Difference Between S275JR and S75JR+AR in Steel

I wouldn't think they would have the same spec. As rolled condition is just that, it might be descaled but otherwise it's a piece of steel "hot off the presses." No secondary operations have been performed, the end user of the product usually performs any heat treat or annealing process they require instead of the mill doing it. If you're dealing with a "middle man mill" they probably get the stuff AR and perform their own operations such such as sizing or grinding and perform proprietary treatments. Actually it would be size, treat, grind usually. Our just size and treat. Basically, as rolled material will be all over the place will it's internal crystalline structure. It will have the the correct ratio of elements throughout to meet a standard, that's about all you can count on. Depending on what it will be used for AR can be perfectly acceptable. For example, cutting out work piece supports for a laser or plasma cutter. Use the cheapest crap you can find (machine designer here, hence that example). If you're using for anything structural it would need to be normalized at the very least to give uniform properties throughout. If I recall correctly it's mainly used when ever you are using a heat process to cut and assemble an element. Like welding up custom I or H beams. With AR material you can heat it up to your hearts content, making processes less controlled and faster because you're going to normalize/heat treat/annealing it anyway, so why pay for material that has undergone a process when you require it to go though the same process after you've done whatever you're going to dowith it anyway. Sorry for the large paragraph, tablet really doesn't like the text boxes here. Regards, Steve.