Zhu Z Y, Liu Y L, Gou G Q, Gao W, Chen J
Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu, 610031, China.
Department of Chemical and Materials Engineering, the University of Auckland, PB 92019, Auckland, 1142, New Zealand.
Sci Rep. 2021 May 11;11(1):10020. doi: 10.1038/s41598-021-89343-9.
Composite structures made of 2 mm-thick titanium and 10 mm-thick carbon steel are widely used in infrastructures such as long-distance gas transportation. However, cracking, which is caused by intermetallic compounds (ICs), is a dominate failure mode in welds of this structure. Thus, a common way to improve the in-service life of is reduce the number of ICs. In this paper, we employ a novel hybrid welding method to fabricate composite structures of TA titanium and Q235 carbon steel. Specifically, Ti and carbon steel is welded by laser and double Cold Metal Transfer (CMT) welding, respectively. The microstructure near the interface of Ti and steel is then examined using SEM, EBSD, EDS, with emphasis on the ICs in terms of chemical elements and morphologies. Results show that FeTi and FeTi are the main ICs near the interface, and responsible for the failure of the welds. The effect of welding heat input on the formation of ICs is investigated as well. Results show that ICs are smaller when the heat input is low. Under low heat input circumstance, the tensile strength of the weld can reach up to 420 MPa.
由2毫米厚的钛和10毫米厚的碳钢制成的复合结构广泛应用于诸如长距离天然气输送等基础设施中。然而，由金属间化合物（ICs）引起的开裂是这种结构焊缝中的主要失效模式。因此，提高使用寿命的一种常见方法是减少ICs的数量。在本文中，我们采用一种新型的混合焊接方法来制造TA钛和Q235碳钢的复合结构。具体而言，Ti和碳钢分别通过激光和双冷金属过渡（CMT）焊接进行焊接。然后使用扫描电子显微镜（SEM）、电子背散射衍射（EBSD）、能谱仪（EDS）检查Ti与钢界面附近的微观结构，重点从化学元素和形态方面研究ICs。结果表明，FeTi和FeTi是界面附近的主要ICs，并导致焊缝失效。同时研究了焊接热输入对ICs形成的影响。结果表明，当热输入较低时，ICs较小。在低热输入情况下，焊缝的抗拉强度可达420MPa。
