Analysis of the Effect of Heat Treatment Conditions on the Microstructure and Hardness of Multicomponent Brasses

The effect of various cooling conditions during quenching on the microstructure and hardness of multicomponent brasses has been studied using the example of brass LMtsAZhKS (CuZn13Mn8Al5Si2Fe1Pb). It has been shown that the use of polymer solutions of different concentrations instead of water makes it possible to increase the hardness and change the structural state of the alloys without significant quenching deformations. The cooling rate in MZM-26 oil and 10% solution is close to critical, which suppresses the decomposition of the β‑phase and fixes its unstable state. During subsequent aging, a significant increase in hardness (up to 120% of the initial) occurs due to the formation of a mixed microstructure with martensite and dispersed phases providing effective hardening. The most effective hardening occurs within one hour of aging. The formation of the microstructure during quenching in polymer media is ensured by the redistribution of diffusion-active elements: aluminum and silicon. Maximal hardness is achieved when the processes of nucleation and growth of the α-phase are suppressed, while during aging, shear and dispersion hardening mechanisms are realized.