1979 Volume 48 Issue 7 Pages 542-550
The mechanical properties of low silicon 80kg/mm2 high tensile strength steel were investigated. The effect of lowering silicon content on the properties of welds was confirmed using low silicon 80kg/mm2 high tensile strength steel plate manufactured by the practical converter and the mill. The results obtained are summarized as follows.
(1) Lowering silicon content below 0.1wt%, the toughness of weld bond and the lamellartearing susceptibility are improved.
(2) As the result of the improvement of weld bond Charpy impact toughness and fracture characteristics of welds, the allowable weld heat input can be expanded. High Charpy impact toughness of weld bond can be obtained without nickel addition in high heat input welding same as nickel addition steel.
(3) The improvement of weld bond toughness by lowering silicon content is due to the improvement of microstructure, especially the elimination of high carbon martensite island formation in high heat input welding.
(4) The improvement of lamellartearing susceptibility is due to the decreace of the total length of nonmetallic inclusions by lowering silicon content.