DEERESMITH Posted June 29, 2008 Share Posted June 29, 2008 I was attempting to make a J-hook, like the tow truck drivers use. I used a 1" diameter stabilizer bar from a car. I had significant straightening to do, and then I forged it down to 1/2" thick. I got interrupted and let it sit overnight, and this morning I noticed the crack. Did I do something wrong or was it the metal that I used? Who can help? Quote Link to comment Share on other sites More sharing options...
S.Willis Posted June 29, 2008 Share Posted June 29, 2008 Its hard to tell, It looks like a stress crack. I have had sway bars crack from over heating and by hammer it to cold. Quote Link to comment Share on other sites More sharing options...
unkle spike Posted June 29, 2008 Share Posted June 29, 2008 My guess would be cold hammering, when working a piece, you have to keep the WHOLE piece heated. When you have an end hanging over the edge of the anvil that is cold, and you are hammering on a spot farther up the piece, the hangover will crack 9 out of 10 times, especially if it is thin. Keep the whole piece at working temperature while working on it. This is very true for pieces that are quenched during working. Todays metal is full of recycled content, and you encounter very different properties in the length of the bar of stock. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted June 29, 2008 Share Posted June 29, 2008 By any chance did you cool that in water ? that may have enough carbon to crack with a water dip. Quote Link to comment Share on other sites More sharing options...
Valentin Posted June 29, 2008 Share Posted June 29, 2008 Nice finger nails Genuine blacksmithing hands ... and regarding your question if u cooled the pieace in water ... i whould not be amazed but just from hammering it even cold it;s hard for me to belive that it cracked ... i do a lot of hammering cold and unless i bend the peace i can;t get it to crack. Quote Link to comment Share on other sites More sharing options...
DEERESMITH Posted June 29, 2008 Author Share Posted June 29, 2008 The fingernail belonges to my lovely wife. I did not quench in water. It was a lot of work straightening this sway bar. I still have the other half of the sway bar, but I hate to invest that much work again if it is going to crack again. I plan on making a large j hook to chain cars onto a car trailer. Is there a chance that the metal is at fault? Should I scrap this sway bar, and find something else? I don't think I can keep this entire piece at working temp, this is quite a chunk of iron. Let me know what you think. Quote Link to comment Share on other sites More sharing options...
nett Posted June 29, 2008 Share Posted June 29, 2008 You don't need the heat the whole thing, but you need to have it hot where you are hammering. I believe you got in a few licks on the steel below temperature, and that caused the cracks. WORK it HOT! Work it in a bright cherry or hotter and don't strike it below that temperature. Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted June 30, 2008 Share Posted June 30, 2008 It's likely that you forged that steel at too high a temperature. I've had similar results trying to learn to forge A2 steel. Some tool steel has a narrow forging range. If you can guess or find out what type of steel it is, Goggle for heat treating it and you will find the forging temperature range. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 30, 2008 Share Posted June 30, 2008 4 minutes to download the pictures, the joys of living in the country. I'm on the too hot side as well as it looks a bit crunchy to me. Note I sure wouldn't suggest you make things who's failure may result in injury until you have quite a bit of experience in smithing! Quote Link to comment Share on other sites More sharing options...
patrick Posted June 30, 2008 Share Posted June 30, 2008 I am also of the opinion that the crack is caused by working the steel too hot rather than too cold. It looks to me like the steel was at a near welding heat in an oxidizing environment in the area of the crack. I have done this myself on numerous occasions when I used to forge with coal. I now use gas exclusivly, though not for reasons of over heating, but I do forge very hot. In the gas forge, rather than buring, you get heavy layers of scale or melting if you get too hot. You can probably work this material in the range of 2200-2300 F as I doubt very much that is a high alloy tool steel. More likely, it is an alloy steel of moderate carbon content such as 4140. I do not think there is anything wrong with the steel. Just pay attention to your temperture and where in the fire you put the work. If using coal, do go too deep in the fire or you will be too close to the air blast which is very oxygen rich. Patrick Quote Link to comment Share on other sites More sharing options...
kevan Posted June 30, 2008 Share Posted June 30, 2008 Although I would not like to butt heads with some of the really knowledgeable members of this site, I am inclined towards the cold side. But then again I don`t suppose it really matters whether it was too hot or too cold, the fact of the matter is that it is now buggered and unusable. Kevan Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 30, 2008 Share Posted June 30, 2008 I have to agree with Thomas on this one. Not necessarily on the forging mistake but with NOT experimenting with home forged pieces where there's a chance of hurting someone. Experiment all you want but buy the hooks till you've mastered the material you're forging. Safety first in all things, especially where the public is concerned. Just visualize a Subaru full of kids in the landing zone if the pickup truck on the wrecker comes loose. Visuals like that keep me from taking risks with other people. Frosty Frosty Quote Link to comment Share on other sites More sharing options...
DEERESMITH Posted July 1, 2008 Author Share Posted July 1, 2008 Thanks for the insight guys. I did get the metal to near welding temp during one of the heats. Do you suppose that the damage was caused by getting the metal that hot, or by forging it while it was that hot. What I am asking is, could I have avoided the damage by letting the piece cool down a bit before hammering, or was the damage already done by the time I pulled it out of the forge. PS I already decided against attempting to use a home forged hook to chain down a car after this failure, however, I still feel the need to learn where I went wrong. Thanks to all who took time to post. Quote Link to comment Share on other sites More sharing options...
Mills Posted July 1, 2008 Share Posted July 1, 2008 Depends on the alloy, but yes i'd say when you got it to that hi heat, especially if stayed there any length of time, the damage was done and irreversible. Quote Link to comment Share on other sites More sharing options...
Golden_eagle Posted July 1, 2008 Share Posted July 1, 2008 I had the same thing happen to me.... i was trying to forge an old hammer head in to a 'hawk, I worked it to cold (mid-low red) and the whole thing fell apart... Quote Link to comment Share on other sites More sharing options...
Bentiron1946 Posted July 1, 2008 Share Posted July 1, 2008 I had problems forging a bunch of lug wrench/jack handles from cars that I got for ten cents a piece at a yard sale. I thought that they would make good chisels and punches but they all got cracks just sitting and cooling after forging. So I thought of using them as big rivets to hold pieces of a sculpture together and here too they just cracked to pieces as they cooled. I figured after this failure that they maybe had to have some special heat treatment to be useful. This could be your problem with your steel. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 1, 2008 Share Posted July 1, 2008 High alloy tool steels will crumble like cottage cheese at hot forging temps I did that once with some H13 I was making a slitter out of---it's a pain to work at lower temps and falls apart at higher ones. Some alloys have quite narrow forging ranges and so are hard to use by the blacksmith. Quote Link to comment Share on other sites More sharing options...
Golden_eagle Posted July 2, 2008 Share Posted July 2, 2008 Thanks for saying that before i got the H13 to make that X pean hammer out of... Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 2, 2008 Share Posted July 2, 2008 Thanks for saying that before i got the H13 to make that X pean hammer out of... You're making a cross pein from H-13? That's a pretty serious case of overkill isn't it? Or do you have a cheap or free source? I'm happy as can be to have old truck axle to use. Frosty Quote Link to comment Share on other sites More sharing options...
patrick Posted July 2, 2008 Share Posted July 2, 2008 Typically, at least with alloy steels, once you over heat the steel, the damage is done. With wrought iron you can sometimes correct an overheat piece through additional forging. The conclusion of a crack due to overheating is based on the appearance of the crack. All cracks are NOT created equal and an understanding of the characteristics of different cracks will help you determine their cause. In this case, the crack is jagged and fairly wide. Cracks that occur due to phase transformations (quench cracks, cracks that occur on cooling etc.) tend to be very straight and tight. This is not always the case, but in general is true. Patrick Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 2, 2008 Share Posted July 2, 2008 Patrick, are the tours of Scott Forge you give as a staff metallurgist as interesting as the one we went on to CSS when you were a college student? Weird thoughts about trying to get up that way early in the week before Quad-State starts... That piece and the crack looked "crunchy" to me and thus overheated those other types of cracks like to hide and jump out only during polishing up a knife blade. Thomas Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted July 2, 2008 Share Posted July 2, 2008 I'll bet there is a story behind the question.... Patrick, are the tours of Scott Forge you give as a staff metallurgist as interesting as the one we went on to CSS when you were a college student? Care to share? Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted July 3, 2008 Share Posted July 3, 2008 Went Patrick was still just a MatSci student he had gotten an in with a metallurgist at a local steel casting company---they did a lot of large castings for RR gear---and the Mid Ohio Blacksmiths got an invite for a tour. As they were using 3 phase arc furnaces to see a pour we would have to go in late at night as the electricity is cheaper then and that's when they melt. So around 10pm IIRC we gathered together and start trekking through a series of enormous old buildings, the company had been in the same spot for close to 150 years. The melt was awsome with the crashing sounds of multiple tons of scrap steel having arcs from 3 16" diameter graphite rods run through it. In the control room I was watching the meters and gulped a bit when I saw that one was marked in kilo-amps---a bit stronger than the milliamps I had worked with previously. Adding the alloying elements was interesting with them running the "wire" in as well as shovelling in piles of various "gravels". They did a series of pours and then we wandered through the "junk building" filled with all the stuff that accumulates in 150 years....it was so big and full of stuff that a train nut friend completely missed that ther was a switching loco *inside* the building with us. We saw their old forge, anvils and steam hammer once used for tooling purposes too; I nearly dehydrated from all the drooling I was doing! We got out of there around 2am.... Quote Link to comment Share on other sites More sharing options...
Ted T Posted July 3, 2008 Share Posted July 3, 2008 That piece and the crack looked "crunchy" to me and thus overheated those other types of cracks like to hide and jump out only during polishing up a knife blade. Thomas My vote would lean toward overheating :mad: Ted Quote Link to comment Share on other sites More sharing options...
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