Xudong ZHANG
,
Wuzhu CHEN
,
Cheng WANG
,
Lin ZHAO
,
Yun PENG
,
Zhiling TIAN
材料科学技术（英）
3 mm thick 400 MPa grade ultrafine grained ferritic steel plates were bead-on-plate welded by CO¬2 laser with heat input of 120~480 J/mm. The microstructures of the weld metal mainly consist of bainite, which form is lower bainite plates or polygonal ferrite containing quantities of dispersed cementite particles, mixed with a few of low carbon martensite laths or ferrite, depending on the heat input. The hardness and the tensile strength of the weld metal are higher than those of the base metal, and monotonously increase as the heat input decreases. No softened zone exists in heat affected zone (HAZ). Compared with the base metal, although the grains of laser weld are much larger, the toughness of the weld metal is higher within a large range of heat input. Furthermore, as the heat input increases, the toughness of the weld metal rises to a maximum value, at which point the percentage of lower bainite is the highest, and then drops.
关键词:
Laser welding
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null
,
null
,
null
C.C. Chang C.P. Chou S.N. Hsu G.Y. Hsiung J.R. Chen
材料科学技术（英）
This study discusses the welding properties for the components of an aluminum-alloy ultra-high vacuum chamber and beam position monitor (BPM). The welding parameters include the modes of laser output (pulsed wave and continuous wave), welding speed, shield gas flow, welding bead structure, and focusing distance. The results showed that the welding defect rate of the pulsed wave type was larger than that of the continuous wave type. The crack in the welding bead reduced with decreasing welding speed. The fusion penetration of the welding bead was higher when the focusing distance was long enough to deepen into the welding material. Weld morphology during the experimental process revealed the proper flow of shield gas.The adaptability design of the welding bead structure in the preceding processes had more effect on overall welding structure and morphology.
关键词:
Laser welding
Haichao CUI
,
Fenggui LU
,
Xinhua TANG
,
Shun YAO
金属学报(英文版)
Particle redistribution occurred with the flow of pool fluid in laser welding aluminum composites. In order to investigate particle migration behavior, a numerical model was established on laser welding of ZL101-TiB2 composite. TiB2 migration coupling with fluid was realized. The volume-of-fluid (VOF) method was employed to track free fluid surfaces. The travel heat source was realized utilizing the workpiece motion in place of heat source motion, which made the heat load stable. Melting and evaporation enthalpy, recoil force, surface tension and buoyancy were considered in this model. Through the calculation it showed that the simulated weld cross section shape and particle distribution were in good agreement with experimental results.
关键词:
Laser welding
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null
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null
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null
徐萌萌
,
陈明和
,
王大刚
宇航材料工艺
选取TC4钛合金四层板加强结构中双层板为研究对象,采用激光穿透焊接工艺代替传统超塑成形/扩散连接(SPF/DB)工艺中涂止焊剂连接.借助ABAQUS有限元分析软件对超塑成形过程进行分析,得到优化的压力-时间(p-t)曲线,作为双层板超塑成形过程的气压加载曲线,进行实验验证.结果表明:成形后零件壁厚分布均匀,焊缝处无撕裂现象,与有限元模拟结果保持一致;用此新工艺代替传统SPF/DB工艺中的止焊剂具有可行性.
关键词:
TC4钛合金
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激光焊接
,
超塑成形
,
数值模拟
