This variation in thickness was not due to thinning during forming 

 but to a malfunction in the tracer unit of the vertical boring mill 

 on which the head was machined. 



EVALUATION OF PROPERTIES 



Average properties of weld and base plate specimens, before and 

 after forming, rounded out to the nearest whole number for ready 

 comparison, are shown in Table 4. 



The data shown in Table 4 indicates that although the numerical 

 values of tensile yield and ultimate strength were not changed sig- 

 nificantly as a result of forming there was a trend in the way the 

 values changed. There was a slight loss of strength in the weld 

 metal and a slight increase in base -plate strength. The same trend 

 is evident in ductility as measured by elongation and reduction in 

 area. Ductility of the weld was reduced after forming^while that 

 of the base plate improved slightly. Charpy energy values were 

 generally lower in the weld after forming as compared with little 

 or no change in the base metal. The reduction in weld properties 

 after forming may be attributed, at least in part, to the presence 

 of the fissures previously noted, since many of the weld test speci- 

 mens contained these discontinuities. It is somewhat surprising, 

 however, to find that these discontinuities had such little effect 

 on the weld properties. 



A greater effect was observed in side bend tests performed on 

 weld specimens before and after forming. Three side bend specimens 

 of the weld, before forming, satisfactorily withstood 180° bends 

 over a 4T radius mandrel without rupture. Only one of two side bend 

 specimens removed from the formed weld satisfactorily withstood a 

 180" bend without rupture; the second specimen ruptured after bend- 

 ing to only 104°. 



MACRO -AND MICRO-SECTION ANALYSIS 



Typical macro-sections of the weld joint, before and after 

 forming, are shown in Figure 13. The clearly delineated weld passes 

 of the section before forming are no longer evident in the section 

 of t!".e ferried v;elJ. Tliis is to be expected since the forming opera- 

 tion was carried out above the beta transus temperature and homo- 

 genization of the cast structure has taken place in the weld area. 

 The outline of the cast weld metal, however, is still visible in 

 the formed section. An outline of the formed macro-section has been 

 superimposed on the as-welded section and it is evident that, for 



108 



