molybdenum

[purebreedcolt]

Hey new to the board and have a question. I bought a couple of what look like large hack saw blades at the flea mkt the other day. I know what they are used for but the blade is stamed with H.S. molybdenum. I looked it up on the net and found the element and all of that good stuff. The blade is harder than any file I have ever seen. I usually use a dremel tool to get my basic shape but that stuff ate through so many little cut off wheels it was horrable. I get it cut out finally and now need some advice on what to do now with it.

 

[Stacy E. Apelt - Bladesmith]

What you have is a High Speed tool steel power hack saw blade with molybdenum added to the alloy to make it tougher. It will be quite hard (after all, it is made to cut steel). It can be ground in the hardened state with fresh belts and constant dipping in water to maintain the hardness. It can be annealed and worked, then re-hardened, but these processes are way beyond a beginners scope (It will require a HT oven, ramping and holding and a high temperature soak before plate quenching.).
Stacy

 

[Nathan the Machinist]

Actually it is likely the same hardness as your files, but with a higher volume of carbides.

It sounds like you have a high speed steel power hacksaw blade. They make good precision knives (not rough use knives). They tend to be in the HRC 64-66 range, which is quite hard. Knives like this are best thin, so you have some grinding to do. Moly helps with hot hardness, so your knife will withstand a lot of heat during grinding. Try not to get it red hot while grinding. Wear a good particle mask, some of the dust can be toxic.

You'll probably fail when you try to put tang pin holes in it, so plan on roughing it up and epoxying your scales on without pins. Or spend a lot of time with a diamond burr...

Edit to add:

Molybdenum - (Mo) increases strength, hardness, hardenability and toughness, as well as creep resistance and strength at elevated temperatures. It improves machinability and resistance to corrosion, and it intensifies effects or other alloying elements. In hot-work steels, it increases re-hardness properties.

 

[mete]

And it forms very wear resistant carbides as in CPM154 !

 

[Frank Barron]

for pin holes do this. Take your dremel cut off wheel, not the easily broken ones, the ones that have fiberglass or reinforcing on them. Choose where you want your pins and start making a slot, stop when you have made an 1/8 cut through to the other side. Then make another slot at 90 degrees to the first one, do this so the slots line up, then take your burr and make your hole. It works on hardened steel.

Frank