AMS 4919 Forming Cracks 1

[Callie81]

I'm currently working on my first real failure investigation on some AMS 4919 (Ti 6242) formed parts. The parts in question have a material thickness of .034", and are formed in annealled condition. Parts at the time of forming are without alpha case contamination, However, we are seeing a high rate of failure during forming on the bend radius. I feel that these fractures are occuring due to surface defects (pits, scratches) in the bend radius. I am going to further investigate this problem, however I would like your opinions to whether this would be a valid hypothesis. Also, beyond verifing that there is no alphacase/surface contamination and observing the fracture surface, what other methods of analysis would you recommend.

Callie
Lab Manager

 

[TVP]

"Annealing" is an extremely vague term when describing the thermal treatments of alpha-beta titanium alloys like Ti-6242. I would confirm the exact time and temperature profile used, and whether or not the microstructure corresponds to such a treatment. What are the details of the bending process? Could be as simple as the strain induced during bending exceeds the normal workability limits of this grade?

 

[Callie81]

The anneal consists of 1650F+-25 for 30 min Vac Argon Quench. The forming particulars I'm not all that sure on. The problem in the past has been midigated by acid pickle and/or polish and heat. However, without a valid idea why the cracks are taking place, I cannot define the more appropriate procedure.

Callie