Cooling metal in the open air has a limit to the rate of cooling and for this material its slower than the rate to make it brittle.
Ron ---------- Original Message ---------------------------------- From: "Ron Freiberger" <rfreiber...@swfla.rr.com> Reply-To: rfreiber...@swfla.rr.com, KR builders and pilots <kr...@mylist.net> List-Post: krnet@list.krnet.org Date: Thu, 1 May 2003 22:08:42 -0400 >Mark Wrote; >So, my point is, no matter how you make the holes in your WAF's, whether it >be waterjet, laser cutting, drilling, or shooting a bullet through them, >there is no reason to worry about the heat affected zone, or losing the heat >treatment. By setting these on your workbench when you are done making a >hole and waiting a bit, you have effectively normalized the part.. > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >This isn't right. If you local heat the part and it cools quickly by >conducting heat away from the localized zone, it will be brittle. If you >heat the entire part and let it cool slowly, it will be near the normalized >condition, but slightly softer. Normalizing is a careful process. The >material can be heat treated to stronger than normalized condition. >Normally, gas welding as fuselage will give softer condition near the joint, >but that's OK, 'cause the bending moments are usually out in the middle, >4130 is a very versatile material, but casual handling yields casual >results. > > >Ron Freiberger .. EAA Tech Counselor 4125 >mailto: rfreiber...@swfla.rr.com > >-----Original Message----- >From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On Behalf Of >Mark Youkey >Sent: Thursday, May 01, 2003 1:40 PM >To: KR >Subject: KR>Reattack on WAF's, and Antenna website > >The previous discussion a few weeks ago about WAFs, and laser cutting, heat >treating, etc, didn't set well with me. So today I finally found out why. >As it turns out, 4130 steel air normalizes. That means that if you heat it >up, and then just let it sit out to cool down, you have returned it to a >normalized state, and have done the heat-treating yourself. No wonder it's >a cheap process....but paying for that at all sounds like you are >overpaying. > >So, my point is, no matter how you make the holes in your WAF's, whether it >be waterjet, laser cutting, drilling, or shooting a bullet through them, >there is no reason to worry about the heat affected zone, or losing the heat >treatment. By setting these on your workbench when you are done making a >hole and waiting a bit, you have effectively normalized the part.....and >done it cheaply. Nice, huh? Just don't throw water or oil on it...that >will screw up the cooling speed and give you potentially unwanted >results--hence "Air Normalize" > >Here's a good website that talks about 4130 steel. >http://www.eaa1000.av.org/technicl/4130.htm > >http://www.eaa1000.av.org has links on it to great pages, including >"Technical Articles" where I found the steel article. > >As promised in my subject line, >http://www.eaa1000.av.org/technicl/antennae.htm is a good article on antenna >installation. Hope this helps. > >Whoever out there is a member of Chapter 1000, great website. > >Mark Youkey >myou...@cox.net >Okalhoma City_______________________________________________ >see KRnet list details at http://www.krnet.org/instructions.html > > >_______________________________________________ >see KRnet list details at http://www.krnet.org/instructions.html > -- Ronald R. Eason Sr. Pres. & CEO, KCMO Office J.R.L. Engineering Consortium Ltd. 816-468-4091, Kansas City, MO. Jim Eason V.P, 770-446-1291, Atlanta, Georgia Web Page: www.jrl-engineering.com --
