45Mn chemistry for Al refine

Try dissolving the casting (or a piece thereof) and then doing an analysis of the metals found, either by wet chemistry or spectral analysis, etc.

Dear wealdcn017,

The aluminum is added at end of steel making as a grain refiner. if the steel has been properly deoxidized before the addition of aluminum, the aluminum will not be overly consumed by oxygen in the melt and so get wasted by carry out in the slag.

The level of .02 wt% is about the minimum that is necessary to assure that the steel is an austenitic fine grained steel in most commercial processes. (DO NOT confuse with as rolled grainsize! I repeat, DO NOT confuse with as rolled grain size.)

Attempting to understand the basis for your question, it is very possible that your steel supplier does not have a technologically advanced caster, and so is unable to use Aluminum for grain refinement, they would probably be using either Niobium or Vanadium after silicon deoxidation to try to get fine grain. This is due to problems with reoxidation of aluminum cutting off at the tundish and molds if they do not have submerged nozzles or have intermittent problems with inert gas shrouding. These steels respond differently to heat treatment than do aluminum fine grained steels, in my experience.

The analysis of aluminum either by wet or optical emissions means is somewhat problematic as there are both an acid soluble and acid insoluble component. It has been over 20 years, I do not recall which was of most interest in our work for process control...

I have seen aluminum levels of .050-.080 wt % in certain ultr-high quality Japanese steels designed for extreme cold working applications. However meltshop process control and ladle metallurgy must be first class. Aluminates are not the nicest nonmetallic inclusion for a machine tool to encounter, due to their high hardness, so using more Al than needed to assure austenitic fine grain exacts an economic toll in poorer tool life and more expense for machining the forging into a final part, as well as an internally more 'dirty' casting.

Unlike in the biological realm, more is not necessarily better.

milo