EFFECT OF AGING TREATMENT ON THE MICROSTRUCTURES AND HARDNESS OF Fe-Ni-Cr SUPERALLOY

Aging treatment was conducted on Fe-Ni-Cr superalloy to observe its effect on the microstructures and hardness of the material. Solution treatments were carried out at 900oC, 975oC, 1050oC, and 1125oC followed by water quenching. The samples were further treated with a double aging treatment at 720oC and 650oC for 4 hours and 12 hours respectively. Materials characterization techniques such as SEM, XRD, and optical microscopy were used to analyze the heat-treated samples. The Fe-Ni-Cr superalloy formed mainly a dendritic austenitic structure with Cr23C6 precipitated along the grain boundaries. Increase in solution treatment temperature results in dissolution of chromium carbide, coarser grain, and lower hardness for non-aged samples. Double aging treatment produced more chromium carbide, higher hardness, but no apparent change in grain size. Neither quenching nor aging treatments caused any phase transformation. The highest hardness value of 220.4 Hv was recorded for the sample solution treated at 1125oC for 2 hours and water quenched, followed by 2-step aging at temperature 720oC and 650oC for 4 hours and 12 hours respectively, and air cooled

Effect Of Cooling Rate On Microstructures And Mechanical Properties Of C102 Copper Alloy

The objective of this study is to illustrate the effect of two types of heat treatment on microstructure and mechanical properties of C102 copper alloy. Annealing and quenching were conducted to study the effect of cooling rate on material. Specimens were heated at 350, 400 and 500oC and were cooled by using two types of cooling medium; furnace cooling and water quench. Tensile strength of 254.6 MPa was obtained for the asreceived specimen. It was shown that an increase in cooling rate contributed to a higher strength due to local strain effect. Rapid cooling in quenched specimen had successfully increase the hardness by 41% and recorded the highest tensile strength of 359 MPa while slow cooling rate which experienced by an annealed specimen resulted in the lowest tensile strength of 136 MPa. Microstructure investigation shows annealed specimen produced coarse austenitic structure with larger grain size. Meanwhile, quenched specimen produced finer austenitic structure with smaller grain size. It was observed that the grain size of annealed specimen was increased with soaking temperature, however, quenched specimen shows the other way around

Effect of Heat Treatment on Microstructure and Mechanical Properties of 6061 Aluminum Alloy

The objective of this study was to illustrate the effect of various cooling rate and precipitation hardening on microstructure and mechanical properties of 6061 aluminum alloy. Samples were solution treated at 400oC before cooling in furnace, air, and water quench. Precipitation hardening was conducted by solution treating samples at 530oC followed by water quench and reheating at 100oC and 200oC. It was observed that the fast cooling rate on quenched sample produced finer grain and higher strength while slow cooling rates on annealed sample produced coarser grain and lower tensile strength. Longer precipitation hardening time resulted in larger precipitates size which led to drop in strength (over aged). Meanwhile, higher temperature resulted in shorter time to reach over aging. Precipitation hardening at 100oC for seven hours had successfully increased the UTS by 95.9% to 625 MPa due to formation of finely dispersed precipitates. Meanwhile, annealing had lowered the UTS by 62% to 197 MPa due to formation of coarser grain