薄壁钛合金T形接头摆动激光填丝焊组织与性能

doi:10.12382/bgxb.2021.0894

摘要/Abstract

摘要：

在摆动激光填丝焊接中,热输入是影响焊接接头组织与性能的关键因素,因此开展热输入与组织和力学性能的相关性研究,为进一步提高薄壁钛合金接头的力学性能提供数据支撑及相关理论依据。采用摆动激光填丝焊对2mm厚的TC4钛合金T形接头进行焊接试验,对比分析不同位置的微区组织与力学性能。研究结果表明:焊缝表面成形良好,无未熔合、气孔、夹渣等焊接缺陷;焊缝组织主要由α'马氏体和初生β相组成,并有少量的孪晶和位错产生;热影响区主要由母材中未发生相变的α相和α'马氏体组成;焊接接头硬度值在286~413HV之间浮动,其中焊缝区硬度值最高,与母材相比硬度值约提升38%,随着焊接热输入增大,相变生成α'马氏体越多,显微硬度增大;焊接接头平均抗拉强度为1076MPa,略高于母材,拉伸试件断裂位置为母材,断口呈现出韧性断裂特征;焊接接头平均剪切强度为679MPa,剪切试件断口起裂位置为焊缝内部,焊缝区断口呈沿晶断裂特征,热影响区断口呈解理和准解理穿晶断裂特征。

关键词: 摆动激光填丝焊, 钛合金, T形接头, 微观组织

Abstract:

In laser oscillating welding with filler wire, heat input is a key factor affecting microstructures and properties of the welded joint. Therefore, investigating the relationship between heat input and microstructures and properties can provide data support and theoretical basis for improving thin-wall titanium alloy welded joints. In this study, laser oscillating welding with filler wire is to join a 2mm thick TC4 titanium T-shape joint, and the microstructures and mechanical properties of different zones are analyzed. The result show that the weld surface is well-formed, with no defects such as incomplete fusion, pores, or slag inclusions. The weld microstructures are mainly composed of α' martensite phase and primary β phase, with a small amount of twins and dislocations. The heat-affected zone is mainly composed of α phase and α' martensite phase that have not undergone phase transformation in the base metal. The hardness value of the welded joint fluctuates between 286 and 413HV, and that of the weld zone is the highest, 38% higher than the base metal. With the increase of welding heat input, more α' martensite is formed due to phase transformation, and the microhardness increases as well. The average tensile strength of the welded joint is 1076MPa, which is slightly higher than that of the base metal. The fracture of the tensile specimen occurs at the base metal and shows characteristics of the ductile fracture. The average shear strength of the welded joint is 679MPa. The fracture starting position of the shear specimen is inside the weld, and the fracture in the weld zone shows characteristics of intergranular fracture. The fracture in the heat-affected zone displayed characteristics of cleavage and quasi-cleavage trans-granular fracture.

Key words: laser oscillating welding with flier wire, titanium alloy, T-joint, microstructure

武鹏博, 徐锴, 黄瑞生, 杨义成, 邹吉鹏, 曹浩. 薄壁钛合金T形接头摆动激光填丝焊组织与性能[J]. 兵工学报, 2023, 44(4): 1015-1022.

WU Pengbo, XU Kai, HUANG Ruisheng, YANG Yicheng, ZOU Jipeng, CAO Hao. Microstructure and Properties of Laser Oscillating Welding with Filler Wire of Thin Wall Titanium Alloy T-joints[J]. Acta Armamentarii, 2023, 44(4): 1015-1022.

图/表 15

图1 钛合金母材显微组织

Fig.1 Microstructure of the titanium alloy base metal

表1 试验母材和焊丝化学成分质量分数及母材力学性能

Table 1 Mass fraction and properties of the base metal and welding wire in the test

材料	Al	V	Fe	C	N	H	O	Ti	抗拉强度R_m/MPa	显微硬度/HV
TC4钛合金	6.30	4.11	0.018	0.024	0.007	0.001	0.140	剩余	1038	286
TC4焊丝	5.75	3.82	0.044	0.012	0.006	0.001	0.081	剩余

表2 摆动激光填丝焊工艺参数

Table 2 Processing parameters of laser oscillating welding with flier wire

激光功率/ kW	焊接速度/ (m·min^-1)	送丝速度/ (m·min^-1)	摆动方式	摆动频率/Hz	摆幅/ mm
4.5	0.8	3	圆形	100	1

图2 焊接接头拉伸试样示意图

Fig.2 Schematic diagram of the tensile specimen of welded joints

图3 焊接接头剪切试样示意图

Fig.3 Shear specimen diagram of the welded joints

图4 T形焊接接头宏观形貌及X射线无损检测结果

Fig.4 Macroscopic morphology and X-ray test results of T-type welded joints

图5 焊缝截面的宏观形貌图

Fig.5 Macroscopic morphology of the weld section

图6 焊接接头不同区域微观组织形貌

Fig.6 Microstructure morphology of welded joints in different regions

图7 焊缝TEM形貌图

Fig.7 TEM morphology of the welding line

图8 焊缝区XRD分析结果

Fig.8 XRD analysis results of the weld zone

图9 焊接接头显微硬度

Fig.9 Microhardness of welded joints

表3 焊接接头拉伸性能测试

Table 3 Tensile test of welded joints

试样编号	R_m/MPa		断裂位置
试样编号	数值	平均值	断裂位置
1-1	1071		母材区
1-2	1084	1076	母材区
1-3	1074		母材区

图10 焊接接头拉伸试样及断口SEM形貌

Fig.10 Tensile sample and SEM morphology of tensile fracture

表4 焊接接头剪切性能测试

Table 4 Mechanical performance test of welded joints

试样编号	剪切强度/MPa
试样编号	数值	平均值
2-1	682
2-2	685	679
2-3	671

图11 焊接接头剪切试件及断口SEM形貌

Fig.11 Shear specimen and SEM morphology of shear fracture

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