PHYSICO-CHEMICAL METHODS OF INCREASING THE CRACK RESISTANCE OF ALLOY AM4.KD (VAL10). NOTICE 3: INFLUENCE OF HYDROGEN TREATMENT OF THE MHL ON CRACK RESISTANCE
Procesi littâ, 2023, Vol 4 (154), 3-14
DOI:
https://doi.org/10.15407/plit2023.04.003Keywords:
crack resistance, hydrogen treatment of the melt, AM4.5Kd alloy (VAL10)Abstract
The article examines the effect of hydrogen treatment (HW) of AM4.5Kd melt (VAL10) on the tendency of a casting solidified under conditions of inhibition of linear shrinkage, localization of deformations and difficult feeding, to the formation of hot cracks, and a refined mechanism of the positive effect of HW on crack resistance is proposed. In the work, a specially developed test for crack resistance was used, control castings were hardened with the formation of a crack. The complete absence of a crack was considered a positive result of the VO. The heating of the melt was carried out by gassing it with water vapor by submerging a tampon made of wet mineral wool below the level of the melt. The indicators of strength and density of the obtained castings were studied. It was found that under the conditions of the experiment, the efficiency of the BM was 60%, and the strength of the metal of the samples obtained after the BM of the melt exceeded the metal strength of the control samples, as a result of the replacement of the sharp-angled pores formed under conditions of difficult feeding with rounded gas pores. The analysis of the results makes it possible to conclude that the positive effect of hydrogen treatment is achieved due to the prevention of the pressure in the casting from going to negative values with subsequent rupture of the melt and the formation of a crack, reducing the degree of localization of deformations (which is the main reason for the formation of a crack) and curing the crack with a melt that squeezes hydrogen bubbles out of it.
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