Microwave sintering of different industrial parts of varying shape and geometry was also
performed. Comparable properties to conventionally sintered parts can be obtained using a
microwave sintering temperature that is 50–80 C lower than conventional sintering.
In another study by Panda et al. [46] on the effects of conventional and microwave sintering
on ferritic (434L) and austenitic (316L) stainless steel, it was reported that the heating rate for
microwave sintering is affected by the composition of the stainless steel powder, with ferritic
stainless steel samples displaying a slightly faster heating rate, compared to austenitic stainless
steel samples due to differences in its coupling with microwaves.
The densification of the samples is also affected by the crystal structure of the powder,
with ferritic stainless steel achieving a higher densification than austenitic stainless steel,
which was attributed to higher diffusivity in the less densely packed body center cubic
structure of the ferrite phase [46].
The sintered density in microwave-sintered austenitic stainless steel compacts was lower
than for the conventionally sintered counterpart, but microwave-sintered ferritic stainless
steel displayed the opposite trend.
Although grain growth was minimized with the use of microwave sintering in this study,
the mechanical properties were markedly reduced when compared to conventional sintering,
as shown in Table 4.12.
Figure 4.32 Elongation of MWS and CS Distaloy tensile bars (reproduced from [45] with kind
permission of Springer Science and Business Media)
Table 4.12 Effect of heating mode on the densification and mechanical properties of 316L and 434L
stainless steel sintered at 1400 C