Reference Books and pages

Bruno

Administrator
Staff member
I think I found an error.
Page 84, the column heading that reads MC should be VC I think, given that MC is not listed in table 8.1 and the steels that have a number listed in that column are Vanadium steels. @Mike Blue or @Victor Creazzi ?
 

Mike Blue

Member
It's possible. No legend for the column headings appears. Frankly, a number of his graphs/illustrations are out of order for that chapter. I'll send this question to Larrin.
 

Victor Creazzi

King of Bondo
Well, I finished the book a few days ago. My reaction is that this book far surpasses anything else I have read on all aspects of heat treating. It could be that everything that I've previously read and learned gave me the base to absorb so much of what this book offers though. The book gave weight to a lot of my own thoughts about what is actually happening at the microstructure level.

I think that I will re read the book again from page one.
 

Bruno

Administrator
Staff member
Hey @Mike Blue on page 125, there is an explanation of the eutectoid point moving to the left, in high alloy steels.
It explains why you need higher temperatures to dissolve the carbon in the austenite. On the face of it, that makes sense.

Then I thought back to Feb when I tried forging a piece of CPM154 at Charlie's. I experimented with various temperatures until I got too hot, and the steel just fell apart under my hammer into a spoonful of sand. You explained it's the carbide growth doing that, esp the chromium.

How does that work then? I get that carbides grow and chromium is aggressively binding the carbon. But if I raise the temperature enough, shouldn't the carbon dissolve into the austenite and make it malleable?
 

Mike Blue

Member
Each alloying element has it's own rate of grain growth and carbon acquisition. Chrome is very aggressive of all those and tends to form large nasty carbides that are more fracture prone than say vanadium which tends to form fine carbides and responds better to grain reduction cycles. Even with higher temperature the carbides remain stable as a lattice for growing rather than dissolving in some cases.

Try forging some 12C27 or it's near relatives. They are more forgiving than most stainless under the hammer. There is still an upper limit though.
 

Bruno

Administrator
Staff member
I had to chuckle about the remark that lack of vanadium carbides makes steels like 52100 easier to handsand.

If that is easier, i don't want to know about vanadis 8 handsanding. Thankfully i know someone who can do ht in argon environment so no sanding necessary after ht.
 

Bruno

Administrator
Staff member
You'll love it. It's a great book. And it's set up in such a way that you can look at chapters more or less in whatever order you prefer. They're pretty independent which is great once you want to go back for specific things.
 

Victor Creazzi

King of Bondo
How does that work then? I get that carbides grow and chromium is aggressively binding the carbon. But if I raise the temperature enough, shouldn't the carbon dissolve into the austenite and make it malleable?
Bruno,

On page 125 Figure 13.2 shows a graph @ 2000º F. At this temperature all of the cementite is dissolved, but as Cr is increased above 6%, more and more Cr2C3 is being formed.

It would be very informative, to me at least, if there were another graph with a fixed amount of Cr and C and the temperature was the variable on the X axis. 154CPM has 14% Cr so plenty of Cr to suck up Carbon. So a graph of a steel with 14% Cr and 1% C would match the 154CPM.
 
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Victor Creazzi

King of Bondo
Going back and reading the book a second time from page one is helping me greatly. Most of my confusion involves the high alloy steels that I don't work with or plan to, so I have the luxury of just pondering my questions academically. The longer that I think about this stuff the more I understand it, so anything that saves me time may actually be doing myself a disservice.
 
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Victor Creazzi

King of Bondo
Ultimately I think the answer to Bruno's question about forging 154 CPM resides on page 193 which shows 154CM very low on the forgeability list. Elsewhere he talks about the carbides in some of the high alloy steels remaining all the way up to, and sometimes beyond, the melting temperature.
 

32t

Member
First thoughts this book makes me question the ability of Wootz to make a good razor edge.
 

Bruno

Administrator
Staff member
First thoughts this book makes me question the ability of Wootz to make a good razor edge.
In what way?

Another question to add: if a feather razor blade is much, much sharper than a freshly honed straight razor, why does the straight razor give you a much smoother and more comfortable shave?
 

Mike Blue

Member
Large carbides would weaken it. This is why Howard and I keep banging the drum for carbide control via temperature control in the forge (staying below coarsening temperature), grain size reduction in the workup to the final quench heat treatment.
 

Bruno

Administrator
Staff member
Absolutely. Yiu have to consider that the cementite carbides are more like long strands of hair in wootz. A customer once sent me a microscope pic he made with uv light or so. And you could see countless tiny dots sticking out but they were really microscopic.

Chromium carbides otoh are like bearing balls. Very large and round. They can get so big they literally fall out of the steel matrix.

Those would indeed suck to have in an edge
 
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