Are angles really only 36ksi?

[swearingen]

Back when the switch to 50ksi for wide flanges was occurring, it was widely known that the mills were rolling only 50ksi wide flanges, but stamping them as A36 and A572 for 36ksi and 50ksi requirements, as needed.

I have some just-fabricated new steel angles that need to be modified. Does anyone know if the mills routinely roll angles at higher grades, but call them A36? I'm curious whether I have a chance to take advantage of some higher strength. If there's a decent shot, I'll send off a coupon to be tested...


-5^2 = -25 ;-)

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[WinelandV]

There's a high chance. We've been able to get mill certs for the angles showing the dual certification. Thus allowing us to use 50ksi to get some projects out of a bind within the last few months.

As the good advice says, you'll never know until you ask.

 

[dauwerda]

It is my understanding that A36 often has yield strengths when tested that are int the 40-50 ksi range (not the same thing as if it were dual certified as both A36 and A572 as you are talking about). Can you get the mill certifications for the angle you have from the supplier?

 

[MotorCity]

To add to what dauwerda said, ASTM A36 does not impose a maximum yield strength. That is what allows it to be dual certified since it meets the minimum yield strength requirements for A36 and A572.

We specify 50 ksi for all angles and channels. It results in smaller members not governed by deflection and have not had any issues procuring that steel.

 

[jayrod12]

Up here in the great white north someone has told me that they've pretty much stopped fabricating anything to the 300W (44ksi) and all of the new stuff meets 350W (50 ksi). But when in doubt, if they're newly fabricated, just ask for the mill certs.

 

[swearingen]

Unfortunately, I didn't have time to get the mill certs, as this was a field problem that needed fixing quickly. Thank you all for your replies. As a bonus, I'm including the official response I received from AISC:

"I have addressed your question below in red:

Mills in the past rolled 50ksi wide flanges and stamped them both A36 and A572 because they met both specs. Is this true for angles today? I am not sure, but I suspect that there are dual- (and perhaps even multi-) certified angles on the market today. Note that dual- and multi-certified wide-flange sections are still available. If you want to purchase a wide flange section certified to ASTM A36 I believe this is possible. The section will also likely satisfy A572 and A992.

Do angles rolled today have a consistently higher yield than 36ksi? Yes. Steel sections have to satisfy the minimum strength requirements of the ASTM standards, so all sections will be produced “to have a consistently higher yield” than the minimum specified. If this were not done the natural variations in the process would require producers to scrap an unacceptable amount of material it produces. Not all angles produced today will have yields equal to or exceeding 50 ksi.


The following article states:

“The preferred material specification for these shapes is in transition. ASTM A36 (Fy = 36 ksi, Fu = 58 ksi) is now only slightly more common than 50-ksi grades like ASTM A529 Grade 50, ASTM A572 Grade 50, or ASTM A992; each of these 50-ksi grades has Fy = 50 ksi and Fu = 65 ksi for these shapes. The availability and cost-effectiveness of M-shapes and S-shapes in grades other than those listed should be confirmed prior to their specification. M-shapes and S-shapes with a higher yield and tensile strength can be obtained by specifying ASTM A529 Grade 55, ASTM A572 Grades 55, 60 and 65 or ASTM A913 Grades 60, 65 or 70. Atmospheric corrosion resistance (weathering characteristics) can be obtained by specifying ASTM A588 Grade 50. These and other material specifications applicable to M-shapes and S-shapes are shown in Table 2-4… The preceding comments for M-shapes and S-shapes apply equally to angles.”

https://www.aisc.org/globalassets/m...2018/04/areyouproperlyspecifyingmaterials.pdf

Please let me know if you have any further questions.

Larry S. Muir, P.E.
Consultant
American Institute of Steel Construction
866.ASK.AISC

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This document has been prepared in accordance with information made available to the American Institute of Steel Construction at the time of its preparation. While it is believed to be accurate, it has not been prepared for conventional use as an engineering other information or construction document and should not be used or relied upon for any specific application without competent professional examination and verification of its accuracy, suitability, and applicability by a licensed engineer, architect or other professional. AISC disclaims any liability arising from information provided by others or from the unauthorized use of the information contained in this document."



-5^2 = -25 ;-)

http://www.eng-tips.com/supportus.cfm

 

[pperlich]

All the angle we buy comes certified to multiple grades, of which A572-50 is included.

 

[jdonville]

If in doubt and it's critical, send a coupon and do some tensile tests in a lab.

 

[skeletron]

Watch out with using coupon test results; they may only be used to classify the steel to a certain specification. The minimum values for strength for the specification would still need to be used (not the coupon test results) (Cl. 5.1.2 S16-14). Angles can be double certified, but you have to check with the mill.

 

[271828]

I've heard that AISC will start using 50 ksi for angles in the next Manual. Maybe for plates also.

 

[bridgebuster]

I'm surprised you can't get a mill cert. Perhaps I'm spoiled by working on DOT projects; ,mill certs have to come with the delivery otherwise no payment. Money talks.