TC21钛合金线性摩擦焊接头组织及性能分析

Microstructure and Properties of Linear Friction Welded Joint of TC21 Titanium Alloy

摘要:

本文对TC21钛合金进行线性摩擦焊接试验,采用OM、SEM等测试手段对接头各区域显微组织演变规律进行了分析,并通过显微硬度仪和电子万能试验机对接头显微硬度及拉伸性能进行测试。结果表明：TC21钛合金线性摩擦焊可以得到良好的焊接接头,接头明显分为母材区、热力影响区和焊缝区；焊接过程中焊缝区发生了相变及动态再结晶过程,形成细小的再结晶晶粒,板条状α相在晶界处析出,针状马氏体α′相在晶粒内部析出,并有少量的残余α相保留至室温；热力影响区主要以变形α相为主,随着向两侧母材靠近,再结晶程度逐渐减弱,α相比例逐渐增加。由于飞边形成阶段及焊后冷却速率大小不同,导致沿着焊缝中心向飞边端部靠近,晶粒尺寸逐渐变大。TC21钛合金线性摩擦焊接头显微硬度呈拱形分布,焊缝中心显微硬度值达到最大值460HV,拉伸性能测试结果表明,接头强度与母材相当。

Abstract:

In this paper, the linear friction welding of TC21 titanium alloy was investigated. The microstructure evolution of each region of the joint was analyzed by OM and SEM. The microhardness and tensile properties of the joint were tested. The results showed that a sound weld joint can be obtained using LFW. The joint was obviously divided into base metal zone(BM), thermo-mechanically affected zone(TMAZ) and weld zone(WZ); during the welding process, phase transformation and dynamic recrystallization took place in WZ, forming fine recrystallized grains, lath α precipitated at grain boundary, acicular martensite α phase precipitated inside grain,and a few residual α phase reminded at room temperature. Away from the weld center,the degree of recrystallization gradually decreased and the proportion of a phase gradually increased,the grain size gradually increased from the weld center to the end of flash. Due to the different of flash formation phase and cooling rate after welding. The microhardness of TC21 titanium alloy linear friction welded joint is arched,and the maximum value of microhardness in weld center is 460HV. The tensile test results indicated that the strength of the joint is equivalent to that of the base metal.