Abstract
The strengh of electron beam welded joint in six maraging steels has been measured and discussed on the basis of microstructural features and the strength of weld metal.
The strength of the welded joint of steels except No. 6 steel increases proportionally with the increase in the strength level of the base metal. In No. 6 steel the strength of the welded joint is remarkably lower comparing with the strength of the base metal. The joint efficiency is usually about 90%, but that of No. 6 steel is 75%.
The lower joint efficiency in No. 6 steel can be explained by the fact that the weld metal have the low strength as the result of the formation of the large amount of the stable austenite. The amount and the stability of the austenite phase increase remarkably, when Ms temperature in the base metal is lower than 200°C.
The maximum strength of base metal for which the strengthening is effective, is more than 300 kgf/mm2 if it is evaluated from smooth tensile test of welded joint. The maximum strength is 270 kgf/mm2 when welded joint is evaluated from notch tensile test of weld metal.
