The effect of heat treatment on the microstructures and mechanical properties of copper alloy

Mohamad Syafiq , Mokhtar (2013) The effect of heat treatment on the microstructures and mechanical properties of copper alloy. Project Report. UTeM, Melaka. (Submitted)

PDF (24 Pages) cdr_10201-24_pages.pdf - Submitted Version Download (296kB)

Abstract

Copper is an essential element for major industrial metal because of its high ductility, malleability, thermal and electrical conductivity and resistance to corrosion. Copper and its alloy mainly used in wiring production, piping, automotive and architecture. Heat treatment process was applied on copper and copper alloys in order to attain the desired properties for each application. The effect of heat treatment on the microstructures and mechanical properties of copper alloy has been studied with different heat treatment processes which are annealing, water quenched and aging. Tensile test and metallurgical investigation is carried out to achieve the objective. In term of cooling rate, the effect of annealing process and quenching process has been investigated at different temperature. Aging process is studied with different temperature and aging duration. Yield strength and ultimate tensile strength of annealed specimens were decreased on 350oC to 450oC from 204.73MPa to 129.15MPa and 207.66MPa and 135.83MPa respectively. The softening of the specimens was due to the reduction of dislocation density in the structure and the grain growth that leads to the coarsening of the grain. Greater yield strength and ultimate tensile strength has been observed on water quenched specimens at 450oC which record 356.34MPa and 358.89MPa. The hardening of material was due to the finer grain structure obtained by the decreasing of grain size after water quenched. For aging process, peak strength has been obtained by specimen aged for 4 hours at 450oC which recorded 542.38MPa of yield strength and 559.69MPa of ultimate tensile strength. Peak strength was achieved with an increased strain field on the structure produced by coherent precipitates. The finer grain structure is observed on this stage that leads to strain hardening. Lowest strength was recorded on specimen aged for 8 hours at 450oC which recorded 441.66MPa for yield strength and 452.24MPa for ultimate tensile strength. The reduction of strength is caused by overaging. Overaging was occurred by the coarsening grain structure and loss of precipitate coherency. Hence, the mechanical properties and the microstructures are altered accordingly.

Actions (login required)

View Item