Help me choose steel....please...

[HF]

Hi. I am searching for a low-carbon steel that will allow me to do the following. First, the dimensions of the steel bar I will be using are 1/4" by 1/4" by 48". I will be welding this bar to other pieces of steel, painting it, and then baking it in an oven at 500 degrees F for 15 minutes. I need to bake it two times to allow paint to cure. The problem I have experienced is that the steel tends deform. There are shear strains, which are causing bending and twisting of the steel bar. Could someone please recommend a steel that would stay straight through my process? Thank you very much.

 

[Rich2001]

DEFORMATION is a common problem, here are a few thing that might help.

Weld the assembly together,and then Anneal it to remove residual stress due to welding and forming. Then try your coating process. Fix your pieces so as not to induce stresses during bake.

Use as low of a heat input as possible to weld.

 

[HF]

Thanks...I don't attribute the problem much to the welding process becuase I have run bars through the oven without welding them and they still bend. I am really looking for a steel that I can buy (i.e. 1018 cold-rolled steel) that will have minimum deformation at that temperature. Annealing all the steel after the welding process will not be realisticly possible for me.

Thank you.

 

[prex]

Your problem is connected to the cold rolling procedure: a thin layer of highly deformed material accumulates on the skin of the bar, and a fairly low temperature increase may cause a stress redistribution with consequential deformation.
Assuming you may not heat treat the bar (and straighten it) before any other operation, I suppose (but no direct experience, only thoughts!) that an austenitic material (stainless steel) would behave better as it is less prone to hardening, softer and better resisting to temperature (however the heat expansion coefficient is higher and that makes worse).

prex
motori@xcalcsREMOVE.com

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You might want to try stress relieved steel

 

[arunmrao]

Please consider stress relieving the steel before welding. Alternately austenitic grade stainless steel can be the answer.
Arun Rao

 

[sbi]

How abought a well ventalated room ans use a fast flash acrykic enamel??

 

[manian]

Shape being square might have a tendency for uneven distibution of residual stresses. May be you can try with a round bar?

 

[MIKEMGB]

Try using hot rolled steel instead of cold rolled as it has less stress in the bar

 

[pittguy727]

If you want just a replacement metal, you can try Hastelloy or inconel products, they are normally used for corosion, but have great heat properties too.

 

[awol]

Choose a vendor to hang your weldment vertical while baking.

 

[Snork]

Caution - both the autenitic stainless steel and the nickel based alloys that are suggested require filler metal on the welds which will balance the chemistry. It would be best to stay with a low carbon alloy like you want. But it would be advisable to stress relieve the part prior to painting. Also the comment about using hot rolled rather than cold rolled is sound. Is it possible to rack the part for the paint drying in such a way as to minimize warpage? I've seen racking correct problems with warping heat treated parts. Just a thought

 

[dvd]

I wonder if you are using radiant heating in your oven while controlling the temperature by the air temperature. You may very well be heating the steel to temperatures in excess of 500° F, and thus the elastic modulus of the steel can be significantly less than 2.9x10^7, which would explain the bending.