Abstract: Thermo-mechanical processing with various processing parameters was applied to 0.2%C-0.6%Mn-2S%i-0.8%Cr low alloyed high strength steel. The aim of the processing was to achieve the microstructures typical for transformation induced plasticity (TRIP) steels. Thermo-mechanical processing used in this work incorporated two or three deformation steps. The deformations were in all the cases carried out during the cooling from soaking temperatures to various bainite hold temperatures. In this way, 4-10% of retained austenite were retained in the final microstructures, consisting further of ferrite, bainite, martensite and pearlite. The complex character of TRIP steel microstructure is responsible for its good strength and ductility. The strengths achieved in this work were in the range of 740 MPa – 836 MPa with ductility A5mm of 31-41%.
Abstract: This paper aims to study the effect of cold work
condition on the microstructure of Cu-1.5wt%Ti, and Cu-3.5wt%Ti
and hence mechanical properties. The samples under investigation
were machined, and solution heat treated. X-ray diffraction technique
is used to identify the different phases present after cold deformation
by compression and also different heat treatment and also measuring
the relative quantities of phases present. The metallographic
examination is used to study the microstructure of the samples. The
hardness measurements were used to indicate the change in
mechanical properties. The results are compared with the mechanical
properties obtained by previous workers. Experiments on cold
compression followed by aging of Cu-Ti alloys have indicated that
the most efficient hardening of the material results from continuous
precipitation of very fine particles within the matrix. These particles
were reported to be β`-type, Cu4Ti phase. The β`-β transformation
and particles coarsening within the matrix as well as long grain
boundaries were responsible for the overaging of Cu-1.5wt%Ti and
Cu-3.5wt%Ti alloys. It is well known that plate-like particles are β –
type, Cu3Ti phase. Discontinuous precipitation was found to start at
the grain boundaries and expand into grain interior. At the higher
aging temperature, a classic Widmanstätten morphology forms giving
rise to a coarse microstructure comprised of α and the equilibrium
phase β. Those results were confirmed by X-ray analysis, which
found that a few percent of Cu3Ti, β precipitates are formed during
aging at high temperature for long time for both Cu- Ti alloys (i.e.
Cu-1.5wt%Ti and Cu-3.5wt%Ti).
Abstract: The present study was carried out to investigate the
effect of alloying elements and thermo-mechanical treatment (TMT)
i.e. hot rolling and forging with different reduction ratios on the
hardness (HV) and impact toughness (J) of heat-treated low alloy
steels. An understanding of the combined effect of TMT and alloying
elements and by measuring hardness, impact toughness, resulting
from different heat treatment following TMT of the low alloy steels,
it is possible to determine which conditions yielded optimum
mechanical properties and high strength to weight ratio.
Experimental Correlations between hot work reduction ratio,
hardness and impact toughness for thermo-mechanically heat treated
low alloy steels are analyzed quantitatively, and both regression and
mathematical hardness and impact toughness models are developed.