heat treatment of SAE 4140 steel

[Amber H-B]

I was wondering if anyone can verify or ? my findings. Have found in Lincoln's Procedure Handbook of Arc Welding (6.1-29) that SAE 4140's preheat, postheat, and interpass temps when welding with lo hydrogen electrodes is 600-700 deg F for 1/2-1" stock. Is this accurate? What are pre- and post- heat times for 4140 using a rosebud? Sorry for so many questions. Still a student and beginner. Still so much stuff to learn.

Thanx for ANY replies.

Amber H-B

[Danco]

there's no set "time" for allowable pre/post heat. your best bet is to go to a welding store and buy a "temp stick" for that heat range. as your heating the steel, touch the stick to the metal. It will melt when correct temperature is reached.

[Jerry]

I have welded a few 4140 aluminum casting mold dies in my shop. I only heat up a bit usually enough to get the chill out. I also weld these with mild steel filler by mig gun or tig welding.

[Mike Sherman]

4140 is a HTLA steel and preheat, interpass and postheat are important. My ASM Handbook shows the suggested preheat at 450 F to 550F, Lincoln is a trusted source and I would not hesitate to follow their suggestions, even if there is a slight descrepancy in temperatures. A temp stick or a thermometer of some sort is essential for accurately maintaining your temperatures. Try to heat the steel up to temperature one or two inches from the area to be welded.