158
T. Das
σ C = (1 + 0.5 V f )
σ m + σ T + σ 0 +
σ 0 σ T
σ m
where,
σ T = 1.25 Gb
12T C V f
bd p
σ 0 = 0.13 Gb
ln
d p
2b
d p
1
2V f
1
3 − 1
where σ C = composite yield strength, σ m yield strength of the matrix, σ T yield strength
increment owing to the thermal mismatch, σ 0 = yield strength enhancement owing
to the Orowan looping around multi-walled carbon nanotubes, G = matrix’s shear
modulus, b = matrix’s burgers vector, T = processing and testing temperatures
difference, C = difference amongst the thermal expansion coefficients of the matrix
and multi-walled carbon nanotubes, V f = volume fraction of multi-walled carbon
nanotubes and d p = mean size of multi-walled carbon nanotubes.
Conclusions
From the comparative study of the effect of graphene nanoplatelets and multi-walled
carbon nanotubes interlayers on the RSW of similar metals (AISI-1008 steel), the
resulting conclusions are stated:
(a) Graphene nanoplatelets and multi-walled carbon nanotubes used as interlayers
enhanced the weld strength of the joints by ~49% and ~45%, respectively, at
optimum welding conditions. The introduction of graphene nanoplatelets and
multi-walled carbon nanotubes as interlayers helped in the increase of ductility
and reduction of brittleness.
(b) The microstructural analysis showed well-bonded joints and refinement of
grains that occurred in the fused zone. Graphene nanoplatelets and multi-walled
carbon nanotubes were found to be embedded in the lath martensitic Fe matrix
in the fusion zone. Dislocations got piled up at the grain boundaries, and load
transfer took place efficiently from the graphene nanoplatelets /multi-walled
carbon nanotubes to the Fe matrix by the interfacial shear stress transfer as
observed from the TEM study.
(c) X-ray diffraction study discovered the existence of elemental iron (Fe) peaks
in the fractured specimens in both the graphene nanoplatelets /multi-walled
carbon nanotubes coated samples. Elemental carbon peak was noticed in the
specimens, and also, iron carbide and oxide formation were detected.
T. Das
σ C = (1 + 0.5 V f )
σ m + σ T + σ 0 +
σ 0 σ T
σ m
where,
σ T = 1.25 Gb
12T C V f
bd p
σ 0 = 0.13 Gb
ln
d p
2b
d p
1
2V f
1
3 − 1
where σ C = composite yield strength, σ m yield strength of the matrix, σ T yield strength
increment owing to the thermal mismatch, σ 0 = yield strength enhancement owing
to the Orowan looping around multi-walled carbon nanotubes, G = matrix’s shear
modulus, b = matrix’s burgers vector, T = processing and testing temperatures
difference, C = difference amongst the thermal expansion coefficients of the matrix
and multi-walled carbon nanotubes, V f = volume fraction of multi-walled carbon
nanotubes and d p = mean size of multi-walled carbon nanotubes.
Conclusions
From the comparative study of the effect of graphene nanoplatelets and multi-walled
carbon nanotubes interlayers on the RSW of similar metals (AISI-1008 steel), the
resulting conclusions are stated:
(a) Graphene nanoplatelets and multi-walled carbon nanotubes used as interlayers
enhanced the weld strength of the joints by ~49% and ~45%, respectively, at
optimum welding conditions. The introduction of graphene nanoplatelets and
multi-walled carbon nanotubes as interlayers helped in the increase of ductility
and reduction of brittleness.
(b) The microstructural analysis showed well-bonded joints and refinement of
grains that occurred in the fused zone. Graphene nanoplatelets and multi-walled
carbon nanotubes were found to be embedded in the lath martensitic Fe matrix
in the fusion zone. Dislocations got piled up at the grain boundaries, and load
transfer took place efficiently from the graphene nanoplatelets /multi-walled
carbon nanotubes to the Fe matrix by the interfacial shear stress transfer as
observed from the TEM study.
(c) X-ray diffraction study discovered the existence of elemental iron (Fe) peaks
in the fractured specimens in both the graphene nanoplatelets /multi-walled
carbon nanotubes coated samples. Elemental carbon peak was noticed in the
specimens, and also, iron carbide and oxide formation were detected.