Research Of Ultrasonic Vibration Effect On Q235 Steel During Hot Deformation Process

In order to set up the Q235 steel mathematical models calculating the deformation stress at high temperature,the in-house made micro-computer aided hot pressing machine was construct for the experiment and the original austenite grain boundary was observed by metallographic microscope.The mathematical models also based on the existing models describing the low-carbon steel deformation stress models and the austenite recrystallization and grain size evolution models,which were implemented into finite element analysis through user defined subroutine VUMAT.The experiment equipment was designed for describing ultrasonic vibration exciting metal hot forming process and the exponential horn was designed.To analyze the effect of large deformation macroscopic deformation conditions on Q235 steel undergoing hot forming process with ultrasonic vibration,the hot compression simulation experiments carried out on cylinder specimens of Q235 steel was analyzed by ABAQUS software.The orthogonal test table was correctly chosen,which combined with the typical macroscopic deformation conditions.The results show that dynamic austenite recrystallization occurred in advance and the average austenite grain size became smaller when Q235 steel specimen is excited by ultrasonic vibration during hot temperature.It is found that the specimen became a drum without ultrasonic vibration while part of specimen excited by ultrasonic vibration looked like elephant foot at the same deformation degree of 40 percent.The results also indicated that the factors could be sequenced for austenite grain size refinement degree :the specimen height rate?frequency ?amplitude?strain rate?deformation temperature.In the above factors,deformation degree affected obviously the maximum value of average austenite grain size in the Q235 steel cylinder sample,other factors could be ignored.