ASME STP-PT-086:2017 pdf free download

ASME STP-PT-086:2017 pdf free download.EFFECTS F HIGH TEMPERATURESANDFIT-UP FRIVETED JOINTS DN STEEL RIVETS.
A combination u readings Ironi the gun and color recognition was used and both indicated at least
2250 degrees F (1230 degrees C) was attained, and probably higher temperature in some cases for the
extended soak time rivets of 10 minutes and 20 minutes, It was felt that a higher temperature made the test
results cvcn more conservative, Some rivets in the gas furnace achieved 2300 degrees F (1260 degrees C)
before being driven, again resulting in more conservative results.
When the rivet achieved the temperature and time requirements above, it was removed from the heat SOUrCe with tongs and placed in the hole. The riveter on the bead end seated the rivet with the gun off and then started thai gun first to ensure that the head is seated properly on the sheet and there is no chance of the rivet being pushed out of the hole any distance. Once the head gunner was up and running the gunner on the shank end turned his gun on and began to form the head. Upon completely forming the head, the shank gunner stopped his gun bet maintained bucking pressure on the rivet. The head gunner stopped his gun after the shank gunner. This process ensured that the rivet was not hammered without bucking on the other side. Typically, when the guns arc removed from the rivet, the very center of the head will be a dull red color. The plates were not pre-heated prior to driving the rivets.
The rivets in the 1)8-inch (3.2 mint oversized holes were longer than rivets for a 1/16-inch (1.6 mm) oversi,ed hole by the amount necessary to ensure filling the hole and having enough material to form a full head on the shank end. Because more material needed to be moved in this test, the rivets were mostly devoid of any red heat color when riveting was completed.
In the plates that were made to spring back, the first rivet driven was furthest from the fulcrum (9 inches) and the plates were spread approximately 1116-inch 1.6 mrn to 3132-inch (2.4 mm). A lit-up like this would be an extreme case in a normal riveting job and would be considered nearly unacceptable practice. Typically, this rivet drew the plates together on the end as the rivets were formed. The nest two rivets were driven in holes located between the first rivet and the fulcrum, with a plate spread of 1132-inch (0.8 mm) to 116-inch (1.6 mm). The plate would have been less free to bounce than with the first rivet, however it would have rebounded imre positively albeit a shorter distance, Both these rivets drew the plates closer together.
Test 3 was performed to determine if extended soak times adversely affected the rivet, and was done in the same manner as Test 2 except that the rivets were heated in a gas fired forge. and had extended soak times of 10 minutes and 20 minutes at tcmperalure before driving.
2. A review of elongation values revealed a decreasing trend for rivets hot driven at 2250 degrees F (I 23() degrees C) or at 1950 degrees F (1065 degrees Ct. The decrease is counter to the increase in ROA. which is a true measurement of ductility because it is unaffected by gage length or spccimcn size effects. The decrease, which appeared to he consistent, may have been caused by the use of a sub-site tensile specimen machined from the shank of the hot driven rivets.
3. The increase in tensile properties for steel rivets driven at 2250 degrees F(1230 degrees C) and driven at 1950 degrees F (1065 degrees C) was most likely caused by the combined effects of dynamic recrystallization and associated transformation products during cooling from the austcnitizing temperature range of 1950 degrees F 1065 degrees C) or 2250 degrees F (1230 dcgrccs C). The rivets were fully atistcnitizcd because the rivets were above 1650 degrees F (g95 degrees C), which is considered the minimum temperature for complete austenitization). During riveting of austenitized rivets, the hot defixrnation resulted in dynamic recrystallization (smaller grains). Metallographie examination confirmed the presence of pockets of recrystallized grains and colonies of local transformation products after cooling.