temperature of the head. In addition, the weld was more ductile than 

 the base metal at 70"? but less ductile at 1750°F. The combination 

 of lower strength and ductility at 1750"? would appear to account 

 for the localized bulging of the weld in the laterally compressed 

 skirt area of the head, and thinning and fissuring in the biaxial 

 tension strained curved area during forming. 



CONCLUSIONS 



The results of this investigation indicate that it is feasible 

 to hot press a heavy walled hemispheric head from welded titanium 

 alloy plate. However, the head produced during the course of this 

 investigation was not of acceptable quality because of fissuring in 

 certain areas of the weld deposit during the forming operation. 

 Tlie fissuring appeared to be attributable to: (a) the presence of 

 minor lack- of- fusion defects, primarily in the short-circuit weld, 

 which opened up during hot forming; and (b) undermatching of weld 

 strength and ductility with corresponding base plate properties at 

 the forming temperature of 1750°F (even though the weld overmatched 

 the base plate at room temperature) . 



Successful hot forming of welded titanium alloy plate would 

 appear to require that weld properties at least match those of the 

 base plate at the forming temperature, either by appropriate selec- 

 tion of weld filler wire or by design of the weld joint. In addition, 

 the welding process used to join the plates should be one that is 

 not prone to lack of fusion type defects. 



FUTURE PLANS 



A weldment in 4-inch-thick alloy titanium plate, similar to the 

 assembly described in this paper, is being fabricated and will be 

 used for further hot -press forming studies. This weldment will be 

 formed with the weld reinforcement intact, to reduce plastic flow in 

 the weld during the forming operation. An opportunity will thereby 

 be afforded to examine the effect of weld joint design on performance 

 during hot forming. 



REFERENCES 



1. Wolfe, R.J., Nagler, H., Crisci, J.R., and Frank, A.L. "Out- 

 of-chamber Welding of Ti-7Al-2Cb-lTa Alloy Titanium Plate' , Welding 

 Journal, 44(10), 443-457, (1965) 



2. "Titanium Welding Techniques", Bulletin No. 6, Titanium Metals 

 Corporation of American, New York 7, New York 



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