INVESTIGATION OF BONDING PHASE DIMENSION ON SHEAR STRENGTH OF SUPERALLOY BRAZED BY ACTVE FILLER MATERIAL

Year 2020, Volume: 4 Issue: 3, 52 - 58, 17.07.2020

Mudhafar Mohammed Saba Khathim

Abstract

In  this  study, Nickel 
based  superalloy  In 738 LC was 
brazed  by using  (Ni-Ti) 
and ( Ni-Ti-Al)  alloys which  are  an
active  filler  alloys 
under protective atmosphere ( using a 
high purity  99.999  Argon gas ). 
Five brazing temperatures (1135, 1025, 985, 825, 725 ºC) were chosen
based on the solidus temperatures of  
(Ni-Ti) and   (Ni-Al) filler
alloys in order to investigate the effects of these temperatures on the
performance of the brazed joints. Brazing processes were carried out over a
period of   time (15min)  to ensure 
that  the filler  alloys were 
melted  completely. The
performance of   brazing process was
evaluated in terms of bonding strength by shear test.  The results 
revealed that  a maximum
value  of shear  strength 
( 29MPa )  was  obtained 
at  brazing temperature ( 985ºC )
as compared  with other
temperatures.   It  was 
observed that  the  highest shear strength was  influenced 
by  the formation  of  (
Ni3Ti ) phase.   Micro - hardness  testing 
appears  a gradual  increasing 
in hardness  towards the  centerline of 
the  joint  indicating 
that  the  composition of  bonded 
layer consists  of  a hard 
intermetallic  phases  of  
varying  composition  at different depth.  The 
samples  bonded   by  (
5% Ni 5%Ti 90%Al )  at   825ºC  
revealed the  higher  value 
( 841.7 )  HV  due  to   intermetallic  and 
centerline  eutectic
constituents  in the center of  brazing seam.

Keywords

Brazing; Active filler alloy; Brazing temperatures; Nickel based superalloy; Shear strength

References

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