Hardening steel

[TechnicAl]

The prices 4" wide, I forgot the mug. Yeah I have some offcuts I could play with, I can get a hardness test done if I can find some ware local. How should I harden the test pice?

Get a hardness done on the piece. Then heat treat it as you describe.
I would use the 400 temper........its surprising how much softer another 50 degrees make.......550 and theres every chance its softer than what you started with.
I used to have the tempering curves but someone borrowed them and I havent got them back.......but they are quite steep if my memory serves me well.

 

[Richard.]

52-54 HRC is hard.

 

[Spark plug]

52-54 HRC is hard.

I haven quite got my head round the hardness scales it takeing me back to collage. What would you compare it too.

 

[Spark plug]

Some more pics:

 

[TechnicAl]

Oh right..........they are smaller than I imagined...........thats good

 

[TechnicAl]

I haven quite got my head round the hardness scales it takeing me back to collage. What would you compare it too.

Around 65 is the maximum you can get from a martensitic structure............higher hardness is usually carbide or some other
Mild steel will be less than 20

 

[Richard.]

I haven quite got my head round the hardness scales it takeing me back to collage. What would you compare it too.

550-600 vickers. It's lower than your average carbide tool steel (58-62HRC) but it's still very hard.
Mild steel is around 150 vickers if that gives you a better idea.

 

[Wedg1e]

Erm... I may have access to the sort of kit necessary to test hardness. I'm in Stockton, will check tomorrow. Could be either an Equotip or a Microdur, depends on what's in. Would take seconds, literally.
One technique drops a ball from a known height and measures the electrical signal created as the ball rebounds through a magnetic field; the other tries to drive a diamond stylus into the surface and measures the resistance to the force being applied. Either way you end up with a 1mm or so impact mark so if it's critical then it'd have to be done away from any important surface (which in the case of a used rail might give a false indication).
Did I mention we also have x-ray fluoroscopy (PMI)...

 

[Spark plug]

Erm... I may have access to the sort of kit necessary to test hardness. I'm in Stockton, will check tomorrow. Could be either an Equotip or a Microdur, depends on what's in. Would take seconds, literally.
One technique drops a ball from a known height and measures the electrical signal created as the ball rebounds through a magnetic field; the other tries to drive a diamond stylus into the surface and measures the resistance to the force being applied. Either way you end up with a 1mm or so impact mark so if it's critical then it'd have to be done away from any important surface (which in the case of a used rail might give a false indication).
Did I mention we also have x-ray fluoroscopy (PMI)...

That would be very helpful if you could and very mutch appreciated.

 

[TechnicAl]

Erm... I may have access to the sort of kit necessary to test hardness. I'm in Stockton, will check tomorrow. Could be either an Equotip or a Microdur, depends on what's in. Would take seconds, literally.
One technique drops a ball from a known height and measures the electrical signal created as the ball rebounds through a magnetic field; the other tries to drive a diamond stylus into the surface and measures the resistance to the force being applied. Either way you end up with a 1mm or so impact mark so if it's critical then it'd have to be done away from any important surface (which in the case of a used rail might give a false indication).
Did I mention we also have x-ray fluoroscopy (PMI)...

Personally I prefer the diamond..........never trusted the bouncing ball job (its much more sophisticated these days)

 

[Richard.]

We have a portable hardness tester which is surprisingly good and very well calibrated. It fires a very hard Spring loaded ball at the Sample area and measures the resistance. Then it gives you a digital readout in the scale you select. I've also had decent results with the old shear type where you actually measure the size of the dent through a magnifying eye peace with a scale and the chart supplied will give you your hardness value based on the dent width. (A little more skill and accuracy required with those) like most tests it's only as good as the surface you test it on. Milling/surface grinding a flat on the top and ensure its well secured underneath will make all the difference to the results. I've seen it used enough times on rough bumpy surfaces on wobbly samples and the results are waaaay off what you should be getting.

 

[hotrodder]

This set of dies will be for drawing steel down and as such I need to maintain the smoth radius that's been machine to the top. They won't be used every day but they could see some high point loads especially if forgoing other high carbon steels.

Gotcha

Looking at similar commercially available dies they are hardened to 52-54 Rockwell C. I'm not sure how this compares to say a hammer face or a punch die.

52-54 HRC is around the middle - upper range usual for hammers... https://www.google.co.uk/search?biw=1271&bih=668&q=hammer+face+45+-+60+hrc&oq=hammer+face+45+-+60+hrc Somewhere on the internet there's probably a list giving the usual hardness of things like files, hammers, chisels etc. A quick look didn't find anything but this came up instead http://www.auto-met.com/fowler/pdf/467.pdf if you can't take Wedg1e up on his kind offer. Chronos sell them cheaply, no idea if they (or at least cheapnese versions) are an utter waste of money though
One of the links in post #2 includes hardness numbers for a few flavours of rail, they're using a different scale and but they are various conversion charts about to translate Brinel this to Rockwell that and Vickers something else. Obviously less useful than getting an actual hardness measurement done as there's a fairly large range, the top surface of used rail is gonna be harder and obviously you've reshaped that area anyway

 

[Wedg1e]

That would be very helpful if you could and very mutch appreciated.

Scuppered at the moment as it's out on loan to a foundry in Billingham as we have theirs in for repair!
Give me a few days (if you can wait that long...)

 

[Spark plug]

Get a hardness done on the piece. Then heat treat it as you describe.
I would use the 400 temper........its surprising how much softer another 50 degrees make.......550 and theres every chance its softer than what you started with.
I used to have the tempering curves but someone borrowed them and I havent got them back.......but they are quite steep if my memory serves me well.

Just make img sure I'm on the right lines, I need to test the pice as is before heat treating, then I can use the results to better judge the treatment process?

Scuppered at the moment as it's out on loan to a foundry in Billingham as we have theirs in for repair!
Give me a few days (if you can wait that long...)

No I'm not in a big hurry I still need to make the holder for the top die anyway. I just appreciate the help.

 

[Spark plug]

Just thinking ahead again. What is the best method for measuring the temprature?

I have a K type digital thermocouple that is speked to 1350 deg C would this be suitable? If so do I need to measure the ambiant temp within the forge or the actual temprature of the item.

 

[Richard.]

Temple sticks. Best way forward IMHO.

 

[Richard.]

Just thinking ahead again. What is the best method for measuring the temprature?

I have a K type digital thermocouple that is speked to 1350 deg C would this be suitable? If so do I need to measure the ambiant temp within the forge or the actual temprature of the item.

Always measure the temp on the item your heating.* Simply scratch the stick across it. If it melts go next step higher until you reach a stick that doesn't melt this way you know for sure the temp range it's in. * It's only when measuring inter pass temps in welding when you don't scratch on the welded area but to one side on the parent. In your case measure the temp on the item.

 

[Spark plug]

Got a bit more done, I've painted the plate witch holds the lower tool. I've machined the top tool holder, that still needs a bit of paint.

I need to machine some T nuts to bolt the baseplate down, but still not sorted with the hardening.

 

[Screwdriver]

Looks interesting. Are you hot or cold forging with that? And what's it for?

S.

 

[Spark plug]

These dies are for hot forgeing, for drawing the steel down in the same manner as hitting the workpiece over the bick of the anvil.