Forging Tool Steel

Working with Tool Steel

When forging a high carbon or tool steel it is important to know the specific requirements of each type of steel.
Following the information supplied by the mill or steel distributor should help reduce problems.

1) Plan your forging process carefully to minimize the number of heats required. Each time that you heat the steel you lose a bit of carbon and decrease the usefulness of the steel.
2) Most tool steels must be allowed be heated slowly to the forging heat. This slow climb in temperature is generally referred to as “soaking”. In the Forgemaster TM forge soaking is easily accomplished. Bring the forge up to a strong heat (run the forge at 10-12 psi for about 5 minutes), place the tool steel into the heating chamber and heat the steel for about 30-40 seconds. Shut the forge off and leave the door closed, allowing the steel to soak up the heat of the forge without the added oxidation of the forge blast. When the steel becomes the same color as the heated forge re-ignite the forge and raise the steel to forging temperatures (usually between 1850 and 2000 degrees F).
3) Always forge the steel within the recommended heat range. Never forge tool steel at a heat below orange. Never heat tool steel above a bright lemon. Forging above or below the proper heat range may stress the steel and render it unusable.
4) Many tool steels require a “normalizing” following forging. Normalizing means that you bring the steel back to the forging temperature, and allow it to cool slowly at room temperature. NOTE:Air hardening steels cannot be normalized in this manner.

Carbon Steel Guide for Blacksmithing

AISI #Carbon contentTypical ApplicationsForging Heat RangeHeat Treating Method
O-1.90Taps, punches, dies1850-1950 F. Stop at 1500. Normalize.Oil quench
A-21.00Trimming Dies, Shear Blades, Punch Plates2000-2050 F. Stop at 1700 F. Normalize.Oil quench
D-21.55Blanking Dies, Bushings, Shear Blades, Burnishing Tools1950-2050 F. Stop at 1700 F. Do not Normalize.Oil quench
S-1.50Heading Dies, Hot forming dies, Chisels2000-2100 F. Stop at 1660 F. Normalize.Oil quench preferred, but larger sections may be water quenched
S-3.40-.50Chain link, Riveting, Caulking dies, Heading dies, Stone points, Trip Hammer Anvils1700-1900 F. Stop at 1500 F. NormalizeOil quench
S-7.45-.55Bending Dies, Hot Heading tools, Rivet Sets and Busters, PunchesPreheat 1200-1300 F. Raise to 2000-2050 F. Stop at 1700 F. Do Not Normalize.Air quench
4140.36-.50Jigs, molds, fixtures, holding blocksPreheat 1200-1300 F. Raise to 1850-2050 F. Stop at 1500 F. Normalize.Oil quench
6150.43-.48Gears, Shafts, Spindles1950-2250 F. Stop at 1800 F. Normalize.Oil quench

Forge Welding

Forge welding has often been a confidence shaker for blacksmiths. While it does take some thought and planning, it is not the mystical union of metals you may have thought. There are several key factors in forge welding in the Forgemaster TM.

Forge & Anvil Preparation
1) Pre-heat the forge by increasing the regulator pressure to 12-15 psi. Allow the forge to run at this pressure while you are forging the scarf and preparing the steel for the weld.

2) Pre-heat the anvil by forging or by heating a large piece of steel and laying it on the anvil face. A cold anvil will rapidly draw the heat away from the weld, which will result in a failure to weld.

If pre-heating the anvil is not practical, you might try placing a small amount of welding flux on the face of the anvil at the spot where you will weld. The flux will serve as a brief insulator to assist your weld.

Steel Preparation
3) Proper shaping of the areas to be welded (scarf) is an important part of proper forge welding.

A finely feathered edge will hide the weld, avoiding “cold shuts”.

Be sure to lap the weld area so that there is sufficient material to hammer together and avoid a thin weld area.

Welding Heat & Flux
4) After the scarf is prepared place the material into the Forgemaster TM forge, with the area to be welded under one of the burners. Avoid allowing the weld area to lay directly on the brick hearth, as the heat must be allowed to “wrap” around the weld area.

Avoid resting the weld area on the brick hearth.

Setting the weld area directly under the flame with space beneath the weld are and the brick will make forge welding easier.

5) Bring the material up to welding temperature. If the forge has been operating at 12-15 p.s.i. while you were preparing the scarf, you should have welding heat in about 30 seconds. When welding heat is reached remove the steel from the fire and quickly brush the weld area with a heavy steel brush to remove excess scale. Quickly apply flux and return to the fire. This sequence should be accomplished in just a few seconds to avoid losing much heat. The longer the flux is in the fire the less effective it is.

Butcher Block brushes work well for quickly removing scale build up.

There are several good forge welding fluxes. Sure Weld and Stable Weld are two that work well.

6) After the flux is applied return the steel to the forge and regain welding heat. When welding heat is reached remove the steel from the fire and hammer the two pieces together with quick hammer blows. Your finished weld should be clean and have no weld lines.

Flat view of scarf area after welding

Edge view of scarf area before welding

Edge view of scarf area after welding


Aluminum Shoes

General Information

Forging aluminum used to be a problem for even experienced blacksmiths. Forge welding aluminum was not even considered. Following these steps in a Forgemaster TM forging furnace will enable even novice blacksmiths to be quite proficient at forging aluminum.

1) Reduce the heat in the forge by lowering the regulator pressure to 6-7 psi. If your Forgemaster TM forge is equipped with a door, work with the door open. These two actions will lower the temperature inside the forge. Most aluminum and aluminum alloys used for hand forging becomes malleable at 700-900 degrees Fahrenheit, and melts at about 1400.

2) It will not take long for aluminum to reach forging heat. Several methods can be employed to determine the proper heat:

a. mark the aluminum with an 800 degree “temple stick” and watch for the mark to melt.
b. remove the aluminum from the forge and drag it across the face of your anvil. If it is at forging temperature it will seem tacky and resist dragging.
c. remove the aluminum from the forge and touch it to a piece of wood or newspaper. If it lightly scorches either of these it is ready to work.

3) As soon as the piece reaches the desired forging temperature you may begin to work. The aluminum will probably not need to be reheated, as it will remain in a soft state. Should you feel the need to reheat the piece be careful, a few seconds too long in the fire will result in an unusable piece of aluminum.

4) If the aluminum breaks and crumbles when you strike it with your hammer it indicates that it was overheated.

Forge Welding Aluminum

The technique used to forge weld aluminum is considerably different than steel or iron welding. The forge temperature should be kept at a low, soft heat (5-7 psi.). Use a flux core aluminum rod for this procedure. 1/8″ diameter Cor-Al aluminum welding rod manufactured by Welco is excellent. The following series of photographic steps will guide you through the process of forge welding an aluminum barshoe.

1) Heat the shoe (as described in the section above) to a forging heat.

2) Turn the heels as you normally do to forge a steel bar shoe. These photos shows how to forge a crisp corner on the barshoe after you turn the heel.

Side and Front View

3) After turning and forging each heel of the shoe, scarf the ends as you would for any forge weld. The overlap does not need to be as thick as for a steel bar shoe since most of the forging of an aluminum barshoe takes place before the weld is made.

4) Photos #3 & #4 show the correct taper and overlap of the scarf area to will be welded.

End and Top View

5) Now for the delicate part of the process. Photos #5 & #6 show the farrier melting a small piece of the Cor-Al welding rod onto the area of the scarf. This piece will serve as a reference point for determining when the area is hot enough to weld.

6) Watch the small piece of aluminum welding rod carefully. It will become bright and then begin to flow. As soon as it melts begin applying the welding rod, so that the entire weld area is liquid looking. Pull the shoe out of the fire as you apply the rod. When the rod stops flowing into the weld area you may return the shoe to the fire if you feel the need to add more filler rod. Be careful of too much heat. The reference is the Cor-Al rod (when it becomes liquid and flowing, remove the shoe from the fire. When it becomes solid and no longer liquid you may wish to apply a little more heat.)

7) After you have enough filler rod and the aluminum is welded, allow the material to cool. If you are making a pair of bar shoes, place the first shoe to the side while you weld the second. Here is what the weld should look like just after you finish welding.

Not a very pretty sight. However, after it cools down, brush the blackened area of the weld with a wire brush. You may then forge the weld without fear of separation. This will allow you to fashion the bar to suit your requirements. You will not need to heat the shoe again in order to forge it. Aluminum will remain malleable even after a long period of time.

The finished product will be similar to this:


Pritchel Repair

Of all the tools that a farrier uses, the pritchel probably takes the most abuse. Not because the farrier is abusive to it, but because of the work it must perform. Due to the extreme task it performs, the farrier must regularly attend to the condition of the pritchel.

The following steps will show the repair or dressing of the pritchel. REMEMBER that most pritchels are forged from tool steel (generally S-7 or H-13 see the tool steel guide for forging specifications). Forging heats are critical to the well being of the tool.

The heat of the horseshoe and the relatively small tip on the pritchel results a “mushrooming” effect at the tip shown in the photo to the left.

Severe damage can also occur by inappropriate use of the pritchel. Both of these effects require heating and reforging the tool.

There are two (2) distinct angles on a pritchel. One side is more acute than the other, in order to accommodate the shape of the horse nail shank. Working at the far edge of the anvil, angle both the pritchel and your hammer to forge each of the different angles.

Always work at the proper heat. Hammering the pritchel when it is cold will result in stress damage to the tool.

After the desired shape is forged into the pritchel, hit the tip of the pritchel with straight on hammer blows.
This will serve the double purpose of “packing” and squaring the pritchel tip.

With proper forging there should be very little need for grinding the pritchel. Heat treating will depend on the type of steel used in the pritchel. Refer to the tool steel guide for specific information.


Dealing with Scale

Oxidation occurs during the heating process, as air contacts the steel. This process creates what blacksmiths call scale or slag. In a properly built coal fire, positioning of the steel and control of the air blast helps to reduce the build up of scale on the work piece. Scale that is left on the steel during forging forces the scale into the steel, leaving a mark on the piece. The greater the scale build up, the less attractive the finished piece.

The Forgemaster TM forge eliminates the need for the blacksmith to constantly tend the fire as with coal. This allows for greater production time in a much cleaner environment. In the heating chamber of the Forgemaster TM forge, the air blast is in direct contact with the steel. The atmosphere that enables greater production and ease of work can also increase the amount of scale. A few simple steps will keep your work looking clean and crisp.

1) Only heat what you can easily work. Don’t overload the forge with work pieces. The heating ability of the Forgemaster TM is exceptional, and most experienced blacksmiths find that they can only keep up with a couple of pieces at a time. A piece of steel left in a gas forge heating chamber too long will develop a larger amount of scale.

2) Use the lowest temperature possible to reach forging heat and keep you busy is the ideal. Set your Forgemaster TM pressure regulator at as low a pressure as possible to keep up with the work you are doing. When working on small stock use low pressure (5 or so psi ). Larger stock may require up to 10-12 psi.

3) Work an edge first. Hammering on the flat face will result in hammering scale into the work. Light hammering on an edge will cause the scale to break lose and fall off of the work.

4) Brush the scale off. If hammering an edge is not possible, bending the steel will also loosen the scale. If neither of these techniques is practical for the piece, use a large bristle wire brush (Butcher Block brush) to remove scale prior to forging.


Relining a Forge

If you expect to get the best performance out of your Forgemaster TM you will need to pay attention to the liner. Lining walls that are worn to half of their original thickness will allow a greater heat loss, and will take longer to reach forging temperature. You know it’s time to reline the forge when:

• The lining material is worn greater than half the original thinkness of 2″.
• Moisture has been allowed to reach the ceramic lining material.
• The hearth brick is badly deterioated due to wear and vibration.
• The heart brick separates from the clip and loosens from the housing.

“Why should you reline your forge?”

• A new liner promotes longer forge life.
• A new liner prevents warping and damage to the steel housing.
• A new liner promotes better fuel consumption efficiency.
• A new liner promotes higher constant heat temperatures.

The May/June 1999 issue of the American Farriers Journal has a “tear out” page that will assist you in relining your forge. This special section was sponsored by Forgemaster TM as a courtesy to our customers. You will also want to check out our full page add in the AFJ Supplies and Services issue.


Apply Drill Tek

Step #1

Break the stick of drill tek into small (3/4″) pieces. The easiest method is shown below.

Step #2

After setting out all of the pieces of drill tek, and equipment, heat both heels of the horseshoe to a bright orange heat.

Step #3

Remove the shoe from the forge when it reaches a bright orange heat, and quickly brush the scale (don’t spend too much time with this or you will lose your heat). As soon as you have quickly brushed the scale, sprinkle some brazing flux onto the heels where you want to apply the drill tek. Then (using the pliers) place one piece of drill tek on each heel and return the shoe to the forge. It will not take long for the matrix of the drill tek to liquify. It is wise to remain close by and ready to remove the shoe AS SOON as the drill tek becomes shinney be ready, the brass will soon begins to flow.

Step #4

The moment the drill tek begins to flow, remove the shoe from the forge. Move to the anvil and drag the foot surface side of the shoe across a sharp edge of the anvil to remove any brass that flowed to the back side of the shoe. Then position the drill tek by using your hammer to gently move the particles while the brass is still in a liquid state. DO NOT QUENCH the horseshoe, allow it to air cool.

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Bundle Welding

One of the most versatile welds for the blacksmith is a bundle weld. By welding a collection of similar size pieces together you can create a variety of ornamental items. In this technique we will show the basic process of the bundle weld. Your imaginative application of this technique can add excitement to many of projects.

Bundle the desired number of pieces together. To hold the bundle together while heating and forging, wrap the pieces with wire or……………

An effective means of holding the pieces together during the forging process is to use an adjustable hose clamp.

After you have the bundle secured, place the end into the heating chamber of the Forgemaster TM. The heat chamber should be at welding temperature.

When the bundle has reached welding temperature, remove it and quickly brush off the scale and…….

apply welding flux. Both brushing and application of flux should be done quickly in order to retain heat. Return the bundle to the fire as soon a possible.

When the bundle again reaches welding temperature take the bundle to the anvil and with light rapid hammer blows forge the pieces together.

The completed bundle weld has been twisted and is ready for your application.

This bundle weld has been applied twisted with the ends spread in a “sun burst” pattern for a garden trellis. (click on the image for larger view)

The completed trellis.
(click on the image to for larger view)

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Forging a Natural Looking Leaf

Ornamental ironwork requires some practice to develop the necessary skills. This project will help develop several forging skills, and provide attractive leaves.
Select a 18″ length of 3/8″ round steel. You can use a shorter piece, but you will need to hold the piece in a pair of bolt tongs.

1) The first step is to forge the end to a point. At the edge of the anvil, angle the work piece and the hammer blows to effect a tapered end on the steel.

2) Now “neck down” a portion about 3/4″ behind the end of the steel. This is accomplished by using the edge of the anvil and the edge of the hammer to “fuller” the steel.

3) Next flatten and draw to the shape you wish. By using a cross pein hammer, you will move the steel faster and in the direction you want.

4) Fold the leaf in half, to forge the center vein in the leaf. Use the step of the anvil, and a cross pein hammer to begin the fold. Finish the fold on the face of the anvil. Hammer the crease area tightly to form the center vein of the leaf.

5) Heat the folded leaf, and begin to open the fold with a flat screw driver. Once the initial opening is made forge the leaf open using the edge of the anvil. Continue to forge the curls and shape that you desire.

6) Add the cross veining with a cross pein hammer…

7) Finish the leaf with a strong wire brush. For a bronze finish use a copper or brass brush.

Leaves forged in this manner may be welded together to enhance any ornamental project (see Forge Welding Tip).


Drain the Lines

When you are ready to shut the forge down, the following steps will help to increase the life of your fuel lines and regulator.

1) While the forge is running, close the tank valve.
2) Allow all of the propane to burn out of the fuel line.
3) After all of the propane has been consumed by the forge burners, turn the regulator pressure screw counter clockwise (to reduce pressure).
4) Finally close the forge fuel valve.

Following these steps will clear all propane vapor from the fuel lines and regulator. If you allow propane to remain in the fuel lines and regulator it will reduce the useful life of the fuel lines, because the propane vapor solidifies into a waxy substance that will clog the hoses, regulator and valves of your forge. This simple proceed ure will also prepare the equipment for your next job. When you next light the forge, you will open the tank valve first, then slowly increase the pressure at the regulator to the desired psi, and finally open the forge fuel valve for ignition.