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Cold vs Hot rolled steel properties
- Thread starter Tin Man
- Start date
- Replies 39
- Views 41,789
Glenn Wegman
Hot Rolled
- Joined
- Jan 6, 2007
- Location
- Florida
MatWeb - The Online Materials Information Resource
Seems to me the tensile should be a factor of the heat treat process, not whether it is hot or cold rolled.
Seems to me the tensile should be a factor of the heat treat process, not whether it is hot or cold rolled.
We really see a difference in ductility and tensile strength on 1018 hot roll vs cold roll for our teaching labs when we do tensile tests. Cold rolled being less ductile and higher tensile strength. It is really a surprise for the students and sometimes the instructors too that they are both 1018 steel, but behave very differently.
Rob F.
Diamond
- Joined
- Aug 5, 2012
- Location
- California, Central Coast
From our supplier the cold roll is 1018 and the hot roll is A36. Have not seen hot roll 4140 but have not looked either.
Rob
Rob
Glenn Wegman
Hot Rolled
- Joined
- Jan 6, 2007
- Location
- Florida
rbent,
I had never thought about it until I saw this post.
Are you saying that if you have hot rolled and cold rolled that are both spec'd at 83k tensile, (just pulling a number out of the air) one won't be 83K?
Or are you saying that if you take 1" cold rolled annealed round, and 1" hot rolled annealed round, and heat treat them both at the same time in the same furnace that one will differ from the other in tensile?
I had never thought about it until I saw this post.
Are you saying that if you have hot rolled and cold rolled that are both spec'd at 83k tensile, (just pulling a number out of the air) one won't be 83K?
Or are you saying that if you take 1" cold rolled annealed round, and 1" hot rolled annealed round, and heat treat them both at the same time in the same furnace that one will differ from the other in tensile?
steve-l
Titanium
- Joined
- Mar 2, 2012
- Location
- Geilenkirchen, Germany
I'm not a metalurgist, but from my experience hot rolled mild steel is more ductile with less internal stresses than cold rolled mild steel. Please note that no mention of annealing was stated by the OP. Cold rolled mild is of course not rolled cold. It is rolled at the mill slighly cooler than hot roll and it will contain more internal stresses than hot roll. These stresses will be relieived during a turning operation unevenly and will cause more warping and shape change than hot roll. I have never tensil tested either, so I do not personally know if there is a difference, but it makes sense that cold roll would be higher. As a guess, after annealing there would be no difference. Further, I would guess that the stronger steel alloys would have a specific mill process associated with that alloy and hot or cold roll would not be a choice.
L Vanice
Diamond
- Joined
- Feb 8, 2006
- Location
- Fort Wayne, IN
The "1" cold rolled annealed round" will have lost its cold work-induced strength in the annealing process, or any other heat-based hardening process. Once you heat treat identical alloy steels, it does not matter whether they were originally hot rolled or cold rolled. The cold work grain structure will be modified by high heat, whether annealing or hardening.
Cold rolled steel will be harder/stronger/less ductile than as-rolled hot rolled of the same alloy. You should not expect to be able to spec the same tensile strength in cold rolled and hot rolled steel of identical alloy unless the hot rolled has been hardened after rolling. I would expect pre-hard 4140 to be stronger than cold rolled 4140 when you buy it.
That said, the main reason to use cold rolled bars is to get more accurate bar dimensions and smoother bar surface finish than with hot rolled. Cold rolled rounds are usually suitable for holding in standard collets, especially in high production lathes and parts that retain some of the original bar diameter when finished.. Hot rolled is sometimes held in special serrated or toothed collets, so the application is limited to parts where the original bar surface is turned down or is not important.
Larry
Glenn Wegman
Hot Rolled
- Joined
- Jan 6, 2007
- Location
- Florida
Sorry for the hijack...thanks for the info though!
I didn't fully understand what the OP was after, as I wasn't really sure how to compare the two in a apples to apples manner as far as tensile.
I didn't fully understand what the OP was after, as I wasn't really sure how to compare the two in a apples to apples manner as far as tensile.
The properties of 4140 Cold drawn vs. Hot are different. Agreed? I simply want to see the specs of both to compare. I am not sure how to compare them either exactly. Thus the search for a chart.
Glenn Wegman
Hot Rolled
- Joined
- Jan 6, 2007
- Location
- Florida
I use hot rolled 4140 pre hard (4142) regularly. I have seen pre-hard, normalized, and annealed, which have all been through a thermal process.
As explained above, that would negate any difference between being hot or cold rolled, which is what I had originally thought. That's were it seems a bit confusing to compare. (to me)
Are there other choices? (other than ETD150, etc.)
As explained above, that would negate any difference between being hot or cold rolled, which is what I had originally thought. That's were it seems a bit confusing to compare. (to me)
Are there other choices? (other than ETD150, etc.)
hobbyman
Hot Rolled
- Joined
- Oct 30, 2011
- Location
- Canada, BC
The problem is based on the method of specification. The SAE four digit number sustem is based on the chemical composition of the alloy. At the opposite end are grades of steel for structural purposes. A 36 is spec'd by it tensile and yield point. The chemical description of A 36 is a set of ranges that the manufacturer must be within. For example an A 36 alloy in a 36 inch beam is much different that a four inch beam. The cooling rates ae different when they come out of the rolling mill and to achieve the required physical characteristics the chemical composition is slightly different. The proper question here is what physical changes happen to a given alloy when hot rolled and cold rolled?
magneticanomaly
Titanium
- Joined
- Mar 22, 2007
- Location
- On Elk Mountain, West Virginia, USA
Hot-rolled versus cold-rolled or -drawn is a distinction that mostly belongs to mild, that is, low-carbon non-heat-treatable steels or other materials.
If a material's properties cannot be significantly changed by heat-treatment, then cold working is sometimes used to strengthen, as well as to produce closer dimension and better surface.
The distinction cold- vs hot-worked would not ordinarily be used for heat-treatable alloy steels like 4140 because 4140 would be chosen for properties obtainable by heat-treating. Even if cold-finished 4140 were desirable and available for better dimensional accuracy and surface, it would be chosen because heat-treat would be used to develop needed final properties.
Alloy steels do work-harden, but usually work-hardened properties are inferior to those obtainable by heat-treat. The Hadfield steels are one exception, as are austenitic (200 & 300 series SS)
Combinations of HT and work are also used, as in "patented" wire.
If a material's properties cannot be significantly changed by heat-treatment, then cold working is sometimes used to strengthen, as well as to produce closer dimension and better surface.
The distinction cold- vs hot-worked would not ordinarily be used for heat-treatable alloy steels like 4140 because 4140 would be chosen for properties obtainable by heat-treating. Even if cold-finished 4140 were desirable and available for better dimensional accuracy and surface, it would be chosen because heat-treat would be used to develop needed final properties.
Alloy steels do work-harden, but usually work-hardened properties are inferior to those obtainable by heat-treat. The Hadfield steels are one exception, as are austenitic (200 & 300 series SS)
Combinations of HT and work are also used, as in "patented" wire.
jitendra singh
Plastic
- Joined
- Aug 1, 2017
HR and CR steel
hello sir after reading your conversation on the difference b/w HR and CR sheet, i think you have sufficient stuff to understand the diffrentiation
can you please share any ppt or link, whatever you have
thanks...
hello sir after reading your conversation on the difference b/w HR and CR sheet, i think you have sufficient stuff to understand the diffrentiation
can you please share any ppt or link, whatever you have
thanks...
johnoder
Diamond
- Joined
- Jul 16, 2004
- Location
- Houston, TX USA
Click on Tin Man's profile and you will see he last visited the forum four months back
hello sir after reading your conversation on the difference b/w HR and CR sheet, i think you have sufficient stuff to understand the diffrentiation
can you please share any ppt or link, whatever you have
thanks...
Rahulsharma
Plastic
- Joined
- Sep 25, 2019
Both processes use rollers to apply pressure that manipulates the raw steel into desired shapes. Cold rolling manipulates the steel at room temperature whereas hot rolling involves reheating the steel to temperatures above 1,700° F.
steve-l
Titanium
- Joined
- Mar 2, 2012
- Location
- Geilenkirchen, Germany
You are incorrect. Cold rolling steel occurs at temperatures only slightly cooler than that used for hot rolling.
