There is another welding process called Thermite welding. It is also known as exothermic welding
It is used in the railway industry to weld long sections of rail.
Basically you lay the two rails butting them up against each other.
You then build an empty "volcano with heat resistant putty.
You then fill this "volcano" with Iron oxide and aluminium powder.
You then ignite the powder mix.
The aluminium and iron oxide react very violently to then become Aluminium oxide and iron. The huge amount of heat also melts the two rail ends together.
Another powder combination can be used, copper oxide and aluminium. for the formation of electrical joints.
When the reaction is proceeding, it does look like a volcano.....
After its all cooled down, apply angle grinder till you have a continuous rail with no perceptible joint... and hence no clackety clack of train carriage wheels over the rail joint.....