I have an application in which I need to take a piece of C 1045 Hot Rolled. 3/4" diameter (Rockwell of C16 from the chart) or 3/4" diameter C 1045 Cold Drawn. (Rockwell of C15 from the chart) and heat it red with a torch to bend it around a fixture to obtain a 4-1/4" radius and then let it cool ,then and after it cools stitch weld it at the bottom every 18-24" to a piece of 3/4 " thick flat plate of steel to hold it in place.
My question is if I use the C 1045 H.R. in this application, will I lose the hardness of the material (C16) when I heat it since it was hot worked anyway when it was manufactured?
If I use the C 1045 C.D. (C15) steel in the same application will its' hardness be changed any differently beacuse it was cold drawn during its manufacture?
I want to end up with the highest hardness value when finished and I am not sure which would be best in this application.
Because of the relatively high carbon content of the 1045, you will likely find that the pre- heat before bending will harden the steel, especially if allowed to cool quickly, and that welding it will result in brittle welds if it is not pre-heated and cooled very slowly. If you weld it to a low carbon plate, the chance of cracking increases if it is not cooled very slowly. Therefore, pre-heat, bend, cool very slowly. Pre-heat everything, weld, cool very slowly. You should be OK. If you need higher hardness when you are done, you can locally heat and then quench the areas of the 1045 that you need to be hard. Glenn.
1045, being a medium carbon steel will need preheat/post heat to weld. All the heat affected zone from welding will remove the original "hardness" properties. May be softer, may be harder.
Your heating it up red hot will most likely make it approximately normalized, which also may be harder or softer than when you bought it.
In the mass effect data in the E.M. Jorgensen catalog for similar 1040, the Brinell hardnesses are given as:
As Rolled 201
Considering what you are doing to the material, it should make no difference at all whether you use HR or CR.
Hard is a relative term. Most users start referring to hardened steels around 300BHn, all the way to 739BHn (roughly 32 to 65HRc).
will I lose the hardness of the material (HRc16)
1045 is produced in the 'soft' condition (16Hrc) so it can easily be machined. It is then hardened for greater strength -- the as-quenched hardness is greater than 55HRc. If your main concern is hardness, you'll want to heat treat after fabrication.
One note of caution when welding any steel with over 25 carbon points - the temperature of the welding process acts to locally harden the material. Each of your stitch welds may caused spot hardening as the weldment rapidly cools, an unintentional 'air quench'. To avoid this:
preheat both the flat & the round to 300*F,
use the process that inputs the least amount of heat (GMAW would be first choice)
let the part slow-cool in still air.
After the part is cooled to room temp, shield the base (where welded) using either Heat Stop Paste or a wet towel. You can then locally heat treat the area of the round stock that requires greater hardness.
If this is used for a wear or strength application, the 1045 must be heat treated. I work with tons of 1/4" M1044 plow steel flat bar. It gets punched, chopped, countersunk and formed before being heat treated to a spring temper.
In the as delivered condition the material will gouge and ding. It is pretty soft relatively speaking.
There is no advantage to using the cold drawn 1045. The cold drawn will be about the same hardness as the hot rolled after heating red hot (1500 F).
You're right on the hot rolled. It will be about the same hardness after the bending. Hot rolling finishes around 1500/1600 F and the cooling rate is similar to air cooling you'll be using.
If you need the rings hard, quench and temper them after forming. They will have more of a tendency to crack in the HAZ once they are Q&T'd. Also, welding circles can make some high stresses. In addition to the advise above, weld from the closed ride of the ring to the open side. That will allow thing to move a little better.
Thanks for the input.
I am missing something here.
1045 Hot-Rolled with the proper equiptment can be bent cold with no heat involved.
Water quench after red heat is loosing me.
Out of curosity, what does it cost to contract out heat treatment, say for a pair of 1.250" rods 12" long, I've got a similar problem coming up, where I need some long pins with knurled or welded ends and lots of shear strength.
I don't meant to hijack the thread.