This study emphasizes the influence of welding parameters and post-welding precipitation annealing heat treatment on the welds properties. 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 hardness, toughness, tensile strength, and yield stress after post-welding heat treatment are developed. Metallurgical and mechanical properties significantly depend on welding technology and post-welding heat treatment parameters.
COBISS.SI-ID: 10944795
For repair welding of tools, laser technology has recently been used with major benefits such as localized heating effect, narrow heat effected zone and negligible undercuts. In this paper, the technology of thermal cracks repair (grooving, welding) with pulsed Nd:YAG laser is described. A microhardness analysis of areas surrounding cracks, grooves and welds has been performed, also. The test results suggest that it is relatively fast and easy to eliminate the fatigue area surrounding the cracks, and with proper welding to reestablish the tool operability.
COBISS.SI-ID: 10714651
The thermal fatigue resistance of different hot-work tool steels was studied; AISI H11 and H13, special tool steel and 18% Ni maraging steel. An innovative apparatus for thermal fatigue testing is developed to study the thermal fatigue resistance. The microstructure, hardness profile and the surface cracks developed are analyzed. The specimens of special geometry and optimal set of testing parameters are developed using finite element modeling to improve testing efficiency. The best thermal fatigue resistance achieved special tool steel due to its high thermal stability.
COBISS.SI-ID: 10290971
This paper presents the investigation of influence of different pulse shapes on laser repair welding/cladding of cold-work tool steels with the pulsed Nd:YAG laser. Repair welding tests were carried out on AISI D2 tool steel, quenched and tempered to hardness of 56 HRc, followed by microstructural analysis and investigation of defects with scanning electron microscopy. Test results suggest that it is possible to obtain sound welds without preheating, with the right selection of welding parameters and appropriate pulse shape.
COBISS.SI-ID: 11222555
The influence of post-weld precipitation annealing heat treatment and aluminium die casting thermal cycling on metallurgical and mechanical properties was analysed. Test specimens were analysed after thermal fatigue cycling. The weld microstructure and hardness were evaluated. A model for prediction of precipitation annealing time during aluminium alloy die casting was proposed. The results showed that tool heating lasts 30% of molten metal injection time, preparing conditions for precipitation annealing at 10% of injection time, and precipitation annealing at 60% of injection time.
COBISS.SI-ID: 10658843