Genesis of a Victoire frame : step 2
The framework of the moutain bike that will be exposed on the Formula booth is going well, and today we want to share with you the most important step: the welding.
At Victoire, we use a welding process called fillet-brazing, which we believe has the most suited features for the realization of a customized frame. This welding method is described as heterogeneous since the filler metal is not the same as the tubes metal. It offers many advantages:
- The filler metal has a much lower melting temperature than the steel tubing that we use. Therefore, it cancels the phenomenon of heat-affected zone (or HAZ). Indeed, if the tubes are heated too intensely, the area near the welding will be deteriorated and might have lower mechanical properties. With TIG welding (a welding process chosen for the majority of steel or aluminum frames), there is almost always a HAZ, which leads to a weakening of the frame just after welding. Our solder melting at about 800 °, our tubes are not affected and the frame is a lot more stronger.
- We use specific rods for our frames. After numerous tests, we selected a brazing filler metal developed in France. This alloy is a composition of several metals in order to obtain excellent weldability and high mechanical characteristics.
- We polish our fillets to obtain a perfectly smooth rendering. The goal is obviously aesthetics but also mechanics. Indeed, polishing welds eliminates the stress concentration phenomenon. In the case of an unpolished welding, every edges and rough edges will stop stress and can lead to the creation of micro-cracks, which then cause the frame breakage.
We hand polish every welding in order to obtain a perfectly smooth rod to touch. Each weld takes approximately 1 hour to be polished. First we work on the front triangle and chainstay. After checking, we add the seatstays and small parts that need to be welded to the frame.
This frame is a bit specific because the rear derailleur cable and brake hose fully pass on the inside of the frame. We have worked for 12 months on this solution, and this framework will have the latest evolution. We will unveil more details of this specific framework on Wednesday, before painting the frame.
Additionnal information : we have just changed our welding system into a new one. We now use the gazflux system. Before that, we needed to apply a paste into the welding zone to allow the brazing, now the paste is directly added to the flamme, making the process much easier and reliable. Erwan our welder couldn't be happier with that!