Characteristics of commercial vacuum-hot-pressed beryllium. III. Effect of heat treatment and pressurization on the properties of hot-pressed block HY. Summary report [report]

S.H. Gelles
1974 unpublished
Continuing work to characterize hot-pressed beryllium block K which had shown brittle behavior in the pressing direction at 500 F (260 C) has been concerned with the effect of heat treatment and pressure treatment on the structure and tensile propettles of the metal. The heat treatment consisted of 8 hours at 1090 C (1994 F) followed by a cool at a linear rate to 750 C (1382 F) in 8 hours and then cooling to room tem perature in 24 hours at a linear rate. Tensile properties were evaluated at
more » ... ere evaluated at T^om temperature, 300 and 500 F (149 and 260 C, respectively), at strain rates of 0.0385 and 38.5 per minute. The heat treatment reduced the yield and ultimate tensile strengths, improved the tensile ductility, and somewhat reduced the ten dency for embrittlement at the slower strain rate. However, at a strain rate of 38.5 per minute, pronounced embrittlement was still observed in the pressing direction at both 300 F (149 C) and 500 F (260 C). Structural changes accompanying the heat treatment consisted of a small increase in grain size (8.8 to 11.2 u), a small decrease in density (1.853 to 1.851 g/cm ), and changes in the size and type of minor phases present in the structure. The pressurization treatment to 21,000 atmospheres (308,600 psi) was found to restore the ductility of the as-received samples of hotpressed block HY. This observation has pinpointed the source of embrittlement in this material and in a hot iaostatically pressed P-21 sample similarly treated as a deficiency In mobile dislocations probably due to solute, precipitate, or inclusion pinning, vi :::!Smm^B<vi'!!&sXi^imss;:s:z SUMMARY REPORT
doi:10.2172/4246928 fatcat:o53wuyycr5hndgl6u7zxjyt6ym