PSI - Issue 65

A.V. Sulitsin et al. / Procedia Structural Integrity 65 (2024) 282–289 A.V. Sulitsin, , S.V. Brusnitsyn, D.O. Levin, D.A. Usov, V.K. Dubrovin / Structural Integrity Procedia 00 (2024) 000–000 3

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brass must contain an α-phase (no more than 60 vol. %), uniformly distributed intermetallics (12...18 vol. %) and a secondary mixture of (α+β')-phases (the rest). In this case the following values of mechanical properties in the deformed state must be ensured, not less than: σ b =550 MPa, δ=8%, НВ=180. A structure with the required ratio and sizes of phase components can be obtained by modifying these alloys. As a rule, modifiers for copper alloys are V, Ti, W, Mo, B. The purpose of this work was to study the influence of modifiers on the structure and properties of complex-alloyed brass 70Cu-13Zn-7Mn-5Al-2Fe-2Si-1Pb. Mischmetal, niobium, magnesium-cerium, iron-boron and iron-titanium ligatures were used as modifiers. The experiments were carried out in laboratory conditions. The amount of the added modifier varied from 0.01 to 0.3 wt. %. A control ingot was cast for comparison. The ingots were cast in a steel chill mold with an internal diameter of 50 mm and a height of 300 mm. The alloy pouring temperature was 1150 ºС. For metallographic examination and hardness measurement, the ingots were cut along the longitudinal axis. The average grain size was determined in the center, at half the radius and in the surface zone of the ingot according to Saltykov method (see Saltykov (1976)). It has been established that the average grain size in the control ingot is 1.221 mm, with the introduction of modifiers iron-boron, iron-titanium, niobium, mischmetal, magnesium-cerium 1.010, 1.005, 0.709, 0.668, 0.608 mm, respectively. The results of the metallographic study indicate that the greatest effect on grain refinement was obtained when using the magnesium-cerium ligature. In the analysis of the microstructure, the main attention was paid to the size and distribution of intermetallic particles and the volume fraction of the α-phase. The results of the metallographic study of alloy structure are given in Table 1. 2. Experiments, results and discussion

Table 1. Results of metallographic study of microstructure of alloy 70Cu-13Zn-7Mn-5Al-2Fe-2Si-1Pb.

Modifier

Modifier quantity ( wt. % )

Average size of intermetallics with needle-like morphology ( μm )

Distribution pattern of intermetallic compounds

Volume fraction of

α-phase ( vol. % )

Control ingot

0

200

Uneven, with clusters of intermetallics of rosette morphology Uneven, with clusters of intermetallics of rosette morphology Uneven, with clusters of intermetallics of rosette morphology Uneven, with clusters of intermetallics of rosette morphology

70

0.05

150

60

0.1

100

60

Mischmetal

0.2

80

55

0.3

40 80 75

Even

55 55 55 50 50 60 55 60 55

0.05

Uneven

0.1

Uneven, intermetallics of rectangular and rosette morphology are present

Magnesium-cerium

0.2 0.3

60 40

Even Even

0.05

160

Uneven, with twin intermetallic needles and clusters of finely dispersed intermetallic compounds

0.1 0.2 0.3

100

Uneven

Niobium

60 60

Uneven, with clusters of finely dispersed intermetallics

Relatively even