Looking for history of 5160 spring steel

Ian · 1st March 2020, 12:30 PM

Alloy steel 5160 (a.k.a. AISI 5160) is a high carbon, chromium containing alloy that is often used to make excellent large knives and swords. It's main commercial use has been in the manufacture of leaf suspension springs for automobiles and trucks. In some parts of the world, such as the Philippines, these leaf springs are scavenged from old vehicles and the steel is forged into edged tools and weapons.

I have been trying to determine the history of 5160 steel, when it was first produced, and when it was first used in the leaf springs of vehicles. Have automobile springs always been made from 5160 steel? Searching the web has not yielded much information and I am obviously not looking in the right places. Perhaps someone can point me in the right direction or has a pertinent reference.

Why I'm interested in the 5160 story is that the composition of the alloy and its associated properties make it very useful for large knives and swords, and if we know that this alloy has been used in a particular piece we may be able to date it more precisely. The amount of scrap 5160 available may also be a determining factor. For example, in the immediate post-WWII period huge numbers of U.S. vehicles were made redundant and abandoned or destroyed in the Philippines, at which time large amounts of scrap 5160 would have been available relative to pre-WWII.

I'm hoping you have some answers.

Regards,

Ian.

mariusgmioc · 1st March 2020, 03:26 PM

Interesting topic!

Not the answers you seek but more of what you were saying.

In Nepal the leaf springs are the main source of raw steel material for the Kukris...

http://gurkhakukris.com/Content/cms/index.php?id=43

Moreover, as far as I know most modern combat-ready swords (like those made by Hanwei Forge for example) are made of this steel.

Will M · 1st March 2020, 05:30 PM

Wilkinson sword used steel very similar to 1095. Main sword manufacturers thought this was the best steel to use for swords. If modern makers use some other steels they probably use it due to availability or ease of manufacture as they are now made by stock removal, not forged and shaped..

Ian · 1st March 2020, 05:41 PM

Will,

I think the main attractions of 5160 are that it is a readily available, durable steel that can be hardened to take a keen edge, and that it is a type of spring steel that can be bent and it will return to its original state (up to a certain limit of course). The small amount of chromium in the alloy seems important in that respect.

The edged weapons and tools in many developing countries are still largely forged by locals from materials on hand, which is why scrap leaf springs are sought out. 5160 does not need to be folded or have an inserted edge because it has desired properties of toughness, edge retention, and springiness without being combined with other metals. For this reason, I know from personal experience that scrap springs have been widely used in the Philippines, Mexico, and Thailand. Interesting to learn from marius that Nepalese kukhri are also made from the same material.

Ian

mariusgmioc · 1st March 2020, 06:57 PM

Well Ian... yes and no.

While some smiths may use it for its availability, it definitely does not explain why big, major, modern companies use it. Hanwei for example has easy access to other high alloyed steels.

Its exceptional mechanical properties that makes it an almost ideal steel for swords and other bigger blades. From all I know, it has only two minuses:
1. it is rather sensitive to rusting and,
2. it is somehow harder to be worked.

Edster · 1st March 2020, 07:07 PM

Ian,

Interesting subject. Not sure if this addresses your needs, but I found them informative.

Try this one."Leaf Springs: Their Characteristics & Methods of Specification, 1912. Free Google Book.
https://books.google.com/books?id=6T...spring&f=false

Author says that the modulus of elasticity of all steels are virtually the same. Springs made with carbon steel "ride" the same as those of alloy steel of same dimensions. Alloy improved the resistance to repeated deflections. Other alloy additions modified other desirable qualities in manufacturing & use.

While not specifically addressed in text 5160's alloy composition enhances other qualities of the carbon steel, not springiness.

Steel grade standards developed first for structural steels and then to needs of the train and auto industries for consistency to engineering needs and design qualities.

Sword makers in Sudan & elsewhere transitioned from bloomery irons to a good material, i.e. carbon alloy steels from railroads or lorry springs when they became available after c. 1900. I guess it just happened that what steel that made good vehicle springs also made good swords.

Regards,
Ed

Chris Evans · 2nd March 2020, 12:12 AM

Hi Folks,

An overview of 5160:https://www.azom.com/article.aspx?ArticleID=6743

A good article on how to best heat treat 5160: https://knifesteelnerds.com/2019/04/...at-treat-5160/

And where 5160 sits in terms of toughness among forging cutlery steels: https://knifesteelnerds.com/2020/02/...-knife-steels/

Ian: You could ask Larrin at Knife Steel nerds when 5160 came into generall usage: https://knifesteelnerds.com/

Cheers
Chris

Ian · 2nd March 2020, 08:22 AM

Marius, Ed and Chris.

Thanks for your thoughts and suggestions. Much appreciated. I will report back here if I discover anything useful.

Ian.

Ian · 3rd March 2020, 08:37 AM

Chris,

I sent off an email to Larrin Thomas, as you suggested. What a nice guy! He sent me a prompt reply which is copied below.

Quote:

Hi Ian,

Finding steel history can be surprisingly difficult, and 5160 is not one I have looked into. I was unable to find the history of 5160. However, I looked some at some of SAE journals from the early 20th century and found a couple things. I found a reference to 5165 steel in the 1913 journal: https://babel.hathitrust.org/cgi/pt?...ew=1up&seq=638

5165 was not present in the 1912 SAE transactions: https://babel.hathitrust.org/cgi/pt?...iew=1up&seq=51

The chromium limits of 5165 were changed in 1919: https://babel.hathitrust.org/cgi/pt?...iew=1up&seq=14

However, 5165 was removed from the SAE specifications in 1922 "as there is apparently no use for it, and 5150 has been added for shafting material and for gear purposes." https://babel.hathitrust.org/cgi/pt?...ew=1up&seq=218

I found an ad from United Steel in 1919 advertising for "spring steel" which had four different brands including "Crucia" a Chrome-Carbon steel. https://babel.hathitrust.org/cgi/pt?...iew=1up&seq=88

So I didn't find 5160 but early versions of the steel date back to at least 1913. Perhaps with this starting point you can find something.

Larrin

And a further follow-up reply ...

Quote:

Ian,

I found a reference to 5160 in a 1952 book, though it doesn't talk about 5160 as being the most common choice for springs, just one of the choices. https://babel.hathitrust.org/cgi/pt?...ew=1up&seq=483

Larrin

Chris Evans · 4th March 2020, 04:28 AM

Quote:

Originally Posted by Ian

. It's main commercial use has been in the manufacture of leaf suspension springs for automobiles and trucks. In some parts of the world, such as the Philippines, these leaf springs are scavenged from old vehicles and the steel is forged into edged tools and weapons.

Ian,

Leaf springs have been made from a variety of steels, not just 5160. Over the years I have seen mentioned 9260, L6 and the higher carbon content 10xx series including 1095.

So we must not make the assumption that just because many leaf springs were made from 5160, that all were of the same material.

As an aside, making swords and knives from discarded used leaf springs is not a very good idea because these springs develop micro fatigue cracks that are an invitation for later breakage in a sword of knife.

As another aside, the village blacksmiths in SE Asia tend to only harden the edges with a shallow edge quench and leave the rest of the blade soft, which mitigates the above risk, though it would not work all that well with thin bladed swords, at least not to our expectations.

Cheers
Chris

Ian · 4th March 2020, 05:59 AM

Quote:

Originally Posted by Chris Evans

Ian,

Leaf springs have been made from a variety of steels, not just 5160. Over the years I have seen mentioned 9260, L6 and the higher carbon content 10xx series including 1095.

So we must not make the assumption that just because many leaf springs were made from 5160, that all were of the same material. ...

Very true. I am reading now some of the other materials used for leaf springs and will report back shortly.

Quote:

... As an aside, making swords and knives from discarded used leaf springs is not a very good idea because these springs develop micro fatigue cracks that are an invitation for later breakage in a sword of knife. ...

Chris, would not some of these mirco-cracks be corrected during the forging process? The bar stock provided by a leaf would need to be worked extensively on the forge to get to a knife or sword blade.

Quote:

... As another aside, the village blacksmiths in SE Asia tend to only harden the edges with a shallow edge quench and leave the rest of the blade soft, which mitigates the above risk, though it would not work all that well with thin bladed swords, at least not to our expectations. ...

Chris, I agree, but I don't think there are a lot of thin-bladed weapons or tools made from these sources. What I have seen are nearly all fairly sturdy pieces that are designed to last a long time. I know people who have had the same bolo for 20+ years and used it regularly.

Chris Evans · 4th March 2020, 06:22 AM

Quote:

Originally Posted by Ian

Chris, would not some of these mirco-cracks be corrected during the forging process?

Maybe, but chances are against it. The inside surfaces of the crack become oxidized and are unlikely to weld shut, unless a flux is introduced.

The practice of recycling used leaf springs is not best practice because for starters one does not know the steel's composition and thus the heat treatment cannot be optimized. And then there's the matter of the said fatigue cracks.

In summary, it is one of those things that is widely done in the poorer regions of the world with the assumotion that near enough is good enough and things are OK until they are not.

This subject has been discussed over and over on blade smith forums and the experts always prefer new steel of a known composition. After all, plain and low alloy carbon steels are quite cheap.

Cheers
Chris

1st March 2020, 12:30 PM	#1
Ian Vikingsword Staff Join Date: Dec 2004 Location: The Aussie Bush Posts: 4,203	Looking for history of 5160 spring steel Alloy steel 5160 (a.k.a. AISI 5160) is a high carbon, chromium containing alloy that is often used to make excellent large knives and swords. It's main commercial use has been in the manufacture of leaf suspension springs for automobiles and trucks. In some parts of the world, such as the Philippines, these leaf springs are scavenged from old vehicles and the steel is forged into edged tools and weapons. I have been trying to determine the history of 5160 steel, when it was first produced, and when it was first used in the leaf springs of vehicles. Have automobile springs always been made from 5160 steel? Searching the web has not yielded much information and I am obviously not looking in the right places. Perhaps someone can point me in the right direction or has a pertinent reference. Why I'm interested in the 5160 story is that the composition of the alloy and its associated properties make it very useful for large knives and swords, and if we know that this alloy has been used in a particular piece we may be able to date it more precisely. The amount of scrap 5160 available may also be a determining factor. For example, in the immediate post-WWII period huge numbers of U.S. vehicles were made redundant and abandoned or destroyed in the Philippines, at which time large amounts of scrap 5160 would have been available relative to pre-WWII. I'm hoping you have some answers. Regards, Ian.

1st March 2020, 05:41 PM	#4
Ian Vikingsword Staff Join Date: Dec 2004 Location: The Aussie Bush Posts: 4,203	Will, I think the main attractions of 5160 are that it is a readily available, durable steel that can be hardened to take a keen edge, and that it is a type of spring steel that can be bent and it will return to its original state (up to a certain limit of course). The small amount of chromium in the alloy seems important in that respect. The edged weapons and tools in many developing countries are still largely forged by locals from materials on hand, which is why scrap leaf springs are sought out. 5160 does not need to be folded or have an inserted edge because it has desired properties of toughness, edge retention, and springiness without being combined with other metals. For this reason, I know from personal experience that scrap springs have been widely used in the Philippines, Mexico, and Thailand. Interesting to learn from marius that Nepalese kukhri are also made from the same material. Ian Last edited by Ian; 1st March 2020 at 05:58 PM.

1st March 2020, 03:26 PM	#2
mariusgmioc Member Join Date: Sep 2014 Location: Austria Posts: 1,903	Interesting topic! Not the answers you seek but more of what you were saying. In Nepal the leaf springs are the main source of raw steel material for the Kukris... http://gurkhakukris.com/Content/cms/index.php?id=43 Moreover, as far as I know most modern combat-ready swords (like those made by Hanwei Forge for example) are made of this steel.

1st March 2020, 05:30 PM	#3
Will M Member Join Date: Mar 2012 Location: In the wee woods north of Napanee Ontario Posts: 391	Wilkinson sword used steel very similar to 1095. Main sword manufacturers thought this was the best steel to use for swords. If modern makers use some other steels they probably use it due to availability or ease of manufacture as they are now made by stock removal, not forged and shaped..

1st March 2020, 06:57 PM	#5
mariusgmioc Member Join Date: Sep 2014 Location: Austria Posts: 1,903	Well Ian... yes and no. While some smiths may use it for its availability, it definitely does not explain why big, major, modern companies use it. Hanwei for example has easy access to other high alloyed steels. Its exceptional mechanical properties that makes it an almost ideal steel for swords and other bigger blades. From all I know, it has only two minuses: 1. it is rather sensitive to rusting and, 2. it is somehow harder to be worked.

1st March 2020, 07:07 PM	#6
Edster Member Join Date: Oct 2010 Posts: 408	Ian, Interesting subject. Not sure if this addresses your needs, but I found them informative. Try this one."Leaf Springs: Their Characteristics & Methods of Specification, 1912. Free Google Book. https://books.google.com/books?id=6T...spring&f=false Author says that the modulus of elasticity of all steels are virtually the same. Springs made with carbon steel "ride" the same as those of alloy steel of same dimensions. Alloy improved the resistance to repeated deflections. Other alloy additions modified other desirable qualities in manufacturing & use. While not specifically addressed in text 5160's alloy composition enhances other qualities of the carbon steel, not springiness. Steel grade standards developed first for structural steels and then to needs of the train and auto industries for consistency to engineering needs and design qualities. Sword makers in Sudan & elsewhere transitioned from bloomery irons to a good material, i.e. carbon alloy steels from railroads or lorry springs when they became available after c. 1900. I guess it just happened that what steel that made good vehicle springs also made good swords. Regards, Ed

2nd March 2020, 12:12 AM	#7
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 682	Hi Folks, An overview of 5160:https://www.azom.com/article.aspx?ArticleID=6743 A good article on how to best heat treat 5160: https://knifesteelnerds.com/2019/04/...at-treat-5160/ And where 5160 sits in terms of toughness among forging cutlery steels: https://knifesteelnerds.com/2020/02/...-knife-steels/ Ian: You could ask Larrin at Knife Steel nerds when 5160 came into generall usage: https://knifesteelnerds.com/ Cheers Chris

2nd March 2020, 08:22 AM	#8
Ian Vikingsword Staff Join Date: Dec 2004 Location: The Aussie Bush Posts: 4,203	Marius, Ed and Chris. Thanks for your thoughts and suggestions. Much appreciated. I will report back here if I discover anything useful. Ian.