I don't think the Met Eng meant that the steel and iron were homogenized, rather they have become more joined than "just stuck together."
DDA
I'm pretty sure that's what I was saying when I questioned the Met Engineer's use of the term "mono-metal". "Mono-metal" would certainly seem to imply homogenization. And I also said the following, which would indicate that they are more than "just stuck together."
Certainly, there is amalgamation and fusion within the weld joints.
I read several articles on Post Weld Heat Treatment which all suggest that there is more involved than simply playing a torch on the HAZ. It sounds as though doing some seat of the pants post annealing or heat treatment would be preferable to nothing at all. But some degree of control is necessary depending upon the alloys that have been welded, and the desired end result properties, ranging from full annealing to normalizing to stress relieving. Two of the factors are time and temperature which is why I questioned the possibility of affecting the brazing of the monobloc section. That could also be controlled with the use of heat sinks or heat control pastes. Here's a few articles to consider, but hardly all there is to know when the weld is subject to high pressures only inches from your face:
http://www.thefabricator.com/article/met...strengthened-sthttp://www.superheatfgh.com/heat-treatment/heat-treatment-applications/post-weld-heat-treatment/http://file.scirp.org/pdf/JMMCE20100600005_84007347.pdf
