welding/brazing steel to carbide

Terry,

Are you talking about the bead mandrel that the bead is formed on or a tool for working the bead. I've made the mandrels in the past for a few bead makers out of 309 TIG rod and they seem to work fine, the commercially supplied one I've seen look to be TIG rod also. Maybe for a mandrel TIG tungsten of if carbide rod then hold either in some sort of pin chuck with an extension for gripping away from the heat.

Commerical brazed-tip cutting tools use bronze brazing. I have some homemade ones that were silver brazed.

There are brazing alloys that are made specifically for brazing carbide cutting tips onto steel shanks. Handy & Harman/Lucas-Milhaupt's Easy-Flo 3 is one that's been around for decades, if you don't mind the cadmium. There may be newer ones. Watch the solidus temperatures if they're to be exposed to molten glass. Easy-Flo 3 is 1170 deg. F.

If you don't want to burn your hand, a section of stainless tube has less heat conductivity than solid steel...

So, what carbide is it? SiC, B4C, WC are all carbides, one would hope that it's a bit of tungsten carbide composite (cobalt metal is what the braze sticks to), but it doesn't hurt to ask. Even C2/C4 could make a difference.

there was a hi-temp braze or TIG filler that would work . Right now I have no idea what the operating temp is , but I do know that when I use glass as a cover flux for brass/bronze melts it's a very thick liquid at pouring temps .

I looked through that Hany and Harman list and I see one newer one made for carbide/steel has a solidus over 1600 deg. F. That ought to cover you.

I've TIG brazed tungsten carbide to steel and stainless steel with silicon bronze wire with some success. If heat resistance is more important than strength and impact resistance, and if you can use a generous fillet or vee joint, it might be worth a try. The silicon bronze wets the carbide pretty well, but will not flow into a butt joint like silver solder will.

I think you'll have to weld it, as brazing rod melts at 840C, bronze at 900C, and non-liquid glass works at 1,427-1,538C.

There is a glass blower and foundry in town which was open one First Friday (artsy shindig) for touring. Their utility bills are enormous and it's hot work, like smithing, only quieter and a tad more gentle. ;)

That was fun research. I was surprised that blowing tubes or hot glass holders weren't common online. The Glass Forge used what appeared to be something like 5/8 seamless tubing for blowing with some sort of larger end at the hot working side, maybe carbide.

The temperatures you mention of 1427C to 1538C are the sort of temperatures that are used to convert the glass batch, the raw ingredients, into molten glass, that is far higher than the working temperature of the glass even borosilicate. I make glass blowing irons from time to time and use 316 seamless tubing for the shanks and 310 for the heads. 310 and 309 are common for the heads, some spendy makes use inconel if you have the money. I have never heard of carbide used for the heads. Typical glass I blow whether soda lime or lead crystal is held at about 1100C for gathering and is worked at a lower temperature. The blowing irons are common online although they're not many makers, in the US you should find Steinert, Spiral Arts, and Nickelite to name a few.

Greetings Terry, I do some work for some glass blowers that gather glass onto sections of copper pipe that is in turn held in a steel bushing on the end of the blow pipe. The copper doesn't melt from the glass. I imagine the carbide part will never get as hot as the glass becuase it will probably be only piercing the glass, it won't be used to gather the glass. So a high temp silver solder, a "hard solder", would probably work fine. Eric

Right you are, which makes me wonder why the page said "non-liquid glass". Back to the draw...googling board.

Yeah, he was talking beads while I expanded on it to include blowing. Thanks for the correction.

It's not uncommon for technical information to be incorrect just watch any episode of "How it's Made" as an example. Often the artisans/workers may be very skilled at their job but not know much about the technical details involved in some of the processes and then get someone involved to take down those details who doesn't know about the process and it can be like Chinese whispers where what goes in one end is different to what comes out the other.

I suspect that stainless steel will work just fine. May not last forever, but would be much less expensive to make.

Dan