To save the weight of structure, it is general tendency to adopt the low high-tensile-strength steel to the large structures instead of heavy section of mild steel plates.
But it is quite difficult to weld such low alloy steels without causing cracks, because of their hardenability as compared to mild steels.
The authors have studied the weldability of these steels and prepared this report to summarize our present knowledge of the effect of electrode types and preheat temperatures on weldment.
As a result, conclusions have been obtained as follows :
(1) In Kommerell bead bend test, comparison of transition temperature at 45°bending angle to maximum load (ductility transition temperature) or of bending angle to maximum load at temperature -20°C shows the difference between ductile and brittle behaviour of weldments for high tensile steels, while comparison of transition temperature at 90°maximum bending angle (fracture transition temperature) or of maximum banding angle at tmperature 20°C shows little significant effect of electrode type. (See Fig. 9)
(2) Measuring above-mentioned ductility transition temperature, the weldments of low hydrogen type electrods shows sufficient ductility as compared to these of ilmenite or cellulose type electrods, (See Fig. 9)
(3) Little difference has been obtained between the toughnesses of both weldments with ilmenite type electrodes when preheated at temperature 50°C, and with low hydrogen type electrodes without preheating. (See Fig. 14)
(4) In any cases preheating over 250°C is needless. (See Fig. 13)
(5) In general, higher hardness levels in heat affected zone of specimen exhibit lower bending angle to maximum load at temperature -20°C. In this case, hardness over 350 V.H.N. is unfavourable from the standpoint of behaviour of ductility transition in Kommerell test. (See Fig. 17)
View full abstract