Suitability of maraging steel weld cladding for repair of die-casting tooling - Part I: Influence of welding and aging heat treatment on 18% Ni maraging steel weld microstructure and mechanical properties

摘要

A comprehensive study of 18 % Ni maraging steel welds is done in order to determine the suitability of repair welding of aluminum die-casting dies and to prolong the in-service tool life. This study emphasizes the influence of welding parameters and post-welding precipitation annealing heat treatment on the welds' mechanical and metallurgical properties. A series of U-grooved specimens of 1.2344 tool steel is prepared. These grooves are filled with 1.6356 maraging steel as filler wire using multi-pass Gas Tungsten Arc welding. The metallurgical properties of the filler welds, in the as-welded condition and after precipitation annealing with a series of different parameters, are studied. The influence of preheat temperature, heat input during welding, and hot working of maraging steel welds is evaluated regarding mechanical and metallurgical properties. The response surface models for the prediction of mechanical properties (i. e. hardness, toughness, tensile strength, and yield stress after post-welding heat treatment) are developed. The results show that metallurgical and mechanical properties significantly depend on welding technology and post-welding heat treatment parameters. Gas Tungsten Arc welding with low heat input permits the omission of solution heat treatment after welding, while hot working of welds during welding increases the mechanical properties. Developed models for the prediction of mechanical properties enable selection of precipitation annealing parameters for a particular application based on desired mechanical properties.