Ti-6Al-4V线材电弧增材制造的组织与性能研究

Microstructure and Properties of Ti-6Al-4V by Wire+Arc Additive Manufactured

摘要:

本文采用Ti-6Al-4V线材为原料,以电弧为热源将钛合金丝材进行熔融,逐层进行堆积的快速增材制造,并对合金的凝固过程、组织形貌和力学性能等进行分析。结果表明,在丝材电弧增材制造过程中,在开始堆积的1~2层为柱状晶,随后的堆积则以等轴晶的方式生长。而且电弧高的热量输出,使得每个堆积区-熔合区-堆积区得到了有效的冶金结合,没有明显的界面和钛马氏体,各区域的显微组织均为稳定的α+β片层组织以及接近的显微硬度值。与铸态Ti-6Al-4V相比,电弧增材制造的钛合金不仅初始β晶粒细小,而且α+β片层间距也较小,其抗拉强度相比铸态提高3.6%,延伸率提高37%,拉伸断口为韧窝状的韧性断裂,与铸态合金存在一定撕裂棱的准解理断口形貌差异明显。

Abstract:

In this paper, Ti-6Al-4V alloy wire was molten by electric arc and then deposited layer by layer for the rapid prototyping of additive manufacture. Morphology, micro-hardness and mechanical properties of Ti-6Al-4V alloy were analyzed. The results indicate that the deposit in the first and the second layers is in the form of columnar crystals and the rest are equiaxial crystals. Meanwhile, a fair amount of heat from arc ensures a good metallurgical bonding in all of zones (deposition zone, fusion zone and deposition zone), and eliminates both clear deposition-layer and martensite of alloy. The integral alloy gets the stable α+β lamellar structural and similar micro-hardness of all zones. Compared with as-cast Ti-6Al-4V alloy, titanium alloy in this work obtains finer initial β-Ti grain and shorter α+β lamellar spacing by Wire+Arc Additive Manufactured. The ultimate strength and elongation of Ti-6Al-4V alloy have increased by 3.6% and 37%, respectively. Besides the tensile fracture morphology of Wire+Arc Additive Manufactured alloy is ductile dimple clearly different from that of as-cast alloy tearing edged quasi-cleavage.