Bending a bucket cutting edge.

[Walker1]

I need to replace the cutting edge on the bucket of my Case 530. The original was a 1/2"x 3" single bevel, weld on cutting edge. I hunk 3" is a little too skinny, and 1/2" is a little too thin. I am hoping to find a 5/8"x4"or5" edge to use. The original has bent up sides, which I like, but don't like the price and they seem to be not available in bigger dimensions.
I took a scrap piece of cutting edge and bent one side hot by clamping the end to the table and bending a 90. It is a bit too broad of a curve. After bending, I quenched it. I then heated the other end and bent it in my ironworker (wont bend cold). The bend radius is good. I let this one just sit and cool. I am curious which one will retain more of its abrasion resistant qualities. On the second bend I put a firebrick on the dye to see how well I could restraint the heat from creeping down the bar and annealing it. It did pretty well, so I will likely do that to keep the heat is a fairly small area.
Is anyone aware of the thermal properties of AR, and how to best get them back after heating. I can't seem to find anything concrete on the net.

Thanks,

 

[Ed of all trades]

There is a good chance that the one you quenched will break, depending on how hot it was when you quenched it. Knives that have been heated and quenched have been known to shatter when dropped. Ed

 

[Walker1]

Well, using my extremely scientific method I tested my results. I file tested the different spots and found that the file skips over easily in the center. The side I et cool was Rey soft, probably approaching mild steel hardness. The side I quenched was nearly as hard as the center. The spot that I kept the fire brick on in the forge, which was not quenched very quickly changed from hard to soft. I also did a brittleness test by beating on the quenched end with a big hammer (10# sledge) it didn't shatter, so I assume that once being welded to the bucket floor and sides it should be fine.
With those results I think I will brick off everything except a section about 3" wide and quench it after bending. Should worse come to worse and the bent area wear quicker than the rest, then I can add some hard facing.

 

[Ed of all trades]

Sounds like you have the know how to do a good job with it, and sounds like you are on the right track. Ed

 

[Renze]

When the edge is weldable, its low carbon steel like Borium 27 or Hardox 500 or a US equivalent. As a rule, if its weldable it will not become brittle when quenching it.

 

[Creamer]

Still I would temper it slightly. It all depends on how hot you got it to start with. I am assuming you took it all the way into the red zone which will affect the heat treat characteristics. I would take it into the red zone and form it as needed and then quench it in water which will make it hard and it may have a brittlizing effect. Then temper it it by reheating up into the blue-purple range but not into the red and letting it air cool and maybe even applying a little heat on the way down or insulating it a little to slow the cool down. this will allow the various consituents to rearrange themselves and not be so brittle but retain most of the hardness.

 

[Egon]

If the upturned edge is for the bucket sides just weld some cutting edge on the side.

 

[Walker1]

If the upturned edge is for the bucket sides just weld some cutting edge on the side.

I am a glutton for punishment. Plus I always feel that if somebody makes them, why can't I? I realized they likely bend them pre heat treatment though. On my last one I just left the original sides on there and welded a new bottom edge on.

 

[Raspy]

Still I would temper it slightly. It all depends on how hot you got it to start with. I am assuming you took it all the way into the red zone which will affect the heat treat characteristics. I would take it into the red zone and form it as needed and then quench it in water which will make it hard and it may have a brittlizing effect. Then temper it it by reheating up into the blue-purple range but not into the red and letting it air cool and maybe even applying a little heat on the way down or insulating it a little to slow the cool down. this will allow the various consituents to rearrange themselves and not be so brittle but retain most of the hardness.

Or couldn't a guy just heat it to red and quench in oil? This is a slower quench that toughens the metal, but avoids brittleness. I've done it a number of times and had excellent results.

 

[Creamer]

Quenching in oil has a couple of drawbacks - not as hard so poorer wear characteristics and not everybody has enough oil just hanging around to quench a whole edge in.