Steels Useful for Tools
by Dave Smucker
I call this article Steels useful for Tools, rather than just calling it "Tool Steel" because there are a number of very useful steels for the blacksmith that fall outside of the Tool Steel classification.
Purchase of Steels vs. used, scrapped, recycled, or found steels. Well, it all comes down to time and money. What is your time worth? Do you have the money? I have heard many professional / full time blacksmiths strongly tell folks that they should only be using new, high quality special tool steels when making tools. For them this is 100 percent correct – look at it this way, their time is worth at least a dollar a minute. So, spending 15 minutes heating, straightening and prepping, a piece of old auto spring to make a tool is a real waste of money and their limited time. They may even finish the tool and find it cracks. If this happens, they have really wasted their money. However, the part time hobby blacksmith may just not have the money to spend on new tool steel. Time might be limited, but money is even more limited and the idea of making something useful out of nearly free material is just too good to pass up. Blacksmiths will want to do what best fits them and their personal needs.
"Spring Steel is NOT TOOL STEEL" This is one of Francis Whitaker's famous comments. Well, my reply "YES IT IS". Spring steel works damn well for many tools. Blacksmiths 100 years ago would have loved to have it for many tools so let's not be so fast to turn our nose up at some very good steel. Not all springs are the same spring steel, for example 5160, because the end user of the spring is always trying to find a balance between cost and life. Used in normal service, most springs will fail at some point. Not knowing for sure what steel is what, leads us to using the "Break Test" discussed elsewhere in this issue of the AACB Newsletter.
There are other "engineering steels" that are also very useful for any number of tools and we will look at some of the important ones. This is especially true if you can find spring steel or engineering steels as new material in the form of drops, off cuts etc. We will talk more about scrap steels vs. junk steels in this article.
My Tool Steel is Better Than Your Tool Steel Oh, the wonderful world of marketing. Before we get into the classification of different steels, I would like to say a little about the marketing of Engineering and Tool Steels. Yes, there can be a difference between Company ABC's S7 tool steel and Company XYZ's S7 tools steel but for our crude uses in blacksmithing. I don't think any of us can tell the difference. In my aluminum work we purchased most of our steels to generic specifications. It was only for some very special applications such as high service, high expense items such as "forged hot mill rolls" that we could measure one supplier's performance as better than another's.
I will even give a little insider information here. For a number of our customers we might help them with their end product by taking one of the standard aluminum alloys and make small adjustments in the composition and process so that it worked well in the customer's forming and finishing operations. We would give these special alloys a "C Number" rather than the standard Aluminum Association Alloy Number. It was special and required special handling, casting, rolling and processing. The customer paid more and got what they paid for. For some other customers, marketing would assign a special alloy "C Number" but the product would be just the same as the standard alloy product except it would be a bit higher priced. The customer was happy because he thought he was getting something special – but in fact, all he was paying for was the name – not the product. Buyers beware.
My example in the blacksmithing world is "Atlantic-33", also known as Flutagon. Hey, this is good stuff and a very good tool steel. I believe it to be either S1 or S6 or very close to one of these standard tool steels. Today I think S7 is a better material. (If I can get a small sample of Flutagon for testing, I will report on what it really is – besides good marketing.)
Steel classification and naming
Many of us have become comfortable with much of the naming systems used in the USA for steels but for others it is a very confusing world. Our systems can be confusing, but if you add in the other international systems, it gets real confusing. I am always learning something new in this area.
We have a number of common systems in use in the USA plus various steel manufacturers give their steels their own proprietary names or grades. On top of all of this we have purchasing specifications developed by the American Society for Testing and Materials (ASTM) that cover a number of important steels for industrial use.
The basic system of steel classification developed by American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE) uses a 4 number system to identify various plain carbon and alloy steels. This classification system considers steels with less than 4 percent alloy content to be alloy and / or plain carbon steels and steels with 4 percent or greater alloy content to be special types of alloy steel, namely stainless steels and tool steels.
Table # 1
|Type of Steel ||Number ||Comments |
| Plain Carbon Steel || 10XX ||1020 is a mild steel, 1045 medium carbon, 1095 high carbon. 1095 is the similar to W1 tool steel, a very good steel for woodworking tools. 1060 steels have been used for many hammers.|
|Re sulphurized Steel ||11XX ||Steel to which sulfur has been added in controlled amounts after refining. The sulfur is added to improve machinability. It may give you problems in forging |
|Manganese Alloy Steel ||13XX
15XX ||1541 is a high manganese alloy steel now being used in auto axles. (In other words, not all axles are 4140 anymore.) |
| Nickel Alloy Steel |
| 3 – 1/2 % Ni ||23XX ||2317 Some times used for case hardened gears under 8 inch dia. |
| 5 % Ni ||25XX|
| Nickel-Chromium Alloy Steel|
| 1 – 1/4 % Ni 0.6 % Cr ||31XX|
| Molybdenum Alloy Steel |
|Molybdenum ||40XX ||Used in some case hardening application and for some screw products |
| Chromium-Molybdenum ||41XX ||4140 and 4150 widely used engineering steels. 4119 is a special Timken steel used for roller bearings that have a very deep case hardening. |
| Nickel-Chromium-Molybdenum ||43XX ||4340 another important engineering steel. This steel along with 4140 is very useful for tools |
|1 - 3/4% Ni - Molybdenum ||46XX |
|3 – 1/2% Ni - Molybdenum ||48XX ||Used for case hardening applications especially for gears. |
|Chromium Alloy Steel |
|1/2% Cr ||50XX |
|1 % Cr ||51XX ||5160 has 1% Cr 0.6% Carbon (60 points) it is a widely used spring steel. Very useful for blacksmithing tools and woodworking tools.|
|1 – 1/2% Cr || 52XXX ||52100 has 1 – 1/2% Cr and 1% Carbon (100) points. This is the most common ball bearing steel. We use a similar steel for making rolls for cold rolling mills. |
|Chromium-Vanadium Alloy Steel ||61XX ||6150 also a useful steel for some tools. It is used in piston rods pins and spline shafts|
|Chromium-Nickel-Molybdenum Alloy Steel ||86XX
||8620 a widely used case hardening steel used for gears and other parts |
| Silicon-Manganese Alloy Steel ||92XX ||9255 another steel used for springs subjected to high shock loads.
Notes: 1.) The last 2 (or 3) digits "XX" are the "points of carbon" in the steel 2.) Case hardening is the process where carbon is added to the surface of a part during the heat-treating process. This "case" allows the surface layers to be heat treated to a very high hardness and yet retain a very tough but softer "core" to the part being made.
What about Steels like A36 orA514 they are not in your list?
A steel like A36 is not listed in the AISI/SAE system because it is a purchasing specification from the ASTM. The American Society for Testing and Materials issues a large series of purchasing specifications covering many materials. Ferrous materials happen to start with the letter A (B is for nonferrous, C for ceramic, concrete and masonry materials etc.) The number in the identification is just a number assigned in sequence; the number 36 in A36 does not mean anything special. (There is a lot of confusion on this since one requirement of A36 is for it to have minimum yield strength of 36,000 psi.) Some ASTM specifications match up with steels in the AISI/SAE classification system but many do not. For the record, A36 is a hot rolled structural steel suitable for welding. It can have up to 0.29 percent carbon and manganese that ranges from 0.60 to 1.20 percent. Blacksmiths used a great deal of this steel for making things and seem to love to hate it.
Real Tool Steels (Francis would like that.)
Tool Steels have greater than 4 % alloy content. One of the difficulties we used to have in getting good information about tool steels is that they are made by a small group of specialty steel producers using special metallurgical processes and have generally be made available with proprietary names or grades. In more recent years, better clarification has come through the development of a classification system now widely accepted throughout the industry. You will still find the proprietary names when working with various suppliers and for critical industrial applications, there can be a real difference between suppliers for a given grade. I don’t think that this is something that is of any concern to most blacksmithing applications. In addition, two important tool steel types, namely W and O, really don’t fit the greater than 4 % alloy definition but are basic to tools blacksmiths find useful.
Unlike the “standard steels” (low carbon and alloy steels) the common classification system for “tool steels” uses a letter and number identifier. The source of the letter can be tied to alloy, quenching media, or common end use. This can be very confusing at times. Table # 2, Tool Steel, on the following page lists the common types.
How do alloying elements affect these characteristics?
Carbon (C)is the basic element that gives tool steels their hardness and lets us do the heat-treating. It is essential in low alloy tool steels -- needs to be 0.60 percent (or 60 points) and higher. At the high end of the percentage range, up to 1.00 percent plus (100 + points of carbon) it adds considerably to the wear resistance. It is the element that makes the very important blacksmith tool steel W1 what it is.
Manganese (Mn) improves forgeability and reduces brittleness. In low alloy tool steels, it may allow the use of oil for quenching in some applications.
Silicon (Si) is not a major element in most tool steel but is important in their manufacture as a deoxidizer. In conjunction with Manganese, it is important in S5, which is an extremely tough Silicon-Manganese tool steel with outstanding shock and abrasion resistance. S5 was the tool steel most favored by my pre-retirement employer (Alcoa) for use in air hammer tooling used by the brick masons. Alcoa uses a great number of these tools in rebuilding melting furnaces.
A Short History of Tool Steels
Back in the days before the development of the Bessemer Converter (1854), we basically had two ferrous materials. Wrought iron and steel. Wrought iron was the common everyday stuff that was used to make most things and "steel" was Tool Steel used to make all forms of cutting edges and cutting tools. The wrought iron was a very low carbon material but did contain several percent of a silicon oxide slag from the refining process. Steel, or as I will called it, Tool Steel, was wrought iron with a fair amount of carbon added. There were no "mild steels"; they came only with the Bessemer process. Steels generally had between 0.50 and 1 percent carbon. A steel with 1 percent carbon would be similar to our W1.
For centuries these steel were made by taking the best grades of wrought iron and packing them in charcoal in a clay box and then heating for 6 to 8 days at 2000F. The iron would absorb carbon from the charcoal and become "Blister Steel". For better grades, this was folded and forged welded into "shear quality" steel.
Still, the quality varied a great deal and in the 1740's a clock maker by the name of Huntsman, frustrated that he couldn't get good steel for springs, came up with the crucible process for making cast tool steel. He took blister steel and melted it in a sealed clay crucible. First, this was just iron and carbon but later alloy metals were added. This process was used until the mid 1950's. In the early 1900's the electric arc furnace came into use for making tool and specialty steels and almost 100 percent are made that way today.
What is important in a tool steel?Why do we have so many different types? Well, mostly because no one steel can do all things for all people and do it at a low cost. It is kind of like you can “have a hard steel, a tough steel, a low distortion steel, a lower cost steel -- pick any two of the four. In other words, a steel can be designed for a given application -- but usually is a mixture of various trade offs. If you want to select a steel for a given application or tool, you need to look at the following characteristics:
1.) Heat resistance or hot hardness. How does it perform at higher temperatures? Can we use it on hot metal?
2.) Shock resistance. How tough is the steel? How strong? What is the depth of hardness?
3.) Wear resistance. How well does it handle abrasion, how well does it hold an edge? How hard is it?
4.) Machinability. How easy is it to saw, drill and machine in its soft or annealed state?
5.) Forgeability. How easy is it to forge? How small is the forging temperature range? Does it go “hot short”?
6.) Ease of heat-treating. What is used to quench from critical temperature, water, oil, air, etc.? How prone to cracking is the steel on quenching? How much does it distort?
7.) Availability. While cost is a factor, in most cases “availability” to the blacksmith in small quantities and reasonable sizes is the big issue. In addition, can we find the material as scrap
Tungsten (W) is a very important element in many tool steels giving both hot hardness and wear resistance. T1 (18.0 percent Tungsten) was the first of the high-speed tool steels used for cutting tools in machine shops. It has been around since about 1900. The chemical symbol W is from the German name for the element “Wolfram”. (My German friends don’t call it TIG welding but rather WIG welding.)
Vanadium (V) acts as a grain refiner and thus improves the forgeability of the tool steel. It also forms a very hard Vanadium carbine that improves both hardness and wear. In large amounts (above 1.0 percent), it makes the tool steel much harder to grind.
Molybdenum (Mo) At low percentages Moly improves both deep hardening and toughness. In high percentages, it is used in some tool steels to replace Tungsten.
Cobalt (Co) increases the hot hardness of tool steels used in some cutting tool applications. It also increases the critical temperature making heat-treating more difficult and leading to decarburization.
Chromium (Cr) is a major alloying element in many tool steels improving hardenability (depth of hardness) and can improve both wear resistance and toughness. We find it in many steels including the alloy steels, 4140 (chrome moly engineering steel), 5160 (spring steel) and 52100 (bearing steel) all of which are useful to blacksmiths because we can find them at low cost as scrap.
Nickel (Ni) Used with other elements, such as chrome, to improve the toughness of some tool and alloy steels. An important element in L6.
Tool Steels (table # 2)
|Letter Symbol ||Category Designation ||Group Designation ||Some Typical End Uses
|M ||High-Speed Tool Steels (the M is for Molybdenum) ||Molybdenum types ||Drill bits, end mills, taps, threading dies
|T ||High-Speed Tool Steels (the T is for Tool or maybe Tungsten ?) ||Tungsten types (the chemical symbol for Tungsten is W) ||Milling cutters, lathe bits
| H1 - H19 ||Hot-Work Tool Steels (the H is for Hot) ||Chromium types ||Hot cuts, extrusion dies, hot mill rolls
|H20 - H39
||Hot-Work Tool Steels (the H is for Hot) ||Tungsten types ||Extrusion dies, hot forging dies
|H40 - H59 ||Hot-Work Tool Steels (the H is for Hot) || Molybdenum types ||Special high temperature hot work
| D ||Cold-Work Tool Steel (the D is for Die) || High carbon, high chromium types ||Metal forming dies (cold work) coining dies, tread rolling dies
|A ||Cold-Work Tool Steel (the A is for Air) ||Medium alloy, air quenching types ||Die casting, shear knifes, trimming dies
|O ||Cold-Work Tool Steel (the O is for Oil) || Oil quenching types ||Drawing dies, coining dies, die casting dies
|W ||Water-quenching Tool Steel, also a Cold-Work Tool Steel ||Low alloy, high carbon (the W is for water quenching) ||Hand tools, blacksmith tools, wood working tools
|S ||Shock-Resisting Tool Steel (the S is for Shock) ||Lower carbon, alloyed for toughness ||Pneumatic Chisels, Blacksmithing and boilermaker’s tools
| P ||Mold Steels (P is for plastic) ||carburizing steel (case hardening) ||Plastics molds
|L ||Special-Purpose Tool Steels (L is for Low alloy) ||Low-Alloy types (L6, does have 1.5 percent nickel) ||Large sawmill band saw blades
|F ||Special-Purpose Tool Steels (F is for, ”I don’t have a clue”) ||Special-Purpose Tool Steels (F is for, ”I don’t have a clue”) || Some abrasion-resistant applications
What tool and alloy steels are useful to the Blacksmith?
With all of the above as just so much information you may be saying, OK, what tool steels are useful to me as a blacksmith, how do I forge and heat-treat them and where can I find the stuff? What follows is my opinion on some of the tool and alloy steels based on my industrial and blacksmithing experience.
I sure would like to hear from some of you on your experience and what has worked and not worked for you for various blacksmithing applications. I would like to report that information in future articles.
Here is what I think of some of these steels -- in the article Heat-Treating Tool Steels in this issue I talk about heat-treating and working with these steels.
Alloy Steels -- useful for tooling (table # 3)
|Name ||Category or type ||Make up of steel ||Some typical uses|
|4140 or 4340 ||Engineering steel, widely use for equipment applications ||Chrome Moly steel or Chrome Moly Nickel steel -- 0.40 C ||Hammers, tongs, anvil tools, power hammer tooling, power hammer dies |
|4119 ||Timken bearing steel ||Deep case hardened used in roller bearing from Timken ||Both rollers and races can be reforged into tools |
|5160 ||Coil and flat spring steel ||Medium high carbon chrome steel with 0.60 C ||Drifts, punches, and power hammer tooling.|
|52100 ||Ball Bearing Steel ||Most non Timken bearings ||Tooling |
|8620 ||Case hardening steel -- gearing ||Nickel Chrome Moly steel used in case hardening applications ||Tongs |
| Railroad rail ||Specification is in weight per yard, such as 115 pound rail ||Steel varies by manufacturer but is similar to 1080 with about 1 percent manganese ||Power hammer tooling, hammers,
W1 also sometimes found as 1095 and as “Water hardening drill rod.” This is the basic old-line blacksmithing tool steel. For many applications, it remains one of the best steels for the blacksmith. It is defined as a cold work tool steel, since it loses its hardness at hot metal temperature -- and therefore is not a hot working tool steel. It still is a good steel for making punches and cold cuts. I like it for things like “eye” punches. You just have to remember to cool it after each use to avoid drawing the temper.
Francis Whitaker used it for making a great deal of his tooling and I believe liked it for things like hammers. (I prefer 4140 or 1080 for hammers.) It makes some of the finest woodworking tools and many of the knife makers use it a great deal. Most old files are made from W1. It requires quenching with water to obtain good hardness. Because of this, the depth of hardness is limited (usually about a max. of 0.060 inch) and tools retain a rather tough core. I think that W1 and how to use it should be part of the blacksmith basic knowledge or “tool kit”.
Clay Spencer uses W1 for a lot of his treadle hammer tool. He like it for most tools with the exception of hot cuts.
H13, Hot work tool steel. Another of my favored tool steels, this time for making tools intended for long exposure to hot metal. This includes hot cuts, hot hardies and heavy-duty punches. It also makes good drifts for opening up holes etc., although I use 5160 spring steel for most of these.
The hot work tool steels were developed for heavy hot working industrial applications such as forging dies, extrusion dies and hot mill rolls. The reason to use H13 over any of the other “H” steels is that you can find it in small sections both round and plate.
It is available in small quantities and a number of smiths sell it as a “tail gate” item at various blacksmith meetings. Reportedly, it is also used in guide pin application in plastic molding and may be available to use as drops form some “die shops”. It is an air-quenching tool steel, and very difficult to anneal with simple equipment. So if you want to saw it or machine it, that needs to be done before any forging or heat treatment.
Joe Miller loves H13 and uses it for both hot tools and a number of the cold work dies he uses under his power hammers. He has had very good life in this application using it in many production runs.
S7, A Shock-Resisting Tool Steel can be found in some jackhammer tools or bits (they can also be S1 or S5). It is a very tough steel that take impact loading extremely well. It also has good hot work properties and is used in applications up to 1000 degrees F. I have used it for hot cuts, and for that application don’t see any major difference from H13. Many blacksmiths make hardies from S7, where they have obtained the steel from old jack hammer bits.
Some blacksmiths have used S7 to make special power hammer tools where they machined a pattern into the tool and then used that tool on hot metal under the power hammer. It is an air hardening (air quenching) tool steel and heat treating it is much like working with H13. Because it is air hardening and very tough, many machine shops like it for tooling applications and it has replaced O1 in many tooling applications. You can buy it in most common drill rod sizes.
Some manufacturers make their power hammer dies from S7. If I could have only one tool steel in addition to W1, it would be S7. I know many blacksmiths love H13 but I really think that for most applications, both hot and cold that S7 is even better.
O1, is not a tool steel that I like – I use either A2 or S7 or even W1 instead, but you will find it as one of the most common drill rod steels. (It was widely used by machine shops because of low distortion in heat treatment. Today A2 fills that bill better.)
A2, The most common air hardening (air quench) tool steel in the USA today. I haven’t used this steel for blacksmithing tools, but like it very well for tools and gauges etc. that are machined and then heat treated. Some folks have made woodworking tools from A2.
Steve Williamson has made a number of his hand held punches out of A2 and likes it for these tools.
4140 and 4340 are the most common general purpose engineering steels today. Used for many equipment applications, I like these steels for making hammers and tongs. Many smiths use mild steel for making tongs, but I like to use either 4140 or 4340 because of their much greater strength and toughness. This allows you to make the tongs with thinner jaws along with smaller and springier reins or handles. The one major limitation with these alloy tongs is that you can’t quench them from a red heat. You must let them cool well into the black range if you are going to cool them in your slack tub.
5160, Spring steel, found in some automotive coil and most flat springs. I like this steel for power hammer tooling and for heavy duty, "bash on it tooling" like drifts. I have even made a few hot cuts and punches from this material. From time to time I have had cracking problems with some of this material -- likely from cracks already in the old springs. Not all springs are 5160 so your results may depend on the type of steel in the spring. Read the article on "Break-Testing".
Railroad rail or 1080 steel with the addition of about 1 percent manganese. A very high quality, very clean steel that makes good hammers and power hammer dies. You can buy this material as scrap at reasonable prices. If you are going to try to saw railroad rail, cut from the bottom up -- as the rail head is usually work hardened. If you have a power hammer, you can work rail into very useful sections for many tool applications. It's not quite as high in carbon as W1 but still at 0.80 carbon will heat-treat very well as water quench steel. For small tools, you can use an oil quench.
Rebar is Junk,not quality scrap steel useful for tools. It is one material I think you are really wasting your your time trying to use for tools. I also don't think A36 is useful for much except handles and tongs. A36 can be used for female dies for use in the treadle or power hammer, but if you can make these out of better material, you will get much longer life.
If you want more information, background or detail on these and other steels, see the following references:
Machinery's Handbook, now in its 27th edition edited by Robert E. Green and Christopher J. McCauley. Industrial Press Inc. (I was using the 25th for this article. Every blacksmith, machinist or mechanical engineer should have a copy of this handbook. You can find older editions of this book at good prices in the used book market.)
Heat Treatment, Selection and Application of Tool Steels, by Bill Bryson, Hanser Gardner Publications
Engineering Properties of Steel, Philip D. Harvey Editor, American Society for Metals
Copyright 2001, 2005 by David E. Smucker Note to other editors of blacksmith newsletters. You are free to use this article in your publication provide you used it in its entirety and credit the Appalachian Area Chapter of Blacksmiths and author. I can provide you with an electronic copy by contacting me at email@example.com It may not be reproduced in any form for commercial use.
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