The most generally accepted X-ray method at the present time 

 is the sln^y. method which involves four or more X-ray exposures 

 at different angles of incidence whereby lattice strain components 

 are measured at such angles. This method has been proven by recent 

 investigations^ to be more accurate and reliable than the classi- 

 cal methods (one or two exposures), especially if the material is 

 anisotropic and contains plastic deformation. This report deals 

 with the application of the sin^'jf^ X-ray method for the determina- 

 tion of residual stresses in tee and circular weldments. 



OBJECTIVE 



The objective of this work was to determine residual stresses 

 in tee and circular weldments by X-ray diffraction film technique, 

 employing the sin^^p method, and to evaluate the effectiveness of 

 stress relief by heat treatment. 



PROCEDURE 



The study involved two types of Hy-130/150 steel weldments: 

 a circular fillet weld- test specimen (weldability specimen) and 

 a tee welded plate. The circular weldment consisted of a steel 

 disc, 6 inches in diameter and 2 inches thick, welded on a 15x15x2 

 inch steel plate along the disc circumference, as shown in Figure 

 1. The tee weldment, shown in Figure 2, consisted of a 15x15x1-^ 

 inch basal plate on which a stiffener, 2xl-|- inch cross section, 

 was welded along the middle of the plate. The two tyoes of 

 specimens were welded by the Gas Metal Arc process, using an M3 

 McKay filler wire. The tee weldment was saw-cut into 2 one-inch 

 wide sections perpendicular to the weld to provide specimens for 

 different heat treatments. 



Three sections were selected for stress analysis studies. One 

 section was left in the as-welded condition, another section was 

 stress relieved at 1025°P and water quenched, and the third was 

 furnace cooled after being stress relieved at the above tempera- 

 ture. The residual stresses were determined at the toes of the 

 welds in three azimuthal directions: parallel to the weld; 

 perpendicular to the weld; and 45° to the weld. Each specimen 

 was analyzed in three areas, equally spaced and aligned pareillel 

 to the weld, as shown in Figure 3. The analysis consisted of 

 four X-ray exposures for each azimuthal direction, at incident 

 angles {^ ) 0°, 15°, 30°, 45° from the normal to the specimen 

 surface. The lattice strains were calculated from the equation 



(1) Strain = ^ 



where AS is the diffraction line-shift due to the presence of 



298 



