ASTM A1008 (CR) vs. ASTM A1011 (HR)
ASTM A1008 (CR) vs. ASTM A1011 (HR)
(OP)
We use HSLAS for most of our applications due to our tradeoff criteria for applied stress, mass, cost, and formability. Currently, I would say our most commonly purchased is grade 340 or 410. So, with all of this in mind, I believe that we are mostly limited to ASTM A1008 (CR) or ASTM A1011 (HR) for the NAFTA production region.
My question, when only looking at these two ASTM standards and given the same grade 410 HSLAS-F for both, what is the benefit of Cold Rolled vs. the Hot Rolled equivalent?
Analysis of the two standards shows a 2% better min elongation percentage (18% for CR and 20% for HR), and both would meet our specifications for forming. The chemical composition limits are the same for both standards. The min Inside Radius for Cold Bending is the same for both standards (1 1/2t for HSLAS-F).
What should one expect regarding a difference regarding performance between the two standards? Would one give better forming tolerances, fatigue strength, tool wear rates, weld HAZ properties, welding/brazing distortion rates, or etc? Is the difference between the two really only the superior surface finish properties with the Cold Rolled specification? (When keeping YS and TS the same)
I appreciate if anyone had some recommendation for references on sheet steels in machine design applications it would be a great help to me.
My question, when only looking at these two ASTM standards and given the same grade 410 HSLAS-F for both, what is the benefit of Cold Rolled vs. the Hot Rolled equivalent?
Analysis of the two standards shows a 2% better min elongation percentage (18% for CR and 20% for HR), and both would meet our specifications for forming. The chemical composition limits are the same for both standards. The min Inside Radius for Cold Bending is the same for both standards (1 1/2t for HSLAS-F).
What should one expect regarding a difference regarding performance between the two standards? Would one give better forming tolerances, fatigue strength, tool wear rates, weld HAZ properties, welding/brazing distortion rates, or etc? Is the difference between the two really only the superior surface finish properties with the Cold Rolled specification? (When keeping YS and TS the same)
I appreciate if anyone had some recommendation for references on sheet steels in machine design applications it would be a great help to me.





RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
Reduced cost is an expected benefit of hot rolled steel.
Regards,
Cory
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RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
Source;
ASM Handbook, Volume 1
RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
Do not neglect the differences in formability - the ability to stamp/stretch/draw will be better and more consistent with the CR product and certain shapes may only be manufacturable from CR. R value, total elongation and n value will all be better with CR.
Fatigue properties will also be different depending on high cycle or low cycle - see SAE J1099 for examples.
RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
"There is only a small range of gauges available where the HR and CR products overlap therefore if you have a specific gauge in mind it may only be available in one form and only from certian mills. Some mills are more capable than others, such as the continious anneal line at ArcelorMittal (formally Inland) which was designed for this product."
I was under the impression that both CR and HR HSLAS are available in the standard US Gauges and also the usual metric flavors, is this not the case? Is there an ASTM norm that lists the standard available thicknesses produced?
We currently purchase what I would consider to be a large volume of coiled steel sheets. A conservative estimate would put it at about 5000 metric tonnes of one grade and thickness, and about 6000 metric tonnes of another for our high volume program. I assumed that if you were purchasing coils in large enough quantities, a steel mill would be able to make thicknesses tailored to our wishes. Again, I only can assume as I have had only limited contact with the mills we purchase steel from.
Thanks for the SAE J1099 reference. Although I only gave it a quick glance, I think it is going to be an interesting read for me.
RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
A rough estimate of the available gauges for a HSLA grade would be CR: 0.65 - 2.0 mm and HR: 1.7 - 10 mm; hence the small overlap. This due to the available power, reduction and cooling rates of the hot mills on HR product and will vary depending on width, mill etc. On the CR side the design and capability of the cold mill and anneal line comes into play. Some mills have different 'sweet spots' for gauge/width/grade combinations than others and will charge extras or no quote if you are to far outside this. See the online price books for the various mills for more information.
RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
And I agree with MSUKeith's comments, except that I think some of the newer minimills might be able to go a bit thinner on the HR (although I don't know if they do the combo of strength and desired width).
RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
I am a little surprised at the upper limit of 2.0 mm for cold-rolled HSLA. I was thinking that this type of product would be available up to 3 or 4 mm thick at least, from large producers like US Steel or Mittal. It's kind of difficult to know exactly when you are an end-user and your stamping suppliers buy everything from processors and not the mills directly.
RE: ASTM A1008 (CR) vs. ASTM A1011 (HR)
A large amount of the time there is a huge disconnect between what is called out on prints for low carbon steel automotive parts and what is actually required to make the part. This is often brought together through the cooperation of the stamping supplier, steel supplier, and Tier 1 customer. (and can take days of work sometimes)
Nick
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