Study Of Dynamic Strain Aging Phenomenon Of 3004 Aluminum Alloy

3004 aluminum alloy is of considerable importance in making tow-piece beverage cans and has been widely used. In order to investigate DSA phenomenon of 3004 aluminum alloy systematically,such as how DSA has effect on flow stress and work-harding rate,it was subjected to electric tension test,OM microscope,TEM,EDS,low frequency internal friction etc.Furthermore, the mechanism of DSA,the interaction between solute atom atmosphere and dislocation in 3004 aluminum and the influence of precipitation on the inverse PLC effect within the region of the strain rate and temperature which inverse PLC effect occurs was discussed. The main experimental results list as follows:1,DSA of 3004 aluminum alloy occurs at a certain range of strain rates and temperature. Within the region of DSA occurring ,stress plates,a maximum in the variation of work-hardening rate and negative strain sensitivity appears.The translation temperature at strain rate 5.56×10-5s-1,2.78×10-4s-1,5.56×10-4s-1,5.56×10-3s-1 are 308K,312K,321K,345K respectively.2,At a certain frequency and temperature, the internal friction increase with the deformation. And there is not internal friction peak in the curve of relationship between internal friction and tempetature under two kinds of states,solid solution state,strained1%. But when the pre-strain is 2.7%,4% and 6%,internal friction peak appears,it is believed it was dued to the precipitation and high density of dislocation.3,The activation energy is 0.82ev at low temperature range, 1.16ev at high temperature range.According to the values of activation energy ,it is believed that Mg atoms are responsible for the DSA in 3004 aluminum alloy.It is that Mg atoms atmosphere pins mobile dislocation and leads to serrated yielding.4,There are lots of precipitation in 3004 aluminum alloy.With the increase of the temperature and strain, precipitation particle will grow up, and it leads to the decrease of the concentration of the solute atom .In result, the opportunity of that the mobile dislocation was pinned decreases. In this case, in order to pin the dislocation and lead out serrated yielding, the larger critical plastic strain is necessary, and, therefore, leads to the appearance of a positive temperature coefficient of εc ,inverse PLC effect occurs.5,Within the region of inverse PLC effect occurring,the dislocation density around the second phase increases with the deformation,and dislocation configuration becomes entwisting.EDS analysis results and X-rad diffraction show that the place which dislocation entwists exists Mg solute atom atmosphere.It is believed that DSA occurs at this place.