Road Cycling - Steel numbers: Translation please?

I see things like 530 or 853 or other type of numbers to signify steel frame materials. Is there some place where the difference between these numbers is described? Same is true for aluminum: 4's and 7's etc. I'm not looking for a bike, but I'd like to understand what all these things mean. Anyone have a link?

Look for the Reynolds USA site (sorry I dont have a link) for the meaning of the Steel numbers. For the Aluminum bikes I believe the good ones are 6XXX and the cheap ones are 7XXX - I think it is something to do with the ease of (or lack of need to do) heat treatment after welding.

www.reynoldsusa.com has descriptions of all the Reynolds tubing out there.

The aluminium numbers. First there are hundreds of "standard" aluminum alloys these standard alloys are numbered example 6061-T6, the 6061 is the alloy formulation and the T6 is the leval and type of heat treatment. These are the basic direct answers. But before I go any further, how in depth do you want to get, and do you already know or want to know what all the common strength properties mean and how they affect a matierials characteristics? Those properties are: ultimate tensile strength, yield strength, fatigue strength/resistance, modulus of elastisity, and the difference betwen stress and strain. I'll explain the terms if you wish, but the mechanics section may be a better place to continue discuing this.
Some of these are better for cold working and gain strength with working others are better for heat treating and others are better for casting, some expand and contract less when heated and cooled.


Aluminium's range of properties can be found in an impressive array of commercially available alloys. The composition and logic of those alloys are regulated by an internationally agreed classifications system or nomenclature for wrought alloys and by various domestic nomenclature schemes for the casting alloys.

The wrought scheme is as follows. Each registered alloy is described by a four digit number, with a further letter and number indicating the temper, or condition of the alloy, For example, 6082-T6 is a medium strength grade based on the aluminium-magnesium-silicon family, in the fully heat-treated condition.

The classification provides for:-

1XXX Aluminium of 99% minimum purity
2XXX Aluminium-copper alloys
3XXX Aluminium-manganese alloys
4XXX Aluminium-silicon alloys
5XXX Aluminium-magnesium alloys
6XXX Aluminium-magnesium-silicon alloys
7XXX Aluminium-zinc-magnesium alloys
8XXX Miscellaneous alloys, e.g. aluminium-lithium alloys

Alloys fall into two main groups. The work-hardening alloys, where strength is achieved by the amount of "cold work" applied to the alloy, e.g. by rolling, and heat-treatable or precipitation hardening alloys, where the strength and properties are achieved by heat treatments of varying complexity.

Here are some links to Columbus tubes:
http://www.columbustubi.com/english/alluminio/index.htm
http://www.columbustubi.com/english/acciaio/index.htm
These cover aluminum and steel tubes. On the left are links to particular Columbus tubesets (Zona, Airplane, Thron, Starship, etc.)

Here is a good start.
http://www2.sjsu.edu/orgs/asmtms/artcle/articl.htm
Then go here:
http://www.eastonbike.com/TECH_FAQ/tech_techbull.html
This is good also:
http://www.henryjames.com/tubing.html

You can look up individuasl tubingmanufacturers for more info. Also 7000 series is the higher end tubing not the 6000 series stuff.

I see things like 530 or 853 or other type of numbers to signify steel frame materials. Is there some place where the difference between these numbers is described? Same is true for aluminum: 4's and 7's etc. I'm not looking for a bike, but I'd like to understand what all these things mean. Anyone have a link?

Someone asked me in a PM about the differences between 4130 cro-mo, 853 and Ox Platinum. Here's my reply.



First of all 853 and Ox Platinum are brand names while 4130 is a technical SAE/ASTM designation. A popular brand name of 4130 steel would be something like Tange Prestige, Reynolds 520 or Ritchey Logic.

Reynolds 853 and True Temper Ox Platinum is actually a cro-moly steel with a sprinkling of vanadium instead of more common manganese. Although these air-hardened steels are materialwise stiffer and stronger than standard 4130 cro-moly, they are often shaped into tubes tweaked to provide more plushness in the middle of the tubes and make better use of the material's compliance.

As far as a website where you can look up materials properties, you might try doing a google search for ASTM. You should also be able to find information on aluminum alloys. 6000-series and 7000-series also refer to SAE/ASTM designations which in turn refer to the alloying percentages in the metal.

Aluminum designation abide by the following standard.

First digit
No alloy
Copper
Manganese
Silicon
Magnesium
Magnesium and Silicon
Zinc
Some other alloy
Unused


Second digit = purity level

Third and fourth digits = percentage above 99% for 1000 series alloys (unalloyed)

A different meaning is applied in 2000-9000 series because the alloying percentage is often much greater than 1%. For 2000-9000 series alloys, the third and fourth digits are allocated to particular compositions of different alloys. This was done randomly and as new ones are added, they are registered thus there is no particular rhyme or reason to the third and fourth digits to anything but the 1000 series.

You may also see a T appended to the alloy (ie 6061-T6). The T designation indicates tempering and the numerical value indicates the hardness of the resulting tempering process.

Here's a quick overview, without getting all Jingoistic -

Steels. 3 basic categories -

4130 or Cromoly - A Steel alloy of Chromium and Molybdenum. There are various different grades of this, but it's kinda the basic performance metal. Common brands/models are Columbus Gara and Thron, and True Temper Versus. Sometimes these materials are heat treated, which improves their mechanical properties, such as with True Temper Versus HT.

Micro-Alloyed steels - Sometimes using 4130 as a base, some other elements such as Niobium, Manganese and Vanadium are alloyed with it to improve the grain structure of the material, therefore improving it's mechanical properties or post weld characteristics. Columbus Zona is probably the best well know example.

Air hardening or Thermophillic steels - These are alloys usually specifically designed to have certain reactions to the heating TIG welding emparts on a frame. The material is designed to withstand or improve at the Heat Affected Zone (HAZ). Some examples are 853, OX Platinum, and Foco/Ultrafoco.

Now, all materials are not created equal. There are many ways to improve a material that are not simply a matter of alloying it, such as heat treating it or working it mechanically by work hardening, drawing, swaging etc.

Aluminium - 3 major bike relevant categories ( Capsicum has a good rundown on these )

2000 series alloys - Some handlebars are made from alloys in this category. It's high strength but not weldable.

6000 series alloys - Probably the best known, 6061 is a typical alloy used in bike frames. It requires heat treating to T6 to achieve its optimal mechanical characteristics.

7000 series alloys - There are 2 common types used in bikes - 7005 and 7075. Most bikes these days are made from 7005, because it typically does not require precipitation heat treating - often artificial aging will suffice. 7075 is what's used in most CNC'd parts as its a very high strength Aluminium, but is not weldable.

I hope that helps you out. I'm not a materials expert - I tend to know a little about everything - so i could be wrong or vague on a few points, but that's all the important things that you need to know. More often than not, names or numerical designations used by companies are simply brands. Also, it's not like you get a choice in materials really. If you've got X ammount of dollars to spend on a bike, chances are all your options will be made out of the same stuff anyway, so don't get too hung up on it.

If you want to get more in depth, Capsicum seems to get into it, so I'd suggest you hassle him :)

Wow, I was really just looking for x = stronger/lighter/more flexible than y, but all this stuff is great. Thanks!

7075 is stronger than 6061, but 7075 has a shorter fatigue life and tends to be more brittle than 6061. 6061 also has very low and slow crack propogation. These are why personal aircraft are made more from 6061 (less regular maintanence) and commercial use more 7075 -they have a defined maintainence schedule where the inspect and replace things before they fatigue. Unless your hawaiian then your 7075 skin reaches the end of its fatigue life before everyone else and the top rips off :( .(more up and down between islands = more work cycles) Yes they learned from that mistake.