aluminum 6061-T651 versus T6511? 1

[mechengdude]

Can someone tell me what the signifigance of the "extra" 1 is when comparing the following two aluminum tempers?aluminum 6061-T651 versus T6511.

Thank you

 

[israelkk]

From MIL-HDBK-5J

T_511 Applies to extruded rod, bar, shapes and tube
and to drawn tube when stretched the indicated
amounts after solution heat-treatment or after
cooling from an elevated temperature shaping
process. These products may receive minor
straightening after stretching to comply with
standard tolerances.

T_51 Applies to plate and rolled or cold-finished
rod and bar when stretched the indicated
amounts after solution heat-treatment or
after cooling from an elevated temperature
shaping process. The products receive no
further straightening after stretching.

 

[mechengdude]

thanks for the fast response. that does the trick.