lab under your witness. Otherwise, trying to use a theoretical maximum and accusing the mill of fabricating test results will hold no water, and will be a complete waste of your time.

 

[Metalguy]

Redpicker,

Hope you examined the tup after the specimen stopped the hammer. Don't ask how I know. <g>

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[stanweld]

mechmateng,
I have seen -50 F absorbed energy well in excess of 100 ft-lbs in SA 350 LF2 forgings. As per metengr, it's a waste of time using a maximum absorbed energy value to gage the veracity of MTR results. I have also seen forging manufacturers heat treat the Charpy coupons in a lab furnace and record those absorbed energy values on its MTR. In those instances, I eventually rejected the forgings and had them remade and the removal of coupons and impact tests therefrom witnessed.