ASTM A588 steel

Date 03-15-2007 15:14

Last week we were having trouble finding a particular W shape in a size we needed. We had steel ordered for a while but delivery was not going to happen for a particular W section. That problem has since been cured. But in the mean time, a question arose.

Job specs were for ASTM A992, which is pretty much all we ever use. Our purchasing manager had found the correct size in ASTM A588. Management wanted to know could we use it instead of A992. AISC and AWS D1.1 rules. Questions arose concerning a) is it OK to substitute in place of A992 (subject to SER approval)?; b) weldability (I see Table 3.1, note b in D1.1; we typically use FCAW E71T1); c) WPSs, my question because they certainly did not think of it; d) coatability, since it is a weathering steel, will coating behave differently on it compared to rest of structure made from A992 (John? your NACE class help here?)? I have little to no experience with A588. Since we have never used it, I don't even have the ASTM standard for it. May have been used many a year ago in a bridge shop, but if so, my hard drive has long since deleted that data.

This is a mental exercise now so I (we) will know the answer next time. Any feedback is welcome.

By CWI555

Date 03-15-2007 19:29

I would be surprised if the switch is allowed. I don't know all of your particulars, but there are some noticable differences in the two specs:

A992 states open-hearth, basic-oxygen, or electric-furnace. Additional
refining, by electroslag remelting (ESR), vacuum-arc remelting (VAR), or ladle metallurgy furnace (LMF) further, the steel is required to be killed.

A588 states open-hearth, basic-oxygen, or electric-furnace and the steel shall be made to fine grain practice. The open ended statement of fine grain practice does not always mean killed.

A992 has a specific tin allowance of <2% while A588 has nothing of the sort

They vary for chemical allowances as well.

A992 has a higher carbon, differences in Maganese, depending on the grade of 588 a lower allowance for silicon, depending on the grade a lower nickel allowance, in short several chemical allowance differences.

Depending on thickness, for the most part A588 has lower yield strength and other differences in mechanical processes.

I am not a coatings expert so I cannot answer that part, but judging from the variances in manufacturing, chemical, and mechanical tolorances and methodology, I would not suggest making the substitution.

By HgTX

Date 03-19-2007 19:50

It depends on your application. If the design relied on the particular yield-to-tensile ratio that is required in A 992, then you can't use A 588. For most structural applications, though, they're fairly equivalent. If old A 572 would have sufficed, then A 588 ought to be fine.

Hg