Page 306 - 00. Complete Version - Progress Report IPEN 2014-2016

306 Materials and Nanotechnology | Progress Report

these parts in the conical connection and the
force required to remove the abutment in or-
der to check whether they were greater than
the force of chewing.

Figure 27: (a) Scanning electron microscopy image with back-scat-
tered electrons showing the implant / abutment adjust-
ment without maladjustment, see detail indicated by red ar-
rows. (b) Gap of 0.5 µm in the part of the neck of the implant.
Grade 91 welded joints

Grade 91 steels have been widely used in com-
ponents to work at high temperatures in power
generation plants, petrochemicals and oil re-
fineries due to their excellent creep and cor-
rosion resistance. Despite these remarkable
properties, some difficulties in welding Grade Figure 28: (a) Welded joint between tube and curve - Dimensions
91steels have been encountered, as they may in millimeters (b) Influence of the tempering time in the vari-
ous welding regions (c) Surface of the fracture region, the top sam-
exhibit hardness values outside the specified ple without lateral expansion of the weld metal (WM-CS) and the
limits leading to a reduction of some mechan- bottom samples with lateral expansion of the weld metal (WM-
8h) (d) Energy absorbed in the impact test x welded joint regions
ical properties. In this study, Grade 91 tubular and (e) Lateral expansion in WM in the top and in the root.

Instituto de Pesquisas Energéticas e Nucleares