Cast Iron pitting with high heat

[johnl]

I have noticed on cast iron surfaces that have been heated pretty well, they form craters on the surface. I have seen it on exhaust headers on cars where the timimg was wrong. I was wondering if this is a standard phenomenon and what action is occurring here to cause this?

thanks

John

 

[Gokul43201]

I think what's accelerating the corrosion to the exhaust header is the high temperatures. If you have a leak in the exhaust, you will end up trapping heat between the cylinder head and the exhaust header. This increased temperature raises diffusion rates and hence speeds up the rate of corrosion.