Only thing I could suggest isa trying to create your own i.e. start with something similar and tweak it to suit. Start with a rough steel, darken it and play around with texture size.
The Cloud Library in Keyshot offers some Cast Iron materials.
I don't recall if that is supported in Keyshot 8, you may have to update to Keyshot 9 (installer is on Alibre downloads page for those with entitlement to Alibre Design Expert v21).
Here's a couple of settings that be close enough to get started. Make adjustments from those shown until you get the desired results. Just change the parts material to Metal and make adjustments from there. You can also try the Fractal texture which has a few more options. The Gray color is set to HSV 0%,0%,66%.