Frosty Posted July 5, 2015 Share Posted July 5, 2015 I've written about hard face anvil repairs a number of times recently and would rather not have to repeat the long ramble so soon. You can certainly preheat the anvil without damaging the heat treat of the face. I use charcoal briquettes in a cut down 55gl. drum without air holes near the bottom. This makes a long slow heat, two 25lb. bags of Kingsford and about 4 hours brought a 150lb. HB to 300f. You can buy "Tempil sticks" at the welding supply, they are markers like a crayon that melt or change color at specific temperatures. I marked the face of the anvil with a 350f. tempil stick stripe all the way across the face so you can monitor the edges and center of the face.The importance of preheating high carbon steel is to reduce the thermal shock of the arc and rapid cooling as heat is conducted to the rest of the face and body of the anvil. This thermal cycle shock zone is known as the HAZ Heat Affect Zone and is where most weld failures occur.Preheating the parent stock (anvil in this case) slows the chill (rate of cooling) and minimizes negative results in the HAZ.Read up on "Stringer Beads" they significantly reduce the HAZ which is very important when hard facing high carbon steel. Laying down big fat wide beads is NOT a good thing. Fast straight and narrow is much better but you only get to lay down two passes, one on top of another or you start running into the HAZ affecting the hard facing beads and this isn't a good thing. If it's going to need deeper repairs you need to use a build up rod and cap it with hard facing rod.There are books on hard facing I'll bet your local welding supply has them to give away, ours does.Post the pics, we'll opine away like always. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 5, 2015 Share Posted July 5, 2015 The preheat is so that the anvil doesn't self quench and cause cracking in the heat affected Zone. Is this bad? It can be very bad as you may have increased the size of the problem areas through such cracking. PLEASE STOP until you know what you are doing! The trick is to have the preheat below or at the drawing temperature and so not affect the hardness much. Do you have a method of accurately measuring the temperature of an anvil?Vulcans are made a different way. Do you need to butter the cast iron before adding to the steel face? You probably will need two different types of rod to weld up a Vulcan and the proper preheat of course Quote Link to comment Share on other sites More sharing options...
Ethan the blacksmith Posted July 5, 2015 Author Share Posted July 5, 2015 thank you everyone for the replies, and to frosty for the great explanation(and doing it again)!I have not observed any cracks, so I must be lucky. I know why; its frosty the lucky!(hahaha really bad joke)pics coming soon. I am very busy because the farm is going into hyper drive to get hay cut (because of bad drought) but I am trying hard to reply and upload all these pics! its great fun! Quote Link to comment Share on other sites More sharing options...
BIGGUNDOCTOR Posted July 5, 2015 Share Posted July 5, 2015 It may not show cracks, but an errant strike can cause the edge to chip off at the side of the weld bead. It is like air hardening a piece of steel. It is at critical temp, and the anvil mass cools it too quickly creating a very hard line at the edge of the weld. A post heating may be in order to temper the area welded to prevent cracking. I would run a torch along the welded are until I saw the colors start to run. Quote Link to comment Share on other sites More sharing options...
Ethan the blacksmith Posted July 5, 2015 Author Share Posted July 5, 2015 Thanks biggundoctor, will do! Quote Link to comment Share on other sites More sharing options...
BIGGUNDOCTOR Posted July 5, 2015 Share Posted July 5, 2015 Temp sticks will help take the guesswork out. They are at welding suppliers. Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 6, 2015 Share Posted July 6, 2015 Lucky so far, HAZ cracks usually don't show up right away. It's good to hear I have enough luck left to share around. We'll keep our fingers crossed.Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Ethan the blacksmith Posted July 21, 2015 Author Share Posted July 21, 2015 Finally have the pics. one is a Vulcan, the other, mystery! Quote Link to comment Share on other sites More sharing options...
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