1/4 Hard CRS v/s Heat treated CRS

[unp1]

We have some parts that require 1/4 Hard CRS. We are currently developing these parts in China. Our Chinese vendor is asking us if he can use HEAT TREATED CRS that has the same hardness as of 1/4 HARD CRS.

Is there any difference between these two? Thanks.

 

[limct]

As far as I know, 1/4 H CRS is hardened through cold work.
It's important to consider other mechanical property, such as formability, elongation...etc, rather than just paying too much attention to the hardness.

Best regards,
ct

 

[Goahead]

CRS is in my view an unhappy deescription because it could be Cold Rolled Steel but also Corrosion Resisting Steel.
Nothing in the text points to either one or other choice.
If it is indeed work hardened material, hardness would be reduced by any subsequent welding operation. Furthermore heat treatment, besides increasing cost, could generate distortion, decarburization, scale etc.

http://www.welding-advisers.com/

 

[swall]

Unp1--you need to clarify what you are attempting to do with this material. Will it be formed, welded, stamped, etc.? What are the desired end properties of the component? Also, do you have any indication of the chemistries of the 1/4 hard CRS vs the proposed material?

 

[NickE]

From my time on both sides of the coil steel market (on the supply, and the demand sides) That Cold Rolled Steel is just about the worst way to specify anything. (kind of like saying a cut of meat)


I would find a standard and specification and use it. SAE specs can be handy since they are relatively detailed. As ASTM can be good too.

 

[EdStainless]

Alloys are desiganted with UNS numbers, names don't count.

Mechanical conditions are spelled out in specifications, and ASTM spec number and a condition.

If you are tlaking about a stainless grade, the 1/4 hard name only appears in A666 for flat rolled material. The designation means nothing for other product forms.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[unp1]

Thanks for all your responses! Below is more info on this topic.

This is a Cold Rolled Steel for a stamping part. The material spec on the drawing is,
“.0897 +/- .002 thick C.R.S., 1/4 hard.” I don’t have much info (material properties) about the material that our Chinese vendor wants to use, but I believe he wants to use a plain low carbon steel having hardness in the neighborhood of HRB 40-50.

Thanks.

 

[NickE]

That tolerance (on gauge) is going to be tough to buy in the US market. (and may be impossible other places.) (Please dont think that I think its impossible to make, just that your average 1008/1010 cold rolling house could care less. If its within +/-5% of nominal they generally give it a pass.) (IE: .090+/-.0045 would be a more available material.)

Not that the tight tolerance and odd nominal is wrong per-say, just that its going to cost much more. I think this is a difficulty with the parts market. The guys spec. 'ing the steel are rarely if ever, familar with the steel market.





Nick
I love materials science!

 

[unclesyd]

Here are some of the numbers for C.R. Steel Strip and Sheet (1008/1010)

Sheet/Strip
[ul]
Soft max RB 65 / 55 # 5 Temper Stip
1/4 hard RB 60-75 / 60-75 # 3 Temper Strip
[/ul]

It looks like his values are within the values given for dead soft material. The only thing is that the material the vendor presents is a very low carbon grade C.R. Steel. If the lower strength of the proposed material doesn’t affect the product I see not problem.

 

[EdStainless]

Is there a carbon steel sheet spec that calls out cold worked mechanicals?
My guess is that they are a lot different from the heat treated numbers.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[unclesyd]

The spec's given with the C.R. materials are A1008A, A109, and A366. A366 is used for tensile strength.

Mean Tensile Strength
[ul] Psi
Full Hard 80,000
1/2 Hard 64,000
1/4 Hard 54,000
Skin 48,000
Dead Soft 44,000

These values are for A109 1008/1010 C.R. Strip. These values will vary slightly from mill to mill and product,
but not enough to take any special notice.

 

[limct]

If hardness is the only concern, the proposal from your Chinese suppliers maybe acceptable, but you have to review the chemical composition, it must be a killed steel in order to obtain consistent result in heat treatment.
Si<0.1% = rimmed steel
Si>1.5% = killed steel
Good luck!

Best regards,
ct

 

[swall]

Here's my 2 cents worth. The 1/4 hard cold rolled steel is a specialty product, much in the same vein as spring steel. Because of it's mech properties, it has more strength and "springyness" than a low carbon sheet steel of the same chemistry. Usually, people don't specify this stuff, except for special needs.And having been involved with a couple of products that used 1/4 hard CRS steel, I can tell you that a steel of comparable chemistry, but not work hardened, just won't work for the application.

 

[NickE]

limct--

Aluminium is also used to kill steel. In fact the Si contents you give seem more to fit electrical steels for motor and transformer windings.

 

[unclesyd]

Based on my experience and looking at my catalogues of C.R. sheet and strip suppliers there is no mention of Silicon content on AISI 1008/1010. Essential the only test that matters is the bend test and this is normally applied only to dead soft and quarter hard only.
You can get Aluminum Killed Steel in most forms but still there is no mention of AL in the analysis.