Ti 6/4 failed reduction of area 25% min. actual was 23.4% - Significance?

[Ironcountry]

Going for the retest was just wondering about the significance, used in an orthopedic implant.

 

[metengr]

The significance is the test sample did not meet the minimum elongation requirement. Either test again or find another heat of material.

 

[metengr]

Woops…… should have said RA and not elongation. By the way, what was the elongation value versus the minimum elongation requirement?

 

[Ironcountry]

Yes, I understand however my question was regarding material performance and perhaps questioning allowance for variation in testing. Test by mfg. met requirements. Thanks

 

[metengr]

There is no variance for a single test sample. This is why you run multiple test samples and based on the results you either accept or reject the material.

 

[Ironcountry]

Should have stated margin for error, do not have the test report yet for additional data.

 

[FennLane]

You must be testing to a specific standard and this should contain information regarding statistical scatter and confidence limits and any sampling techniques permitted.

If the standard simply calls for a minimum RinA of 25% and you can report only 23.4 it , as has been said, failed to meet the required value and to use it for manufacture and implant it would be a real headache if it failed and you could only show this result.

How did you measure the reduction in area? and how many operators checked the result?

How much comparitive data do you have from previous batches?

Just to re-test after a failure is not an ideal result.

I used to sell Tensile Test machines with software that had been vaidated and the number of customers that asked how results could be edited was very high and defeats the entire objective. If it fails it fails.

I also sold many fatigue test machines for testing Hip Joints and the test regimes that were used in the standards were extremely well written and very well established.

I would imagine that this could be a very big deal aand I would worry if I were to entirely satisfied with the test results. The potential for litigation could be enormous and keep lawyers smiling for years.