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Originally Posted by The Reaper
Bill:
Can you comment on forged blades, versus stock removal, and the effect of the forging on the steel grain and crystalline structure?
TR
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Good question.
Historically the only way to refine a steel was by hand hammer forging (drawing out), re-stacking the steel and forge welding solid then forging it again, repeat until good results which if you made swords meant making swords that didn't break or bend easily.
This concept for steel refining was done on a much larger scale in the big steel mills into the early 1900's. English Shear Steel was a good example we know about in Oregon because this was how the plate for really big circular saw blades used in the sawmills was made.
Forging breaks up the large crystal/grain structures that resulted during the original melt of steel cooling into an ingot. Alloys tend to gather together during the initial cooling and form large crystals that would be too large and brittle to make into strong steel.
Now we are using steels that are highly refined during the steel making and forging (rolling into usable bar stock or sheet) processes. I seriously doubt any positive change in the steels grain structure can be accomplished by forging many modern tool steels.
Many of the top metallurgists in the country will back me up on this.
With some of the steels we use forging can easily cause more damage than good and the best the bladesmith can hope for is not ruin the steel when they forge the exotic (highly alloyed) steels. This is because the temperature range at which the steel can be forged is both high and narrow. Forging the steel outside these heat ranges can/will cause damage like the grain tearing apart resulting in cracks that will propagate during heat treat or use.
We are lucky to have many accomplished bladesmiths working in the world today and I don't want them hunting me down for any perceived slight to their craft. Keep working guys!
Industry will never duplicate the fine craft of forge welded patterns and making steel into blades like these guys do using the straight high carbon steels and I have the highest respect for the work being done.
This is what Yoshindo Yoshihara and his brother are doing, keeping a fine craft alive. They do amazing work at the forge.
Edited to continue:
Stock removal is the shop practice of knifemakers (myself included) of purchasing a particular type of steel, chosen for a range of best possible performance characteristics, which is roll forged into a specific shape and thickness of either bar or sheet.
Upon arrival in the knife shop the steel is then formed into a knife blade by cutting, abrasive grinding, machining, heat treating and finishing.
These steels have undergone considerable forging processes under tightly controlled temperature and atmosphere conditions in the mills before they arrive in the shop. Optimum heat treat and control of manufacturing process is the key to good results with these steels, not forging in the knife shop.