I have a text book from ASM that is great, but definately overkill for the CWI examination. The book presents the information in such a way that it is "easily" understood. It is actually a Materials Science text book that covers metals and cerramics. It covers the basics and does a good job of covering iron and iron alloys and how the microstructure can transform from one phase to another by heating and cooling that is easily understood. That is one subject the other texts struggle to explain.
I like George Linnerts book. It goes into much more detail than the text book from ASM, but I found it more difficult to put all the pieces together.
I read the book from Lincoln and while it is OK, it isn't one that I would recommend to add to a professional library.
I would list the title of the book from ASM, but I would have to wade through a pile of books waist high and that might take a while.
Best regards - Al