Yes, you can have too hot a tip...which melts ties, and causes the PCB ties copper cladding to come off, and carbonizes your paste flux sometimes.
I'm going to get into how I do my turnout/track soldering, which entails much more than just soldering iron temperature since it appears from your post you're new at soldering metal model structures.
Soldering turnouts and track is a bit different than soldering for electrical/electronics. Solder and flux for the electrical stuff is different than what you should be using for building brass/NS/bronze/copper structures, which is what turnouts and track are...structures...models of prototype railroad structures.
Yes, since the rails carry electronic and electrical currents and signals, they are also electronic.
I've built hundreds of N-scale turnouts using the PCB method, starting in the early 1980's because I couldn't stand installing toy-like turnouts on my first Ntrak modules, sooo...I had to learn how to do it by looking in various magazines for articles, the most helpful one being how to build Code 40 turnouts by Larry Kazoyan and Gordon Odegard (February 1976 Model Railroader). The article illustrated two different methods of attaching the rails to ties with Gordy Odegard's method being to solder them to PCB ties instead of using Goodyear Pliobond Cement. Needless to say, Fast Tracks hadn't been thought of yet.
It's late and I'm not going to get sidetracked too much here, but I am a huge proponent of using silver bearing solder for turnout/track construction. I use 96/4 Tin/Silver solder, which is 5 times stronger than electronic solders, and melts at 460 deg F (237 deg C)...as opposed to 60/40 Tin/Lead electronic solders which melt at 430 deg F (221 deg F)...only 30 deg F hotter than Tin/Lead
Also, the silver bearing solder has much less carbonization, has less of a fillet, is brighter and doesn't have destructive oxidation like Tin/Lead solders sometimes have...especially when painted over.
Of even more importance is the exclusive use of the best flux for PCB turnout construction made....
Superior No. 30 Supersafe Soldering Flux. It used to be available in both a liquid and a gel, but the gel turns into liquid after a few years, so now I just order standard strength liquid.
Let me emphasize that this flux will revolutionize your soldering...is self-neutralizing from the heat of your solder joint so it's not absolutely necessary to wash your turnouts to clean off any excess flux. I wash mine when they're finished anyway before installing them on my layout, but...on the few turnouts I've had to repair in place, I don't wash them, and they don't corrode after painting...and some of my hand-built turnouts are over 3 decades old.
As has been already stated, both the solder and flux are available here:
https://www.hnflux.com/page35.html as well as applicators and other handy things for soldering.
As far as soldering techniques are concerned, I'll tell you what has worked for me in the past using the most basic of soldering equipment...and worked very well.
Here's what I used for a couple of decades and for hundreds of turnouts:
(1) My soldering iron was (and still is) an old Realistic (Radio Shack) 35W iron with a wedge tip...nothing special, and I still use it for tinning purposes.
(2) A soldering stand with a damp sponge to clean my iron's tip
(3) A little tin of tinning compound to melt on the tip of my iron's wedge tip before each and every soldered joint
(4) Spare wedge iron tips
However, I've used some of my train buddies' fancy electronic temperature controlled digital irons, and as long as the tip is clean and tinned, I do equally well with a more expensive soldering outfit with a smaller pointy tip.
My techniques are simple.
(1) I wipe my rails down with a paper towel that is wet with rubber cement thinner (Heptane...known by the name Bestine). This removes most oils and greases that will inhibit making a perfect solder joint.
(2) I wipe my PCB ties with the same stuff for the same reason.
(3) I rub the tops of my PCB ties with a pencil eraser...attached to a wooden pencil. This easily removes most of the oxidation.
(4) I attempt to keep my greasy/oily fingers off of the surfaces that will be soldered to each other.
(5) The silver solder is .031" in diameter, which is a bit large...so I flatten about 1/2" of it with my flat-nose pliers and split it down the middle with my Xacto knife...forming little rabbit-ears and use these rabbit-ears instead of the full-round solder. This makes a much more precise method of getting just enough solder into the joint so you have much fewer globs and blobs to clean up.
(6) My iron's tip is ALWAYS clean and covered with a bright silvery tinned tip before EVERY soldered joint.
(7) I apply a small amount of Superior No.30 Supersafe Soldering Flux where when I position both parts to be soldered, so it wets both parts.
( 8 ) I like to apply the heat to the opposite side of the rail foot...touching both the top of the PCB tie's cladding and the rail simultaneously...and put the smashed, flattened and thinned silver-bearing solder to the opposite side of the rail in the same place as the iron's tip is on the opposite side of the rail...PFFfft!...the flux evaporates, the solder melts, and the iron's heat draws it under the railfoot towards the iron's tip. When I see a thin fillet of solder right where I have the iron...I remove the iron, and let the joint cool. This can be done very fast and precisely with just a little practice.
(9) If you get blobs and globs of solder that you're not happy with on some joints (it always happens) I use a fine de-soldering copper wick to remove them...or if they're not too big, I'll heat them up and wipe them across the top of my PCB tie..basically tinning the top of the tie. You won't see this after you paint, weather and ballast your track.
For more precision, since the turn of the century I use my 250W (turned waaay down) American Beauty Resistance Soldering Station, holding the rail in place with the tweezer tool...applying both flux and solder the same, stepping on my power foot pedal...watching the solder melt and run to both sides...get off the pedal, continue to hold the rail in place with the tweezer a few seconds until the joint cools...then go the next joint. No tinning or cleaning of iron tips and being able to hold, solder, hold and let cool much more efficiently. If you're planning on building a lot of turnouts, I'd think seriously about budgeting for one of these.
So...that's about it. I could get into how to cut gaps in your PCB ties so they disappear after painting and weathering, how to make your frogs look better, how to hinge and make your point rails look more realistic...but the advice in this post should solve your soldering problems if you follow it exactly.
Photo (1) - A little monolithic turnout construction at my bench using these materials and techniques:
Good luck and have fun!
Cheerio!
Bob Gilmore
