Steel Selection by Kevin R. Cashen, www.cashenblades.com

[Dept of PMM Hall of Steel]

With the plethora of steels available today one can easily get lost in just selecting the one to use.  Each steel has its own chemical composition suited for the task for which it was made.  Alloying elements affect the qualities and characteristics of steel in many ways and it is worth knowing what some of those are.

 

Alloy Element	Positive Effects Upon Steel	Negative Effects Upon Steel
Carbon	Hardness, Strength, Abrasion Resistance	Embrittlement, Excess Carbides
Chromium	Corrosion Resistance, Hardenability	Red short, Retains Carbides
Manganese	Desulfurization, Strength, Hardenability, Wear Resistance	Lower Plasticity
Nickel	Toughness, Strength
Silicon	Deoxidizing agent, Hardenability, Toughness
Tungsten	High Temperature Strength, Abrasion Resistance, Grain Refiner	Red Hardness, Retains Carbides
Molybdenum	High Temperature Strength, Hardenability	Red Hardness
Vanadium	Grain Refinement, Toughness, Abrasion Resistance.	Some Red Hardness,Retains Carbides
Sulfur	Machinability	Embrittlement
Phosphorus	Machinability	Dendritic-banding structures resulting in weakness

 

To add to the confusion there are a few different classification systems of steel that identify the alloy chemistry or its characteristics.  The most common are the Number designations of the American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE).  In this numerical system the first two numbers refer to the alloy content and the second two (or three) numbers refer to the carbon content.

 

AISI/SAE Steel Classifications

10XX	Nonsulfurized Carbon Steels
11XX	Resulfurized Carbon Steels (Free Machining)
12XX	Rephosphorized & Resulfurized Carbon Steel
13XX	Manganese 1.75 (Principle Alloy)
23XX	Nickel 3.5
25XX	Nickel 5.00
31XX	Nickel 1.25; Chromium 0.65
33XX	Nickel 3.50; Chromium 1.55
40XX	Molybdenum 0.20 or 0.25
41XX	Chromium 0.50 or 0.95; Molybdenum0.12 or 0.20
43XX	Nickel 1.80; Chromium 0.50 or 0.80; Molybdenum 0.25
44XX	Molybdenum 0.40
45XX	Molybdenum 0.52
46XX	Nickel 1.80; Molybdenum 0.25
47XX	Nickel 1.05; Chromium 0.45; Molybdenum 0.20 or 0.35
48XX	Nickel 3.50; Molybdenum 0.25
50XX	Chromium 0.25; 0.40 or 0.50
50XXX	Carbon 1.00; Chromium 0.50
51XX	Chromium 0.80, 0.90, 0.95, 1.00
51XXX	Carbon 1.00; Chromium 1.05
52XXX	Carbon 1.00; Chromium1.45
61XX	Chromium 0.60, 0.80, 0.95; Vanadium 0.12
81XX	Nickel 0.30; Chromium 0.40; Molybdenum 0.12
86XX	Nickel 0.55; Chromium 0.50; Molybdenum 0.20
87XX	Nickel 0.55; Chromium 0.50; Molybdenum 0.25
88XX	Nickel 0.55; Chromium 0.50; Molybdenum 0.35
92XX	Manganese 0.85; Silicon 2.00; Chromium 0.35
93XX	Nickel 3.25; Chromium 1.20; Molybdenum 0.12
94XX	Nickel 0.45; Chromium 0.40; Molybdenum 0.12
98XX	Nickel 1.00; Chromium 0.80; Molybdenum 0.25

Another Classification of steels is that of Tool steels and is divided into groups according to their application, method of quench or special characteristics.

Tool Steel Classifications

Category	Example	Description
A	A2	Air Hardening
D	D2	Die Making Steel
F	F1	Special Purpose (Carbon-Tungsten)
H	H10	Hot Working
L	L6	Low Alloy
M	M10	High Speed (Molybdenum)
O	O1	Oil Hardening
P	P5	Mold Making
S	S7	Shock Resistant
T	T2	High Speed (Tungsten)
W	W2	Water Hardening

Before you make any kind of tool, or anything for that matter, you must first know what it is that you wish to make or accomplish.  Think about it, when man came up with catapults he didn’t build a big gangly contraption and then ask “OK now what can we do with this thing?  Hey lets try throwing stuff with it!”.  Man had a need to hurl massive missiles at long distances so he sat down and started planning a way to do it.

 

  Quite often I see blades done in the backwards manner previously described.  Would be makers find a piece of steel and then build a blade around it.  First, determine what your knife should have to do.  If it will be a scalpel, it can be very hard or perhaps stainless.  A specialized skinning knife will have edge holding and abrasion resistance as a top priority.  A large camp knife or sword will require good shock resistance to take the pounding of hacking and chopping.  So plan the knife and then determine the steel and the techniques to best achieve your goal.

Other considerations for steel besides the desired performance are your abilitites to work with a given alloy. Are you forging or stock removing? If you are forging some of these steels may present a serious challenge that may have you asking if it is worth the trouble. The simpler the steel the simpler can be the tools used to work it to satisfactory results. With all the things that can go wrong in forging the simpler alloys seem to be the best bet. Air hardening, hot hard and steels that may crack if worked improperly may be beyond a beginners abilities or even beyond the usefulness of such techniques at all. There are always those that say that they have forged good blades from very complex alloys, but are we pounding square pegs into round holes? The same quality knife (or better) could have been made much more easily with a steel better suited for the purpose. If you hear about all kinds of wild techniques and heat treating practices being done on a steel to make it really perform well, don't say "wow,that must be some steel" but instead ask if another steel could have done the job better without all the trouble. Even if you are just stock removing, the steel will have to be heat treated, are you and your equipment up to the challenge of some of the richer alloys?

 

  How do you determine which steel is best for a given application?  Fortunately this work has already been done for you.  Industry has spent many years and countless dollars researching, developing and making steels specifically for certain applications.  Why reinvent the wheel?  Just use all the information that they have already set up for you. Once again many makers seem to wish to ignore this helpful information and force square pegs into round holes.  Not that it can’t be done with a big enough hammer, but the round pegs fit much easier with less wear on you and your pegs.

In the table below you will find commonly available steels, their chemical composition and typical applications in which the are used. The ones that are highlighted may be clicked upon to take you to further information, including the Crucible Service Center or Admiral Steel page with all the the pertinent heat treating specifications and data. From there just one or two clicks should get you to ordering the steel of your dreams. Or if you wish to bypass my silly games and recommendations you can go directly to the home page of some the the bigger steel suppliers:
Admiral Steel
Carpenter Specialty Steels
Crucible Service Centers

 

Type	C	CR	Mn	Mo	Si	W	V	Other	Typical Applications
A2	1.0	5.25	.85	1.10	.35	-	.25	-	Blanking Dies, Thread Roll Dies, Forming Tools, Shear Blades, Gauges, Wear Inserts, forming rolls, hog knives, thread rollers, bending dies, cold blanking dies, coining dies, cold trimming dies, punches etc.
A6	.70	1.0	2.0	1.35	.30	-	-	-	Dies,Compression Molds, Lens Molds,Injection Molds, Transfer Molds
D2	1.55	11.5	.35	.80	.45	-	.80	-	Blanking Dies, Thread Roll Dies, Drawing Dies,Coining Dies,Trim Dies, Mold Inserts, Forming Rolls, Gauges, Injection Screw Components, burnishing tools, gauges, lathe centers.
L6	.75	.80	.70	.30	.25	-	-	1.5 Ni	Circular saws, Wood cutting band saws, Chipper & planer blades, Form Rolls, Straightening Rolls, Brake Dies, Shear Blades, Machine Tool Parts, Collets, Chucks, Pinions
M2	.85	4.15	.30	5.0	.30	6.4	2.0	-	Tools for heavy machining- Broaches, Milling Cutters, Counterbores, End Mills, Taps, Form Tools, Tool Bits,
O1	.90	.50	1.25	-	.30	.5	-	-	Abrasion resistant cutting tools- Blanking Dies,Jewelers Hobs, Engraving Tools, Paper Knives, Forming Tools, Taps (Hand), Gauges, Trim Dies, Broaches, drill bushings, knurling tools, reamers, taps, cold forming and bending dies, master tools, drawing dies, punches,coining dies, plastic molds, rubber molds etc..
O6	1.50	-	.75	.25	1.0	-	-	-	Parts requiring easy machining- Gauges, Bushings, Blanking Dies, Perforating Dies, Draw Dies.
S5	.60	.25	.85	.30	1.90	-	.20	-	Tools subjected to repeated heavy impact- Heading Tools, Chisels, Shear Blades, Rivet Sets, Concrete Breakers, Stamps, Hammers, Hand Tools.
S7	.55	3.25	.70	1.40	.35	-	.25	-	Punches and Dies Subject to Heavy Impact, Wire EDMed Punches & Dies, Warm Forging/Heading Dies, Plastic Injection Molds.
1060	.55-.65	-	.60-.90	-	-	-	-	-	Hand tools, shims,rule dies,scrapers.
1080	.65-.75	-	.60-.90	-	-	-	-	-	Hand tools, shims, rule dies,scrapers.
1084	.80-.93	-	.60-.90	-	-	-	-	-	Blades, hand tools,shims, & springs,rule dies,scrapers
1095	.9-1.03	-	.30-.50	-	-	-	-	-	Blades, hand tools, knives, shims, & springs, Flat & coil springs, rule dies,scrapers, & trowels
5160	.55-.64	.70-.90	.75-1.00	-	.15-.30	-	-	-	Leaf springs, Coil springs, scrapers, equalizers, bumpers,
52100	1.0	1.5	.35	-	.25	-	-	-	Ball Bearings, Roller Bearings, Bearing Races, Gauges, Drawing Dies, Mandrels, Drills (Non-Ferrous).
W2	.60-1.40	.15 max	.10-.40	-	.10-.40	-	.25	-	Blanking tools, Chisels, Shear blades, Drills, Glass Cutters,Lathe tools, Reamers, Hand Taps and Dies,Twist Drills,Woodworking Tools,Wear Plates, Razor Blades.

 

The list above is not to be read in reverse, it is meant to tell you what the steels are best suited for, not what old rusty junk could be made of.  The first commandment of bladesmithing is KNOW THY STEEL.  Scrap or mystery steel is great for forging or grinding practice, but if you are going to heat-treat it you have to know your parameters (you have to know what it is).  If you are going to take it all the way to a finished product isn’t it worth knowing it will be the best you can get when you are done with all that work?  You owe it to yourself and your customers to do it right.  You hear it again and again, “Old saw blades should be L6”, “leaf springs should be 5160” “files should be W2”, if there is any "shoulds" or guesses involved you have already compromised your results.  Saws, springs, files etc. have all changed over the years and can have anything in them at any given manufacturers whim. Many people have been unpleasantly surprised to find that the seemingly hard objects that they made their blades out of were just surfaced hardened soft steel, a practice becoming more popular for its cost savings in industry. So don’t be surprised that if the blade you made out of old junk is, well…junk!  The absolute worst reason for this practice is cost savings, as this is a very false economy.  The time and materials wasted on an unacceptable blade made from mystery steel is far more expensive than the priciest steels out there.  Most steel in blade size sections are surprising inexpensive and can be delivered right to your doorstep, with chemical analysis and heat treating specifications, with just one phone call.