The FN Process-A New Submerged-Arc Welding Process to Improve Toughness of Weld Metal (Report 1)
1964 Volume 33 Issue 1 Pages 38-54
Details
1964 Volume 33 Issue 1 Pages 38-54
Explanations are given on the features as well as on the apparatus of the FN process, a new submerged-arc welding process, which authors have developed.
Discussions from the merallurgical view-point are are also given on some experimental data that support the unique features of this process.
Results are given of the welded joint test in which this process was applied for a mild steel and a 60kg/mm2-level high tensile strength steel (quenched and tempered steel).
Test results are summarized as follows :
1. The apparatus of this process can be easily adapted to the conventional submerged-arc welding machine, and the welding procedures of this prccess are as easy as those of conventional proccess.
2. The toughness of welded metal deposited by this process showed a superior value to any other conventional process using fused flux in the market.
3. The cracking resistance of welded metal is very strong. No hot cracking has been observed, which we often experienced in the middle of pear-shaped bead section in the conventional process. This means the welding conditions applicable from the view-point of cracking resistance become broad. It has also been experienced that crater cracks have become remarkably few.
4. The width of softened part in the heat affected zone becomes less than half of that of the coventional process. The fracture at the softened part has not been observed at all in the welded joint tensile test, which has been one of the problems in the welded joint test of the quenched and tempered steel by the conventional processes.
5. It has been found that the width of brittle part in the heat affected zone is smaller and the degree of brittleness is less than that of the conventional processes in the quenched and tempered steel.
6. The rate of deposition in this process can be increased by 30 to 40% in comparison with that of the conventional process, and thus we can save the number of welding layers.
7. One feature of this process is that the width of bead and the height of reinforcement are larger than those of the conventional process although the depth of penetration is smaller.
8. It has also been found that the welding strain in this process is smaller than that of the conventional process.
It may be concluded that this process is more economical than the conventional ones.
