Abstract: In order to investigate the wear regularity of hot-extrusion die for large-diameter thick-walled pipe, ASME SA-335P91 steel and AISI H13 steel are taken as research objects. Combined with actual tests and finite element simulation, the influence of temperature and holding time on die wear is analyzed. Obtained from the working conditions of the mold:in the initial contact of the metal billet with the die, the temperature rise of the die surface has a great influence on the wear; when the metal billet and the die are in thermal equilibrium, the duration of the state and the current temperature are the main factors affecting the wear. The temperature-hardness equation and the temperature-wear coefficient equations are obtained at the initial contact of the metal billet with the die. The time-hardness equations and the temperature-wear coefficient equation are obtained under thermal equilibrium. Combined with the Archard wear theory, the wear regularity of hot extrusion die for large diameter thick wall pipe is obtained. Finally, the secondary development of the finite element software shows that the predicted value is basically consistent with the high temperature wear test value, which can provide theoretical support for the optimization design of the die wear.

Key words: die-softening test, high temperature hardness test, high temperature wear test, hot extrusion die, large diameter thick-walled pipe, wear regularity