Abnormal Grain Coarsening of Laser Surface Remelting Rapidly Solidified TA15 Titanium Alloy

作者：Liu Bin^*; Fang Yanli; Li An; Zhang Shuquan; Wang Huaming

来源：Rare Metal Materials and Engineering, 2009, 38(6): 1005-1009.

• laser surface remelting
• rapidly solidified
• TA15 titanium alloy
• beta grains abnormal coarsening

Rapidly solidified microstructure of a laser surface remelted TA15 titanium alloy as a function of laser scanning speed and solidification cooling rate was investigated. Abnormal coarsening of beta grains in the rapidly solidified remelted zone was readily observed for the laser glazed TA15 titanium alloy irrespective of the rapid solidification cooling rate. The beta grains in laser remelted zone of TA15 titanium alloy were abnormally coarsened and their sizes were up to 10 to 20 times larger than that of the alpha grains or 32 to 62 times larger than that of the beta grains in the original material. The rapid solidification and grain growth of molten bath of laser surface remelting TA 15 titanium alloy was a process of directly epitaxial growth of the beta grains of the unmelted substrate at the contact of the melt-pool bottom. The rapidly solidified beta grain size in the laser remelted zone was determined by the beta grain size of unmelted base metal at the bottom of molten bath. During laser heating and molten bath forming in the surface of the TA 15 titanium alloy, beta grains of the unmelted base metal at the top of heat-affected zone nucleated, grew in an extremely short time owing to the extremely high temperature. Solid-state abnormal coarsening of beta grains on the unmelted base metal at the bottom of molten bath resulted in the abnormal coarsening of rapidly solidification structure in laser remelted zone of the TA 15 titanium alloy.

• 出版日期2009-6
• 单位北京航空航天大学