Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Investigation of strengthening mechanism of commercially pure titanium joints fabricated by autogenously laser beam welding and laser-MIG hybrid welding processes
AU - Li, Ruifeng
AU - Zhang, Feng
AU - Sun, Tianzhu
AU - Liu, Bin
AU - Chen, Shujin
AU - Tian, Yingtao
PY - 2019/3/1
Y1 - 2019/3/1
N2 - In this study, in order to achieve a better understanding of the strengthening mechanism in the commercially pure (CP) Ti welds, autogenously laser beam and laser-MIG hybrid welding of 4.2 mm thick CP-Ti plates were performed and the correlation between microstructure, texture distribution and the mechanical properties were systematically investigated. Microstructural coarsening and increase in microhardness were observed in the HAZ and WZ. The tensile test results suggested the base metal was the weak point of the joint for both welding conditions. The EBSD observations confirmed that a large number of { 10 1 ¯ 2 } and { 11 2 ¯ 2 } twin grains occurred in the HAZ and WZ of both welded joints, while a higher concentration of these twin grains were found in the laser-MIG hybrid joints. High concentration of the twin grain boundaries can act as barrier to stop dislocation slip during deformation and therefore contribute to the strengthening of the welds. The existence of very small twin grains and acicular α phase in HAZ and WZ would equivalently reduce the averaged grain size and therefore induce an increase in strength based on Hall-Petch’s law. In addition, the averaged Schmid factor of BM is higher than that of the WZ and HAZ in both welding joints suggesting that the grain boundary sliding will take place preferably in BM during deformation so that the necking and fracture occurred in base metal during tensile tests of both welding joint specimens.
AB - In this study, in order to achieve a better understanding of the strengthening mechanism in the commercially pure (CP) Ti welds, autogenously laser beam and laser-MIG hybrid welding of 4.2 mm thick CP-Ti plates were performed and the correlation between microstructure, texture distribution and the mechanical properties were systematically investigated. Microstructural coarsening and increase in microhardness were observed in the HAZ and WZ. The tensile test results suggested the base metal was the weak point of the joint for both welding conditions. The EBSD observations confirmed that a large number of { 10 1 ¯ 2 } and { 11 2 ¯ 2 } twin grains occurred in the HAZ and WZ of both welded joints, while a higher concentration of these twin grains were found in the laser-MIG hybrid joints. High concentration of the twin grain boundaries can act as barrier to stop dislocation slip during deformation and therefore contribute to the strengthening of the welds. The existence of very small twin grains and acicular α phase in HAZ and WZ would equivalently reduce the averaged grain size and therefore induce an increase in strength based on Hall-Petch’s law. In addition, the averaged Schmid factor of BM is higher than that of the WZ and HAZ in both welding joints suggesting that the grain boundary sliding will take place preferably in BM during deformation so that the necking and fracture occurred in base metal during tensile tests of both welding joint specimens.
KW - Laser beam welding
KW - Laser-MIG hybrid welding
KW - Commercially pure titanium Laser-MIG hybrid welding Commercially pure titanium Strengthening mechanism Microstructure Texture Mechanical property
KW - Strengthening mechanism
KW - Microstructure
KW - Texture
KW - Mechanical property
U2 - 10.1007/s00170-018-2922-9
DO - 10.1007/s00170-018-2922-9
M3 - Journal article
VL - 101
SP - 377
EP - 389
JO - International Journal of Advanced Manufacturing Technology
JF - International Journal of Advanced Manufacturing Technology
SN - 1433-3015
IS - 1-4
ER -