Daqian SUN
,
Zhenan REN
,
Zhenfeng ZHOU
,
T.North
,
Yang ZHAI
,
S.Sathian
材料科学技术（英文）
Microstructural features of friction-welded Ti-6Al-4V joint have been investigated by both optical microscope and transmission electron microscope (TEM). The microstructure of the welded joint is not uniform. It can be classified into the phase transformed region(P), the deformed region(D) and the region of unchanged base metal(B). In the phase transformed region, the microstructure consists of platelike, acicular and equiaxed alpha phase plus beta phase between them and the dislocations can be observed in some or phase particles. The equiaxed alpha phase mainly distributes in the near center of rod specimen. The quantity of platelike and acicular alpha phase and the size of the grains increase progressively along the radial direction of the rod type welded joint. In the deformed region, the grains are reoriented and the microstructure consists of the elongated alpha phase containing a lot of dislocations and intergranular beta phase.
关键词:
Daqian SUN
,
Zhenfeng ZHOU and Haicheng CAO (Dept. of Mater. Sci. Eng.
,
Jilin University of Technology
,
Changchun 130022
,
China)
材料科学技术（英文）
Effect of Si, Al and Bi on the microstructure and mechanical properties of as-welded and austempered ductile iron weld metals has been studied with SEM, TEM, X-ray diffraction, image analysing system, tension and other test methods. Results show that increasing weld Si, Al and Bi content favours improving the chilling tendency of as-welded ductile iron weld and mechanical properties of austempered ductile iron weld and the mechanism is also discussed. On this basis the optimum chemical composition of weld is determined. The mechanical properties of weld and welded joint after austempering can match those of austempered ductile iron
关键词:
Daqian SUN
,
Zhenfeng ZHOU
,
Wenquan WANG
,
Lian LIU
材料科学技术（英文）
The effects of Si, Mn and Al on the microstructure and mechanical properties of ADI weld have been studied. The microstructure of ADI weld metal mainly consists of bainitic ferrite and retained austenite. Mechanical properties of ADI weld increase with increasing Si content, but an excess of Si(3.79%) results in decreasing the austemperability owing to decreasing the carbon content of the matrix austenite. Mn increases the retained austenite volume fraction, but the ductility and impact toughness of weld obviously decrease with increasing Mn content because of increased amount of martenite and twin martenite. In the range of 0.13%~0.64%, increasing Al content favours improving the mechanical properties of ADI weld. Therefore, it is very important to select suitable Si, Mn and Al contents to improve mechanical properties of ADI weld.
关键词:
ADI weld metal
,
null
,
null
