S&M_PBR_007

i was watching a show today and the were talking about 4130 chromaly and they said that it before it was heat treated it was softer and easier to work with and then you would like bake it in a special oven and heat it up and it would be stronger than it was. i was wondering if the did this with bike frames? like S&M. Thanks

mude

yes.

ghostdncr

Yep, and that's what makes 4130 such a ***** to weld! The heat effected zone around the weld gets very hard and brittle and must be normalized before you can ride it. Isn't that why the vast majority of steel frames are brazed (lower temps)?

Brian

The vast majority of steel frames are not brazed, so no.

S&M_PBR_007

r u talkin about chromally frames

hypersnazz

Many heat-treated air hardened chrome-moly steels actually get stronger as they're welded (Reynolds 851, True Temper OX Platinum, to name a couple), further nullifying arguments for brazed joints in this day and age.

ElectricTape

Ding Ding Ding, hypersnazz got it.

S&M_PBR_007

so does that mean that 4130 also get stronger when it is welded? Thanks

dooley

4130 loses some strength when welded, but it doesn't get brittle, it gets softer. And you can't heat treat a frame post-welding because it will distort.
Don't bother with fancy air hardening tubes, they just trade off elongation for UTS, which is fair enough for MTBs and the rest, not so for BMX.

S&M_PBR_007

so when your done welding 4130 you have to heat treat it to normalize correct? Thanks

jackmcjack

who cares its strong and light you've got a bike now go ride it

dooley

Heat treatment and normalizing are 2 different things. Basically when you weld a frame you leave it, smaller parts, including forks and bars these days can be heat treated.

https://www.moldmakingtechnology.com/...es/110002.html

mude

dooley. thanks. i knew they heat treated smaller parts so i assumed they did it on frames to.

S&M_PBR_007

on my pbr is that the chromally the same gauge? Thanks

alspec

I ran into this site and just had to answer someone..

Please pass this around to all your associates

I started riding serious bikes in the 1960's (Gitane) and still have a Raliegh Team bike - Reynolds 531 frame.
I have been in the Metals Industry running an Aerospace Division for 27 years working with the largest
manufacturers in the US.

First -

Heat Treating is a genaric phrase and never used by a professional in the metals industry.

Heat treating covers "ALL" thermal processes

You : Anneal * Stress Relieve * Normalize * Normalize & Temper * Quench & Temper *

These are all "Heat Treat " processes with different results for different applications.

Airframe tube *AISI 4130 * EF 4130 * 4130 Alloy steel - whatever you want to call it ..is the bottom end
of the Aircraft alloys.

4100 designates a Chrome-Moly basic alloy structure
4130 designates a Cr-Mo with 30 points of Carbon (actually .27-.32 point range)

No alloy with less than 40 points of carbon (4140) is considered to be a "Thru-Hardening" grade..

30 points is in limbo....the middle ground

Less than 30 points requires Carborizing (having the surface impregnated with additional carbon by imersion while heating and case-hardening) to improve the Surface hardness..but you only get a hard surface and no depth....

Welding weakens the joint..the intergranular structure changes from the heat and impurities in the flux!

My Raliegh 531 frame like my old Gitane's are "LUGGED"..
All the best are lugged..may not be as pretty..but are the best..and the strongest.

If you Normalize after welding (which is recomended)..it is to make it all uniform strength (Normal)
But if you Normalize & Temper..or Quench & Temper (that is drawing down quickly after heating by imersion into an Oil or Salt Water bath)...How do you plan on straightening the frame after..

It could come out looking like a pretzel..

FitRider 921

It's good to know all of this, but this thread is a bit old...

alspec

Then at least 1 person will have the correct info for the future..and that's you

Brian

Raleigh.

thermo

Nah it's not that old. Only over a year.

FitRider 921

Google works wonders.

KinetikBiker

I like bicycles!

Mines welded!

thermo

Oh yeah?!? MY bike has a chain!

FuzzyRyder

Oh my god... that is pathetic my post got deleted. Grow up we aren't 10 years old.

dooley

blimey, this is old. by the by - sunday heat treat their entire frames post welding.