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In exploitation, the forging dies are exposed to heating up to very high temperatures, variable loads: compressive, impact and shear. In this paper, the reparatory hard facing of the damaged forging dies is considered. The objective was to establish the optimal reparatory technology based on cooling time t8/5. The verification of the adopted technology was done by investigation of the hard faced layers microstructure and measurements of hardness within the welded layers’ characteristic zones. Cooling time was determined theoretically, numerically and experimentally.

This paper presents the analysis of the influence of temperature on mechanic properties of the base material and welded joints made of high strength steel. The joints were welded on S690QL high strength steel plates using the Metal Active Gas (MAG) Welding and two filler materials of different properties. Since the steel S690QL belongs to a group of steels with high strength, the aim of this paper is to determine the temperature at which strength starts to decrease. Experimental tensile testings of the welded joints were performed at five different temperatures in the range from 20 to 550 °C.

This paper points out complex working conditions of forging dies, which are the most frequent causes of their damage, and proposes suitable hard-facing repair procedures. The shear strength between the hard-faced layer and base metal has been measured using specially developed tool, and correlation between output results and the applied hard-facing technology is established.