On 1/3/14 4:34 PM, David Gilbert wrote:
Well, my point with the cheap stuff is that you don't really know what
you're welding to. It might be part cast iron from an old engine block
for all I know, and that doesn't weld well at all. You wouldn't
necessarily be able to tell if you had a good joint or not. I used a
LOT of 60,000 PSI rebar when I built my house (ICF walls and 4,500 sq ft
of slab) and I was surprised how much variation there was in brittleness
when I bent it even for the supposedly good stuff.
But no, I'm not really hung up on the strength of the steel itself. All
of it is stronger in tension than the concrete is, and if I'm in doubt I
just use more of it. ;) I only mentioned it because I thought I saw
someone earlier in the thread question whether a welded cage was needed
for strength.
I think, as someone pointed out earlier, the welding or tying is more
about making sure the rebar stays reasonably in place when they dump the
concrete in.
Nah.. not cast iron (it's hard to roll into the bars).. probably old
ships run up on the beach in Bangladesh or India
http://www.slate.com/blogs/atlas_obscura/2013/10/02/dirty_dangerous_and_deadly_the_shipbreaking_yards_of_bangladesh.html
http://en.wikipedia.org/wiki/Alang
talk about hard manual work.. These guys resharpen their used hacksaw
blades.
I don't know if they chop the steel into "quasi-billets" and then roll
them into rebar, or if they melt it all down and then roll from there.
I suspect that however it's made, the vast majority of the stuff has
fairly casual metallurgical analysis: It rusts, it's roughly the right
weight for the size, it must be mostly iron. Details about carbon
content and heat treatment are probably not of great concern<grin>.
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