patrick

It would be extremely difficult to get 1/4 x 1 to make 1/2 square. As Thomas noted, there is no accounting for scale loss. Additionally, you will absolutly get buckling when working this section size on edge because the aspect ratio is 4:1. In industrial practice the maximum aspect ratio that can be easily worked on edge or upset is 3:1. This phenomena is independant of hammer or press size. So, you will get buckling of this cross section if you work it on edge. You can flatten that out if you work it on edge a little, then flatten a little than back up on edge etc. However, when you flatten out the buckle, you will get some lengthening. It cannot be avoided. Therefore, even if you had no loss to scale, you still wouldn't end up with a true 1/2" square.

When you weld steels together, regardless of composition, you have a few things going on. First, the welding procesess melts the two pieces being welded in addition to the filler metal. Therefore the weld region has a composion that is as mix of all three components. Next you have the heat affected zone (HAZ). The HAZ consists of metal which was so hot it was austenitized and metal which was hot, but not austenitized. The austenitized region can transform to untempered martensite or other structures depending on the grade and cooling rate. When you weld mild steel to mild steel you normally will find the weld is relatively soft because there is not enough carbon and alloying elements to result in a hardened structured on cooling. This can change if the mild steel has a bit of carbon or if the object is so large that it cools the weld very quickly. When you start welding higher carbon and alloy steels you must use pre and post heating techniques otherwise the HAZ will be so brittle that you will get cracks under the weld bead itself. If I were going to weld S7, I would first determine what tempering temperature was needed do get it into a relatively tough state. I'd heat to that temperature, weld, then re-heat to that temperature and cool very slowly. Then I'd fully austentize the component, cool as needed to achieve full hardness, then temper to the desired hardness.

The largest press Scot Forge has in operation now is 5500 ton. They have a joint venture on going in New Castle Pa (North American Forgemasters) that is installing a 10,100 ton press that will be able to handle ingots on the order of 200,000 lbs. That press should be up and running by the end of the year. Heating times for large ingots vary by size, but a 30" diameter ingot will take around 24 hours. Larger ingots can take twice or three times as long. The fuel is natural gas fired box style furnaces, some easily as large as a two car garage. The Scot Forge website was significantly overhauled earlier this year and now is by far the best in the industry. With nothing more than that website I could teach an entire class on industrial open die forging. By the way Thomas, yes I do have a bigger Bradley than the 300, a 500) and thought it is in the shop I don't have the motor hooked to it yet.

Look up murry carter. He forges in the Japanese style and I think he's running on of those hammers. Another option would be a yoder or pettingell style sheet metal hammer. If you can find one both Bradley and beadry made small hammers for the cuttlery industry. I know of two Bradley 15# strap hammers but they are both project hammers. There are probably more out there I've just never seen them.

Congratulations!! Can't wait to see what you make.

John Larson has been building the Iron Kiss hammers this way for more than a decade and it is a great way to make the anvil if the plates are solidly attached to each other.

I know this is a little off topic, but it is related. I've never seen that design of hammer. It looks like an inline treadle hammer with the foot treadle replaced by the air cylinder. Is it intended to be an air operated treadle hammer? Other than the shorter overall height, what advantages are their to this style of air cylinder placement as compared with the cylinder mounted directly above the ram? Thanks for enlightening me.

The type of coating under discussion here is very thin so there concernce not only about the wear resistance of the coating itself but also of the ability of the base material to support that coating. Since the base material hardness will be reduced by the coating process, its ability to support that coating will be reduced, but I can't say of a couple of HRC points lower hardness will be significant to the applicaiton. The original poster really needs to seek input from a technical representitive of the coating supplier or someone who specializes in tribology. There may be other ways to deal with his problem besides just increasing surface hardness.

Maurice, Once you have a good weld, then you need to polish to a pretty uniform finish and etch. The choice of etchant makes a huge differance. In the pictures you showed, it looks like some of the components were exposed to either chemical or heat blueing which is a little differnet than an etch. I suggest you take your work, polishing and expose it to temperatures around 500 F just to see if you can get the pattern to show up. You may also need to experiment with chemical etchants. A common one is ferric chloride, but I don't know how much contrast you'll get between mild steel and nickel with that etchant.

If you are planning to do a lot of repeated textures of constant depth, you might want to get a punch press rather than a hammer. These machines don't have quite the versatiity of a hammer since the stroke length is fixed and there is no flexiblity in the linkage, but, for very precise, repeated patterns, they are likely going to be more efficient than a hammer. For examples of work make with these types of tools visit sandersoniron.com.

T420 is forgable but quite stiff compared to carbon and low alloy steels. It is not generally used for blad cutting edges, but it can be used in the san mai technique in combination with a high carbon steel cutting edge to create a rather striking looking blade. I've seen this done with T416 and there is no reason T420 won't work. ESR-Electro Slag Remelt: This is a method in which an ingot cast in the conventional manner is remelted. The ingot becomes and electrode, much like a giant version of a stick electrode for welding. The ingot is placed into a water cooled copper mold and melted slowing from one end to the other. this can take many hours depending on the size of the starting ingot. The melted metal passed through a layer of slag which helps catch any bits of non-metallic inclusion material that remained from the inital ingot casting process. The other big advantage of the remelting process is that it results in a final product with much less chemical segregation than an ingot cast in the convential manner. There is a similar process which is conducted under vaccum but with out the slag called Vacuum Arc Remelting. Similar benefits, but this process is particulary useful for removing dissoved gasses.

You can determine the theoretical width you'd get assuming no material loss to scale and no elongation by caculating the cross sectional area of the starting stock and the thickness you want to reach. If that width is not as wide as you want you will have to upset. If the math shows you can get to the desired width, then you need to spread the metal using a fuller or cross peen type hammer. A flat faced hammer will move the metal in all directions, resulting in significant elongation. A narrow peen or fuller can be used like a rolling pin to direct the metal where you want it to go.

Manganese sulfide inclusions come from steel making making (liquid state) so you won't be able to add more of them by forging. You can add oxide type inclusions by forge welding sheets or plates in a way that does not completely seal them from the atmosphere during heating. However, that is not a controlled method and it may not give you the type of inclusions you need to conduct your test. if you want a lot of manganese sulfides, switch from 1018 to 1117. This is a similar grade but has intenstionally elevated levels of managnese and sulfur to make lots of sulfides which aid in machining.

Actually most of the high carbon steels with some alloy content, such as 52100, will also form the large carbides Quenchcrack mentioned. These carbides are usually distrubuted along the grain boundaries and provide a ready path for crack propigation. Therefore, we do not use a conventional anneal with these grades. Rather, when a soft, machinable structure is required a spheroidize anneal is used. This multi step heating/cool cycle prevents the formation of the grain boundary carbide and instead promotes the formation of finely distrubuted carbide spheres. The easy crack path is avoided while still maitaining a workable structure. Also, since the carbon is now more uniformly distributed throughout the microstrucutre, the austentizing cycle prior to quench is more effective and can be shorter than when dealing with conventionally annealed versions of these materials.

The eutectoid composition on the iron/carbon phase diagram is 0.77%. Hypo eutectoid compositions have less that that and Hyper eutetoid have more. I have audited the ArcelorMittal facility in Steelton, PA becuase that is one of the few shops inthe company that still make the ingots we need for forging. They do make rail their and what I found most interesting is that they have to achieve a hardness in excess of 40 HRC while still keeping the microstructure pearlitic. No martensite or bainite allowed. So, while the compostion of rail is perfectly fine for blades the microstruce is not.

Sensitized vs. non-senstized will make no difference during forging. This has to do with corrosion resistance. The sensitized condition is not as corrosion resistant as non-sensitized material. Maximum corrosion resistance is typically achieved in this and most other austentic grades by heating to 1900 F or higher and rapidly cooling to prevent chrome from reacting with carbon. T-347 and T-321 are stabalized versions in which either titanium or niobium is added to grab carbon before the chrome has a chance to reacte with it. If chrom combines with carbon, you get a reduction in the corrosion resistance. But at forging temperatures none of this matters since carbon will be dissoved in the austenite.You should be able to completely restore maximum corrosion resistance after forging by solution annealing. The nice thing about T-347 and T-321 is that they are less suseceptible to sensitization than are the regular austenitcs. This make them easier to fabricate, since often welded structures can't be solution annealed. Patrick Nowak (Metallurgist at Scot Forge for the past 12 years)

I am surprised you didn't find the slack belt clutch to give excellent control. That's the system used on Bradleys and a few other commercial hammers and they have excellent control.

If you do a you tube search for 300#Bradley you can find a couple of videos of me forging mokume with it. A lot of what I make gets forged to a final thickness of 0.220" so you actually do need a fair amount of power when making wide flat bar.

Also, there are some in line designs that are very compact which is nice for small shops.

The billets im working with are bonded for two to three hours. Copper red brass and nickel silver. No rolling mill. All done with a 300#Bradley using stop blocks.I'll have to review the nichols video to confirm his technique.

Frosty- I think you got most of the diffusion stuff right. Diffusion rate is temperature dependent. The higher the temperature the faster the diffusion rate. As you already noted, solid state welding can occur with little or no diffusion, as in the case of galling of threaded components. Once the initial atomic bonds have been made across the interface you have solid state weld. That usually will strengthen with time at temperature as diffusion occurs across the interface. However, there are some systems which will form intermetallic compounds which could weaken the interface. In those case, you may want to avoid diffusion. I should point out that in Chad Nichols video on mokume he does use a fairly short time in a gas furnace, less than 30 minutes I think. His furnace temperature was very close to the melting point of copper and his first squeeze on his billet, while still clamped between plates, was done in a hydraulic press. Most of his forging of mokume was done with his presses, which I found to be terribly slow for this kind of work. Attached is a picture of what I forged Sunday afternoon. This is the product of 15 billets originally 2x2x6. about 8 solid hours of twisting and forging.

When I was a student I used to go to Research Alloys in Columbus, but that was 15 years ago. Don't know if it even exists by that name anymore. The other place I went a lot was the Welding Engineering department at Ohio State. That was before the moved to the new facility on the east side of the Olentangy River. I'd still check in with them. Ask to speak to Larry Heckadorn. Another place I went was First Street Recycling in Dayton.

Frosty- If you don't have a copy of Solid Phase Welding by Tylecote I highly recommend it. In the case of solid state bonded mokume, you do actually need a fair amount of time to get a good bond. This is because you don't have intimate contact across the interface to start even when clamped in the torque plates. The high points of the interface will bond first, but then you have to rely on diffusion for that interface to grow across the entire surface. This is some what similar to what happens when you sinter metal powder.Plus, if you do have any contamination on the surface, the diffusion process will help integrate that into the bond. Diffusion is a slow process, especially for metals with large atomic radius. (Side note, look up Fick's Law and use it to calculate the time needed to develop a case depth of 0.050" in carbon steel at 1700 F). I bring that up because carbon is one of the smallest atoms commonly used in diffusion processes. Copper, Nickel and silver are all much larger and will take much longer to diffuse than carbon. As long as you have not developed a liquid phase at the interface, you are dealing with diffusion bonding. To illustrate the strength of mokume made using the diffusion bonding process I described earlier, I did a little experiment. I trimmed a 3/8" thick slice off of a 1.125" octagon bar I forged this afternoon. (Starting cross section was 2" square.) I forged that slice by upsetting perpendicular to the plane of the bonds and got the little sheet shown in the photo. The thickness varied from 0.020" to 0.050" (I don't have a rolling mill to make it uniform and was in the middle of some other work so I didn't try to take it any further). As you can see, the bonds help up fine. There was a little bit of separation near the edges, but nothing severe.

For the copper silver billet noted above, you will get a liquid phase, just not with solder. The copper silver forms a eutectic and that does liquify unless you keep very close control on the temp. For the diffusion bonding method, hold times are usually about 2 hours for a billet 2 inches square. Hold temperature depends on the materials in the billets, but you want to get about 25 F below the melting point of the metal with the lowest melting point in the stack. The billets I've been working are either copper/nickel silver or copper/red brass/nickel silver. As to using a gas forge, yes you can but uniformity of temperature can be very difficult to achieve in gas which means you have to frequently flip and rotate the billet. Chad Nichols shows this method in his video on making mokume. If you want try the gas approach I strongly recommend putting some thermocouples in your forge so you know exactly what is happening. I did that recently with mine (for forging purposes) and it has been very helpful.

I have forged several thousand pounds of copper based mokume billets, all made with the diffusion bonding method with no additional solder. As long as the surfaces are kept extra super clean, you get a fantastic weld. I have no trouble doing agressive forging, twisting or upsetting with these billets. If you are trying to run a lot of pieces with predicable results every time this is a great method to use. It can be made very simple by the use of an electric kiln with good temperature control.