Self-Weldability of Various Materials in High Temperature Sodium

Abstract

The self-welding behavior of various materials was evaluated by measuring the tensile breakaway force of the specimen which had been self-welded in high temperature sodium. Experiments were carried out to investigate the influence of the sodium temperature and the contact stress on the self-welding behavior.
The results obtained are as follows:
(1) The self-welding behavior in sodium was recognized to initiate by the diffusion of the principal element through the real contact area.
(2) Remarkable self-welding behavior was observed for SUS 316 material at 650°C, and for 2(1/4)Cr-1Mo steel at a sodium temperature of 600°C. The self-welding force acting on the real contact area corresponds to the tensile strength of each material.
(3) Hard chrome plating or hardfacing material showed good self-weld resistance, but the different combinations of SUS 316 with either of these materials were observed to easily cause self-welding.
(4) The self-weldability of Cr₃C₂/Ni-Cr material varied with the preparing methods, especially, with the distribution of the binder composition contained in this material.
(5) A derived equation was proposed to evaluate the self-welding force. It was found that the measured breakaway force was relatively equal to the self-welding force derived from this equation.