Analysis and Process Optimization on Hydrogen Content by Electroslag Remelting of Steel 316H for Nuclear Power

Abstract

In order to find out hydrogen content change law in ESR ingot during electroslag remelting， and on the basis of each process optimize to improve the electric slag ingot hydrogen content qualified rate ， nuclear power steel 316H is taken as the research object to study processing parameters such as melting speed， filling ratio， slag ingredients， amount of slag added， initial hydrogen of electrode and partial pressure of water vapor by using a 15 ton electroslag furnace in this paper.The results show that hydrogen addition is different in each stage of electroslag remelting，the hydrogen content in ESR ingot is proportional to the square root of water pressure in the air. The CaO can promote hydrogen increase and MgO can prevent hydrogen increase in the slag ingredients. Increasing the melting rate， reducing the amount of slag， increasing the filling ratio and improving the cleanliness of the electrode surface are beneficial to prevent hydrogen of electroslag ingot increase. When the initial hydrogen of the electrode is less than 2×10-6， the hydrogen absorption of the remelting process of the electroslag is more serious. When the initial hydrogen of the electrode is in the range of 2×10-6-4×10-6， the hydrogen absorption of the electroslag remelting process becomes weaker. When the initial hydrogen of the electrode is greater than 4×10-6， the electroslag remelting process will appear dehydrogenation.After the process optimization， the average qualified rate of hydrogen reaches 97.5%， which is 2.8% higher than 94.7% before the optimization.

Keywords

• electroslag remelting； hydrogen content； 316h steel； hydrogenation； process optimization