Tempered Steel

[FNB8812]

I have a piece of alloy-steel round bar(4140) the dimension are 1/2 diameter and 4 long and the steel has been heat treated and tempered to 40-45 Rc I am heating up the end of the steel bar to about 1500 degrees for 10 seconds. My question is when I do this am I effecting the heat treatment or changing the properties of the steel in any way and is there a recommendations for cooling?

 

[dhengr]

The short answer is YES you will “effecting the heat treatment or [and] changing the properties of the steel” in the immediate area of your heating. Now, define ‘immediate area.’ How and why are you doing this heating at the end of the rod? You may get the end of the rod up to 1500°F and hold that temp. for about 10 seconds, but you had to have been heating the rod for some period of time, and then it will take time to cool, and during that time the entire length of the rod had also been conducting heat. Any rapid cooling will harden and change the metallurgy too, maybe drastically in a small length. Does the whole rod need the heat treatment and tempering treatment, or can the rod be softer near the heated end? Can you do your heating, and then temper the rod where you need it? What does the chemistry of 4140 really do under these temps. and heating processes? I would talk with my favorite heat treater, or metallurgist, about this problem.

 

[Tmoose]

http://www.nhml.com/images/resources_NHML_embrittlement_steel_fig1.gif

10 seconds >>may<< not be enough to reach full tempering effect, and who knows about the cooling rater, but 1500 F is up there