What Should the Pre-Heat temp be for A5.14 steel before you can weld?

Answer 1

while preheat is somewhat determined by material composition, spefically carbon content, is is more importantly determined by material thickness. Table 3.2 in AWS D1.1 Structural Steel give minimum preheat and interpass temperatures. ASTM A514 is not listed as it is not a preapproved material. This material is not an abnormally high carbon steel so I would consider it to fall into group II steel which requires a preheat of 32F for thicknesses up to .75 in., 50F .75 to 1.5, 150F for 1.5 to 2.5, and 225F for 2.5 and up. even if you wanted to play it safe and call it a group III material with a higher carbon content, the temps change to 50F, 150F, 225F, and 300F respectively.
That being said, unless you are welding heavy material, it is often not necessary to preheat, but if you have ever held a torch on a peice of steel you have seen that there is almost always a certain amount of moisture in steel. Moisture and strong welds never fit in the same sentence. Therefore, i will sometimes just "warm the joint up" to remove moisture.

Answer 2

Geeves-great answer overall although, your last comment about the steel containing water is off mark. What you are seeing has nothing to do with the material being porous therefore holding water like a sponge. What you are seeing during this heating process is nothing more than good ale' condensation. Heat on cold. So, whether it is "sweating the joint" or getting the moisture out of steel it is a just an environmental reaction of heat meeting cold.

Answer 3

250 min
400 is better