A petrochemical company experiences premature thermal fatigue failure of
the casting moulds used in catalyst production. The aim of the project was
to find an alternative alloy that would outperform the current low-alloy
cast steel used for the moulds. Based on their thermo-fatigue properties,
3CR12 ferritic stainless steel and H11 tool steel were chosen for testing
and comparison with the currently used BS3100 B7 cast steel. Samples of
each material were subjected to temperature cycling in a Gleeble 1500TM
thermo-mechanical processing simulator, followed by surface analyses.
The main parameters derived from the test work were the total true strain,
the hot strength of the materials, and the number of cycles to failure.
Additionally, the coefficient of thermal expansion for each material was
measured using a Bähr dilatometer. H11 tool steel yielded the best
performance by way of having the fewest surface cracks, the lowest total
true strain per cycle, the most cycles to failure, the highest hot strength,
and the lowest coefficient of thermal expansion.
Paper written on project work carried out in partial fulfilment of B. Eng.