Fillet Welding Rail 4

[dik]

Is it possible to fillet weld the base of a rail to a steel bearing/attachment plate? I know they have weldable Pandrol rhoulders, but can the rail be welded directly?

Dik

 

[hokie66]

Dik, I am not a railway engineer, but I would say no. You want the rail to be able to move, and I think welds would break in no time.

 

[metengr]

I would agree with the above post. Do not fillet weld the rail because the rail moves moves from thermal/mechanical stresses.

 

[dik]

Thanks, the rail base will be bearing on concrete, several feet thick and will not move. Do they use vibration isolators with rail? I'm not a rail specialist either, but am thinking of problems.

I know from an earlier post that rail on normal ballast moves, but is it essential that it be able to move?

The loading on fillet welds can be kept to a pretty low stress level and I was more concerned about the metallurgy of the rail for welding. I know that for continuous rail the thermite process is used with a high preheat.

Dik

 

[hokie66]

Even with a continuous rail, it still needs to be able to move longitudinally. Not much, but that's what the spring clips are for.

 

[MikeHalloran]

>>>the rail base will be bearing on concrete, several feet thick and will not move.<<<

When the temperature changes, one of them will move.


Mike Halloran
Pembroke Pines, FL, USA

 

[tstanley]

Whether it moves or not, it is not good to weld on rail because of the existing heat treatment of the rail. Even sparks from welding near a rail are enough to change the properties in a small area which can cause the rail to break. The heat affected zone becomes very brittle.

 

[dik]

Thanks, Mike... the condition is that the rail can move a short distance from the concrete base and that it would only be secured for a distance of about 10'. I didn't think the thermal movement over 10' would be significant enough (even for northern Canada).

tstanley:
Thanks, I don't know about the metallurgy of rails or the manner of production or fabrication. I was concerned about it causing the rail to crack, but didn't realise it was as sensitive as you've noted. I knew for continuous welded rails that the thermitic process relies on a fairly high pre-heat. I didn't realise that rails were heat treated... makes sense... induction? Do they have to be treated after thermitic welding? Thanks again.

Dik

 

[tstanley]

I think the heat treatment varies depending on customer requirements, and varies throughout the profile. If it's head hardened it usually says so on the web of the rail. With some rail these days the head can be hardened up to 410 Brinell whereas the web and base can be 250 brinell.

I don't know if the joint is heat treated after thermite welding, but the more modern flash butt welding is computer controlled to minimize the heat affected zone.

We have a few rail carts to move stuff around the shop and every time we weld on the rail for them, for one reason or another the rail breaks at the weld.

 

[dik]

Thanks tstanley:

I will be using Pandrol weldable shoulders secured to the plate and use Pandrol clips to secure the rail. My original idea of welding the rail seems fraught with problems.

thanks, Dik

 

[dik]

Have picked up a lot of information about rail. It is a far more specialised product than I had initially known. I've also learned that it is safer to err by not welding it at all.

I've heard that the head can be hardened to 880 Brinell...

I've secured it to my steel plate channel 'bridge' by means of weldable Pandrol shoulders.

Thanks to all,

Dik

 

[kingnero]

Not welding the rails is generally a good idea.
If you weld, don't weld at the foot of the rail, where it is loaded in tension.
If you weld (MMA = SMAW), preheat to at least 300° Celsius.
and use basic coated (low hydrogen) electrodes.

880 Brinell seems exceptionally high, in Belgium the standard value is 200 Brinell (not heat treated), and only for small radii the head of the rail is heat treated to 360 Brinell.

 

[dik]

kingnero...

I didn't know that they 'selectively' hardened portions of the head...

Welding is fraught with too many problems and I've avoided this, completely... I had never considered that rail coud be affected by a single spark. The steel 'channel bridge' and weldable shoulders will be shop fabricated and cast into concrete and the rail is held by spring clips only...

Again, thanks for all the assistance...

Dik