Wrought Iron Properties

[dkrpink]

Does any one know the current ASTM # and structural properties for wrought iron? Doing a guardrail system for a deck and I have never designed with wrought iron before, usually just wood, steel, and aluminum. I know the old number is ASTM A753 but do not know any more than that. Thanks for any help ahaead of time.

Dustin

 

[TobyT]

AASHTO Condition Evaluation Manual has wrought iron allowable (in tension and bending) as 14.6ksi (inventory) and 20ksi (operating). Don't know the ASTM. Consider taking some coupons though to verify.

 

[swall]

Are you sure you really will be working with wrought iron? Don't know that it is even commercially available these days.

 

[dkrpink]

It is what the architect wants, however I think I am just going to change it to aluminum. But it would still be usefully to know the properties and ASTM # of wrought iron.

 

[kenvlach]

ASTM A753 is for Wrought Nickel-Iron Soft Magnetic Alloys (UNS K94490, K94840, N14076, N14080) -- definitely not the architectural material.

swall is correct -- wrought iron is no longer a (significant) commercial product. I checked a comprehensive index to ASM's Metals Handbooks -- Only one listing in the 9th edn., a chemical analysis procedure. Several listings in the 8th edn. (1973) -- mostly for microstructure, one for galvanic corrosion potential, none for mechanical properties.

All of the ASTM standards for wrought iron were allowed to lapse ca. 1972. Some of the current chemical and corrosion testing procedures still mention it.

A42- Withdrawn 1972: Specification for Wrought Iron Plates
A72- Withdrawn 1972: Specification for Welded Wrought-Iron Pipe
A73- Withdrawn 1972: Specification for Wrought Iron Rolled or Forged Blooms and Forgings
A81- Withdrawn 1972: Specification for Wrought Iron [terminology, no property data]
A84- Withdrawn 1972: Specification for Staybolt Wrought Iron, Solid
A86- Withdrawn 1963: Specification for Staybolt Wrought Iron, Hollow-Rolled
A162- Withdrawn 1973: Specification for Uncoated Wrought Iron Sheets
A189- Withdrawn 1972: Specification for Single and Double Refined Wrought Iron Bars
A207- Withdrawn 1972: Specification for Rolled Wrought Iron Shapes and Bars

From ASTM A207 (1939, re-approved 1952), Specification for Rolled Wrought Iron Shapes and Bars;

For bars (square, round, hex.) less than 1-5/8" diameter:
Tensile strength: 48,000 psi (min)
Yield point: 0.60 x TS (min) [i.e., 28,800 psi]
Elongation in 8": 25% (min)
Reduction of area: 40% (min)

Properties are slightly less for larger diameters.

Hope this helps,
Ken

 

[SlideRuleEra]

If you are interested in a historical perspective, when wrought iron was a common structural material (19th century), you can get quite a bit of technical information from the 1892 Pencoyd Iron Works book "Wrought Iron & Steel in Construction". See this page of my website for the free .pdf download

http://www.slideruleera.net/contributions.html

http://www.SlideRuleEra.net

 

[kenvlach]

There's also a good little (~100 pages) used book available:
Wrought iron, its manufacture, characteristics, and applications, by James Aston. (1st edn 1936, 2nd edn. 1941, 3rd edn. 1952). About $3 + postage:

http://used.addall.com/SuperRare/Re...or=&exDesc=&match=Y&&order=PRICE&ordering=ASC

 

[unclesyd]

Here is a supplier (UK) of Wrought Iron.

http://www.realwroughtiron.com/index.asp

 

[swall]

Unclesyd--I found that website shortly after I responded to
dkrpink's post. Very interesting. I also remember a little yellow hardbound book about wrought iron when I worked for a gray iron foundry in 1974. No connection whatsoever to gray iron castings, but it was on the bookshelf in the melt shop office.

 

[racookpe1978]

I fabricate steel (and cast iron) ornamental stair and porch railing part-time: There is no "wrought iron" really made any more, but most classic castings are available in either cast steel (modestly weldable) or cast iron (not reliably weldable). Forged parts from most catalogs are "steel" - almost all are made in Mexico or China.

I would NOT assume anything about real strength (as far as formal calc's go) for ANY (imported) steel pieces. Treat welded cast iron as "glued on" decorations: they won't fall off, but will easily break if dropped. Al parts usually have "weld tabs" if your client permits Al to be used.

Locally, I buy the ballusters (posts) and handrails as generic A-36 stock, and weld the ornamental iron to the 1/2 x 1/2 sq bar or 1/2" dia rods that go in between the upper and lower horizontal rails. Typically, most fabricators use 1x1/2 channel for the upper and lower members, but I like the look and feel of 1x1 14 GA sq tube for these members, then cover the upper 1x1 with a extruded 1-3/4 handrail.

If it is a curved rail, you can try 1x1 tubing for posts, but the rail feels much more sturdy with 1-1/2 x 1-1/2 11GA or 14GA tubing or 2x2 14 GA. Use steel baseplates or sink them 8-10" deep into concrete with grout. Don't try to use cast iron baseplates: the cast iron will fail on impact.

For commercial handrails and ADA-compliant rails for businesses, just use 1-1/4 "pipe" - it feels better than the larger 1-1/2 "pipe." Note: ONLY 1-1/2 and 1-1/4 pipe meets ADA rules for outside diameter and grasp size: don't use other pipe diameters.

Do NOT arbitrarily get Al parts or "hollow" fabricated steel parts for your client unless they specically called called for aluminum. Solid steel (forged or cast) parts and Al castings and "hollow" steel tubing have different "feels" (to the touch), and different appearances - with hollow tubing looking distinctly cheaper and rather tacky in most cases.

Best source I've found nationally is King Arch. Metals out of Dallas, Balitmore, and LA. Their casting quality, even for the pieces from China, is much better than the others I've bought from.

Your handrail/stair rail strength should be in the anchoring of the newell posts, the upper and lower handrail sizes, and in choosing the size of the newel posts. Treat the ballusters or decorative iron between the rails not as strength members but as "objects" that are needed to meet the 4" building code rules.

Robert Cook