Abstract
Investigations for the improvement of impact characteristics of Electroslag (ESW) weld metal was conducted using different types of welding wire. The test was carried out by using six types of welding wire and three levels of welding heat input such as Q=45.6, 79.0 and 126.7 kJ/mm.
The test results obtained are summarised shown as the following.
(1) In the case of all three heat input levels, the vE (absorbed energy) value in core (C) location of ESW weld metal was generally lower than those in rim (R) locations.
Furthermore, regardless of the types of welding wires, the same tendency was noticed.
(2) vE value was improved at C part of the weld metal produced by the wire containing Ni (wire F containig 4.18% Ni) and standard welding heat input of Q=45.6 kJ/mm.
(3) In the previous paper it was comfirmed that the difference of vE values between C and R parts was significantly caused by the difference of ferrite structure types between them. In the C location the formation of extremely dense and massive polygonal ferrite (PF) was certified, and in the R location the formation of fine acicular ferrite (AF) was noticed inside the large austenite (γ) grains.
However, cooling rate of weld metal of C and R locations for -τ1073(800)to773k(500c) in Q=45.6 kJ/mm was not so much to cause the change of structure.
(4) The chemical analytical results of C, Mo and Ni in welding wire, base metal and weld metals showed that the dilution from the base metal into weld metal was comparatively stable (about 50-60%).
(5) Improvement of the vE values at C part were expected thanks to formation of the coarse former austenite (γ) grains by the addition of Ni element.
