Properties of A36 Steel at -40¦C Ambient 1

[bseymore24]

Hi all,

Could anyone provide me with some insight about how A36 structural steel would behave at -40°C ambient?

To provide some background, our goal is to lift a piece of machinery weighing 5 tons using three strategically placed lifting lugs. So my main concern is, if we were to have these lugs fabricated from A36 steel, would the strength of the steel be compromised at all at such a low temperature? And if so, could you provide any suggestions of what material the lugs should be machined from?

 

[TGS4]

That is likely at an ambient temperature below the ductile-to-brittle transition temperature. Therefore, the steel will behave in a brittle manner - especially if it is subjected to any impulse loading.

It's not an issue of strength, but of toughness/ductility.

Try a steel that has been normalized...

 

[fegenbush]

The strength of the material is not likely to be affected, however, the toughness would suffer considerably. The use of A36 at these temperatures could lead to brittle fracture. If A36 is to be used, the manganese content should be limited to 0.80%-1.20% by heat analysis and the material should be impact tested in both the longitudinal and transverse direction.

A simpler solution would be to use a low temperature carbon steel such as A516 Gr 60N (if plate material) or austenitic stainless steel such as 304.

 

[weldstan]

A-36 can be purchased with appropriate toughness. You'll need lots of luck to find a small piece for lifting lugs. Standard A-36 structural shapes are expected to have Charpy absorbed energy values < 5 ft-lbs @ -40. As others have stated, it will be brittle and the UTS will approach that of the Yield Strength. If you are welding the lugs to the item to be lifted, brittle failure is quite possible depending on the dynamism of the lift.

 

[racookpe1978]

And THEN he burns/cuts/plasma cuts or bandsaws (?) that chunk of A36 into his lifting lug shape, then welds it unto the vessel with many weld passes ....

No good guess at all about what the actual final material properties are unless he stress relieves the lug and vessel very, very carefully after all welding.