دانلود رایگان مقاله توانایی لحیم کردن عیار درجه 2 تیتانیوم و آلیاژ منیزیم AZ31B تحت پوشش شار

ABSTRACT

The article presents the basic issues related to brazing of poorly brazeable materials such as titanium and magnesium alloys. The text contains exemplary chemical compositions of fluxes used in brazing of poorly brazeable materials and presents the results of composition and technological process-related tests concerning fluxes used for brazing of Grade 2 titanium and AZ31B magnesium alloy. The article also presents the brazing properties of fluxes and test results concerning the mechanical properties of brazed joints as well as the results of metallographic examination utilising light and electron microscopy.

5. Conclusions

1. The test results concerning the spreadability of the Ag 245 brazing filler metal on the surface of titanium, using the F60T flux, revealed that it is possible to develop flux not containing expensive and light-sensitive silver chloride (AgCl). This compound can be replaced by, e.g. zinc chloride (ZnCl2), which does not undergo light-induced decomposition. 2. The most advantageous test results concerning the brazing properties of fluxes as well as the quality and strength of brazed joints made of Grade 2 titanium using fluxes and the Ag 245 brazing metal were obtained for the F60T flux containing such compounds as KF2H2O, KHF2, LiCl and ZnCl2. In turn, in the case of the joints made of the AZ31B alloy brazed with the MgAl9Zn3Mn1 magnesium filler metal the best results concerning brazing properties were obtained for the flux designated as FMAG, containing such compounds as KCl, LiCl H2O, CaCl2 and NaF. 3. The activity of the developed flux F60T is sufficient within the temperature range 550–800 8C, whereas the activity of the FMAG flux is sufficient within the temperature range 450–600 8C. 4. The F60T flux enables obtaining proper brazed joints both by C2H2–O2 flame heating and by induction heating. In turn, the FMAG flux is recommended for flame brazing of the AZ31B magnesium alloy using the MgAl9Zn3Mn1 magnesium filler metal. 5. The brazed overlap joints made of Grade 2 titanium using the Ag 245 brazing metal and the F60T flux were characterised by good quality and relatively high shear strength amounting to 163 MPa. In turn, the overlap joints made of the AZ31B magnesium alloy using the MgAl9Zn3Mn1 magnesium filler metal and FMAG flux were characterised by good quality and shear strength amounting to 47.6 MPa. After brazing the joints contained relatively small amounts of flux slag.