Effect Of Heat Treatment Duration Research Articles

Effect of Heat Treatment Duration and Cooling Conditions on Flexural Strength and Surface Roughness of Cobalt-Chromium Alloys produced by Selective-Laser-Melting

Post-heat treatment may enhance mechanical properties of selective laser melting (SLM) Cobalt chromium (Co-Cr) alloys, however it is unknown what duration the heat treatment needs to last and how the rate of cooling impacts the alloy's flexural strength and surface roughness. In this study, SLM Co-Cr alloy specimens were heated at 1150 C for 1 or 6 hours and subsequently cooled by air cooling (AC), furnace cooling (FC), or water quenching (WC). Flexural strength and surface roughness were then tested. Aim of this study: Investigate the effect of heat treatment and different cooling conditions on the flexural strength and surface roughness of SLM Co-Cr alloy specimens. The heat treatment will be conducted at 1150 C for two different durations (1-hour and 6-hours) and under three cooling conditions (AC, FC, and WC). Materials and methods: A total of forty-two rectangular specimens, measuring (34×13×1.5 mm) were manufactured through SLM and divided into seven groups, six specimens for each group as follows: The first group denoted as control with no heat treatment and no cooling applied, second and third groups heated for 1 or 6 hours then cooled in the air (AH-1 and AH-6), fourth and fifth groups heated for 1 or 6 hours and left inside the furnace until they cooled (FH-1 and FH-6), sixth and seventh groups heated for 1 or 6 hours and cooled by water quenching (WH-1 and WH-6). Flexural strength and surface roughness tests were performed on the specimens. A flexural strength value of (2147.33 MPa) was indicated that the control group exhibited the highest flexural strength, whereas the FH-6 group exhibited the lowest flexural strength value (1282.66 MPa). The control group showed the worst surface roughness (1.63 μm) while all other groups demonstrated no significant differences in surface roughness ranging from (0.32 to 0.49 μm) with a slight increase in the 6-hours heated groups. Conclusions: Slow cooling rate inside the furnace affects flexural strength negatively. Therefore, a high cooling rate is recommended to get a better flexural strength. On the other hand, surface roughness results suggests that 1-hour is better than 6-hours in terms of heat treatment duration and time saving

Effect of Heat-Treatment Duration on Antioxidant Activities of Muscle, Liver and Other Parts of Grass Turtle (Chinemys reevesii)

Effect of Heat-Treatment Duration on Antioxidant Activities of Muscle, Liver and Other Parts of Grass Turtle (Chinemys reevesii)

Effect of Heat Treatment Duration on Interface Characteristics of Explosively Bonded Cu/SS-304 Plates

The effect of heat treatment on the microstructure and metallurgical properties of the interface between copper and austenitic stainless steel 304 formed by explosive bonding using different conditions of stand-off distance and material thickness was studied. Laboratory studies were carried out using optical microscopy, scanning electronic microscopy, and microhardness measurements to evaluate welded samples. Samples were subjected to heat treatment in a furnace at 300 °C for 22 or 30 h, then cooled in air. Microstructural studies showed that, as the stand-off distance and explosive load were increased, the interface between copper and stainless steel 304 became more wavy. The microhardness results showed that the hardness of the base metal was greater than in other areas near the interface because of extreme plastic deformation due to the explosive force. The results also showed that, as the temperature and heat treatment duration were increased, the hardness of the flyer plate at the interface decreased compared with before heat treatment.

Research in the Field of Composite Materials Based on HCBS and Refractory Materials Based on the System Al2O3–SiO2–SiC. Part 41

The effect of heat treatment duration of the properties of specimens prepared on the basis of composite composition HCBS in the Al2O3–SiO2–SiC system is studied. With a content of 10 and 30% SiC in specimens its fineness varies within the limits 3 – 200 μm. Amethod is proposed for evaluating the degree of SiC oxidation within composite material. Depending on specimen composition this index is within the limit 50 – 100%. Maximum values of σben and σco for SiC-containing specimens reach 80 and 390 MPa respectively.

Effect of heat treatment duration on the thermal conductivity of spruce and poplar wood

Changes in the thermal conductivity and density of Pannonia poplar (Populus x euramericana cv. Pannonia) and spruce (Picea abies) caused by heat treatment were examined. The specimens were treated at 180 °C for 15, 25 and 35 h. Treatment duration had different impact on both the density and the thermal conductivity of poplar and spruce. The density of poplar decreased by 9.1, 12.1 and 13.4%, and the thermal conductivity decreased by 16.9, 24.0, 29.1% after 15, 25 and 35 h of treatment, respectively. In the case of spruce, the density decreased by 5.2, 7.6 and 8.7%, and the heat conductivity by 7.4, 14.1 and 22.0%, respectively.

Effect of heat treatment duration on tribological behavior of electroless Ni-(high)P coatings

Electroless nickel coating occurs through an autocatalytic chemical reaction and without the aid of electricity. From tribological perspective, it is recommended due to its high hardness, wear resistance, lubricity and corrosion resistance properties. In this paper electroless Ni-P coatings with high phosphorous weight percentages are developed on mild steel (AISI 1040) substrates. The coatings are subjected to heat treatment at 300°C and 500°C for time durations up to 4 hours. The effect of heat treatment duration on the hardness as well as tribological properties is discussed in detail. Hardness is measured in a micro hardness tester while the tribological tests are carried out on a pin-on-disc tribotester. Wear is reported in the form of wear rates of the sample subjected to the test. As expected, heat treatment of electroless Ni-P coating results in enhancement in its hardness which in turn increases its wear resistance. The present study also finds that duration of heat treatment has quite an effect on the properties of the coating. Increase in heat treatment time in general results in increase in the hardness of the coating. Coefficient of friction is also found to be lesser for the samples heat treated for longer durations (4 hour). However, in case of wear, similar trend is not observed. Instead samples heat treated for 2 to 3 hour display better wear resistance compared to the same heat treated for 4 hour duration. The microstructure of the coating is also carried out to ensure about its proper development. From scanning electron microscopy (SEM), the coating is found to possess the conventional nodular structure while energy dispersive X-ray analysis (EDX) shows that the phosphorous content in the coating to be greater than 9%. This means that the current coating belongs to the high phosphorous category. From X-ray diffraction analysis (XRD), it is found that coating is amorphous in as-deposited condition but transforms into a crystalline structure with heat treatment.

Study of Physical Properties of PbTiO3 Based Glass-ceramic with Variation of Heat Treatment Duration

PbTiO3 glass-ceramics were prepared by following two stage heat treatment schedule. The effect of heat treatment duration on the physical properties of glass-ceramic was studied. The density, CTE, dielectric constant and ferroelectric properties varied systematically with heat treatment duration and exhibited an optimum for 32 h. These properties have a good correlation with the volume fraction of lead titanate phase crystallized in the glass-ceramics. Impedance spectroscopy was used to analyse the behaviour of glass-ceramic samples. The studies of ferroelectric properties show that PbTiO3 glass-ceramics has a potential for high temperature applications.

The effect of heat treatment duration on mechanical and tribological characteristics of Ni–P–PTFE coating on low carbon high tensile steel

The current work aimed to study the effect of heat treatment duration on mechanical and tribological performances of Ni–P–PTFE coating on low carbon high tensile steel (EH-36) substrate in dry environment under pin-on-disk sliding contact. The effect of normal load on scratch behaviors of Ni–P–PTFE coating with different heat treatment durations was studied under a single pass scratch action. It was found that heat treatment enhances the friction (10%) and wear (30%) behavior of Ni–P–PTFE coating. Heat treatment duration was found to have significant role in strengthening the Ni–P–PTFE coating tribological performances under varying load applications. The best tribological performances and scratch behaviors were observed on HT 80.

Effect of heat treatment on the mechanical properties of PIP–SiC/SiC composites fabricated with a consolidation process

Continuous SiC fiber reinforced SiC matrix composites (SiC/SiC) have been considered as candidates for heat resistant and nuclear materials. Three-dimensional (3D) SiC/SiC composites were fabricated by the polymer impregnation and pyrolysis (PIP) method with a consolidation process, mechanical properties of the composites were found to be significantly improved by the consolidation process. The SiC/SiC composites were then heat treated at 1400°C, 1600°C and 1800°C in an inert atmosphere for 1h, respectively. The effect of heat treatment temperature on the mechanical properties of the composites was investigated, the mechanical properties of the SiC/SiC composites were improved after heat treatment at 1400°C, and conversely decreased with increased heat treatment temperature. Furthermore, the effect of heat treatment duration on the properties of the SiC/SiC composites was studied, the composites exhibited excellent thermal stability after heat treatment at 1400°C within 3h.