Age Hardening Treatment Research Articles

Tribological performance and 3-D surface characterisation of age-hardened Al2090-based ceramic composites

This study investigates the synergistic influence of boron nitride (BN) tertiary ceramic additives and age-hardening treatment on the microhardness and wear resistance of Al2090-based hybrid composites, fabricated using the stir casting method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies are carried out to assess the phases present, microstructure, and surface properties, respectively. The metallurgical investigations confirm a relatively superior uniformity in the distribution of particles and the ageing of precipitation at 150°C, vis-à-vis the other temperatures explored in this study. The experimental examinations conducted as per ASTM (E8 and G99) standards revealed a significant improvement in both the hardness and the primary tribological properties, when micron-sized boron carbide, graphite, and boron nitride were used as reinforcements. Age-hardened samples, especially the hybrid composite HS-2 with 5 wt.% each of boron carbide, graphite, and boron nitride, demonstrated an enhanced hardness of 25.23% and lower surface roughness (44.3 nm) compared to Al2090 (AS), due to the presence of load-bearing ceramic reinforcements. Increasing the applied load led to higher wear rates and coefficients of friction for Al2090. However, heat-treated hybrid metal matrix composites (HMMCs) exhibited a contrary behaviour, suggesting enhanced durability. The investigation highlighted the better wear resistance of heat-treated and near-optimally reinforced HMMCs, indicating their potential candidature for wear-resistant aerospace applications.

Effect of thermo-mechanical age hardening on the strength and electrical conductivity of Copper-AA6063 bimetallic wire.

This research explored the impact of age-hardening treatment on the mechanical response and electrical resistivity of copper-clad AA6063 alloy bimetallic wire, with a focus on microstructural analysis and interface characterization. In this study, AA6063 alloy wire was inserted into an oxygen-free high conductivity copper tube, and a bimetallic wire was fabricated through a wire drawing process that reduced the cross-sectional area in 13 stages. The bimetallic wire underwent a series of thermo-mechanical treatments, including various combinations of wire drawing, solution heat treatment, and artificial aging. The findings revealed that applying solution heat treatment prior to wire drawing, followed by artificial aging after drawing, produced a clean interface free of intermetallic compounds. This processing approach resulted in a Cu-Al bimetallic wire with a strength of 286MPa and an electrical conductivity of 80% IACS. Furthermore, the electrical conductivity-to-density ratio reached 13% IACS/(g·cm⁻³), representing a 16% improvement over oxygen-free high conductivity copper.

Effect of precipitation hardening on the microstructure, mechanical, and corrosion properties of additively manufactured A20X aluminum alloy

The effect of age hardening treatment on microstructure, tensile properties, and corrosion behavior of additively manufactured A20X alloy was investigated. Three single-step aging temperatures (150 °C, 175 °C, and 200 °C) and one double-step aging temperature (pre-aging at 165 °C followed by aging at 185 °C) along with varying heat treatment durations ranging from 30 min to 144 h, were studied systematically. Microstructural characterizations revealed that the co-existence of coherent/semi-coherent (Ω, θ′) and incoherent precipitates (θ) resulted in the maximum hardening effect (up to 30 % higher microhardness). This improved the yield strength at room and 150 °C by 33.4 % and 22.6 %, respectively. Double aging delivered the best combination of microstructure with fine grains and optimal precipitate assembly in a short duration (12–16 h). The heat-treated LPBF A20X showed higher ductility and similar mechanical properties compared to the cast A20X. However, optimal precipitate characteristics reduced the corrosion potential by 13–16 % due to a higher galvanic reaction. The highest corrosion potential (−0.622 V) was achieved in the solutionized state.

Fatigue response of AlSi10Mg by laser powder bed fusion: influence of build orientation, heat, and surface treatments

The aim of this study is to analyze how the fatigue behavior of AlSi10Mg by laser powder bed fusion is affected by build orientation, heat, and surface treatments. A three-by-three factorial plan has been arranged for this purpose. Particularly, regarding the heat treatment, three levels were considered (as built, age hardening, and stress relief); whereas, for the surface treatment, three levels were investigated (micro-shot-peening, micro-shot-peening plus fine blasting, and machining and lapping following laser powder bed fusion). Regarding the build orientation, the specimens were manufactured using three different build orientations (0°, 45°, and 90°). The obtained data have been statistically analyzed by a three-factor ANOVA-based method. The results, supported by fractographic and micrographic microscopy analyses, indicate that the age-hardening treatment yields the maximum benefits, whereas stress relief may even have a detrimental effect. As for surface treatments, a positive influence of shot-peening has been found.

Influence of Post-processing and Build Direction on the Wear Behaviour of Laser Powder Bed Fused Maraging Steel

Abstract Present study investigates the effect of post processing (heat treatment: solutionising at 850°C for 2 hr with aging at 490°C for 3 hr and cryogenic treatment at -196°C for 24 hr) and the effect of build direction (along the build direction (BD) and perpendicular to the build direction (PBD)) on the wear behavior of maraging steel fabricated by Laser powder bed fusion (LPBF). The results are also compared with conventional hot-forged samples. The pin on disc equipment was used to conduct the wear experiments with an EN31 steel disk as the counter body. Heat treatment decreased the wear rate of LPBF material by 54.78% and 83.84% in BD and PBD, respectively. This is due to the restriction of grain expansion by the Ni-based precipitants in age hardening treatment. The cryogenic treatment further decreased the wear rate of LPBF material by 87.84% and 90.9% in BD and PBD, respectively. This significant reduction can be attributed to the change of phase to martensite, as confirmed through microstructure and X-ray diffraction (XRD) analysis. Moreover, hot forged material also obtained a reduced wear rate after heat and cryogenic treatments. The highest wear resistance was found with the LPBF cryo-treated BD sample due to increased hardness from 388 HV to 640 HV. The worn surface of test samples was examined by using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), 3D profilometer, and XRD analysis. Oxidation wear, adhesive wear, and abrasive wear are the predominant wear mechanisms identified using SEM.

Influence of heat treatments on low-power-LPBFed CuCrZr for nuclear fusion applications

In this study, the processability of CuCrZr alloy with additive manufacturing (AM) technology and the performance achievable with Direct Age Hardening treatments for nuclear fusion applications were investigated. This copper alloy is one of the most interesting for the field: it is easier to manufacture through Laser-based additive manufacturing technology and mechanically superior compared to pure copper, and it ensures values of thermal conductivity high enough to be considered a valid substitute for pure copper in many applications.The investigation on CuCrZr alloy was carried out in order to examine the influence of Direct Age Hardening (DAH) treatments on physical and mechanical properties. Laser Powder Bed Fusion technology was used to produce samples with CuCrZr alloy. The additive manufacturing process involved a machine provided with a 370 W IR laser and a preliminary process optimization was carried out to find the printing parameters that assured the highest density (99.15 %), which confirmed the processability of CuCrZr alloy also with low IR laser power. Then, three different DAH treatments were tested and the performance of DAHed material was compared to that of the alloy in as-built conditions. Precipitation phenomena were investigated with DSC analyses, revealing the effectiveness of the treatment already after 1 h. A deep microstructural investigation revealed a fine cellular structure formed during solidification and the presence of nanometric precipitates starting from the as-built condition. The presence of microstructural defects was also investigated. Mechanical performance and thermal conductivity were tested, too: the as-built samples showed limited properties, while very promising results for the use of additively manufactured CuCrZr components have been obtained after the DAHs. The ultimate tensile strength (UTS) and yield strength (YS) doubled the as-built values after 1 h treatment at 550 °C. The thermal conductivity reached three times the initial condition (from 100 W/mK to 300 W/mK).

Synergistic effects of cold rolling and age hardening on the hardness and tensile characteristics of AA6061 hybrid composites

The present study involves the fabrication of aluminium alloy 6061 matrix hybrid composites with varying weight fractions of silica sand and copper particles by employing the conventional stir casting method. The combined influence of age hardening (AH) and low temperature thermomechanical treatment (LTMT) on the hardness and tensile properties of AA6061 hybrid composites was investigated. The uniform dispersion of the particles in the matrix was confirmed by microstructure analysis and the improvement of Brinell hardness values. The composites exhibited higher tensile strength and hardness than the base alloy. Both AH and LTMT enhanced the properties of the hybrid composites and a comparison between them revealed the best results for LTMT hybrid composites. The LTMT hybrid composite with 3 wt% silica sand and 3 wt% copper (3S3C) subjected to 12% rolling deformation and aged at 100 °C had the highest hardness and tensile strength of 144.26 HV and 290 MPa respectively. The hardness and tensile strength of AA6061-3S3C hybrid composite subjected to LTMT in peak aged condition showed an improvement of 125 and 97% respectively when compared with those of AA6061 alloy. Fracture surface analysis of the thermomechanical treated composites in peak aged condition showed a mixed mode of failure dominant with the ductile fracture.

Hybrid Treatment and Natural Aging Behavior of Peak-Aged Eutectoid Steel Powder-Reinforced Al 7075 Matrix Composites

The current work focuses on the natural aging phenomenon of a eutectoid steel powder-(0.8 wt.%) reinforced Al-Zn-Mg (Al 7075) alloy, which was subjected to a hybrid heat treatment. The hybrid treatment comprises the aging treatment of a matrix and the conventional treatment of a steel reinforcement in a single stretch on the stir cast composite. This material finds uses in space and transportation applications. The hybrid treatment consists of a conventional heat treatment cycle to obtain pearlite, bainite, and martensite phases in steel powder, followed by an age-hardening treatment for the Al 7075 matrix. This hybrid heat treatment resulted in improvements in the hardness and strength over the conventional aging treatment. The peak-aged hybrid specimens were subjected to natural aging in an open atmosphere for a continuous duration of 25 weeks to study the stability of the properties after peak aging. Tests of the mechanical properties such as the hardness and tensile strength along with microstructure analysis were carried out. During natural aging, the hardness of composites decreases irrespective of the quantity of the reinforcement in the composites and the type of reinforcement phase alteration during hybrid heat treatment. Also, the composites subjected to hybrid heat treatment show better resistance to natural aging compared to the conventionally aged samples. Within the group, the hybrid-treated martensite formed into a composite with 6 wt.% reinforcement showed only a 4% reduction in hardness during natural aging, which is an indication of a decent level of resistance to natural aging.

Prediction of age-hardening behaviour of LM4 and its composites using artificial neural networks

This research work highlights the prediction of hardness behaviour of age-hardened LM4 and its composites fabricated using a two-stage stir casting method with TiB2 and Si3N4. MATLAB - Artificial Neural Networks is used to predict the age-hardening behaviour of LM4 and its composites. Experiments (hardness and tensile tests) are conducted to collect data for training an ANN model as well as to investigate the effect of reinforcements and age-hardening treatment on LM4 and its composites. The results show that with an increment in the reinforcement wt%, there is an enhancement in hardness and ultimate tensile strength (UTS) values within the monolithic composites. As-cast hybrid composites display a 37 to 54% improvement in hardness compared to as-cast LM4. Heat-treated samples, specifically those treated with peak aging with MSHT and 100 °C aging, perform better than as-cast samples and other heat-treated samples in terms of UTS and hardness. Compared to as-cast LM4, MSHT, and 100 °C aged samples display an 85 to 202% increment in VHN. Hybrid composites perform better in terms of hardness, while composites with 3 wt% of TiB2 (L3TB) perform better in terms of UTS, peak aged (MSHT and 100 °C aging) L3TB display 68% increment in UTS when compared to as-cast LM4. ANN model is developed and trained with five inputs (wt% of TiB2, wt% of Si3N4, type of solutionizing, aging temperature, and aging time) and one output (VHN) using different algorithms and a different number of hidden neurons to predict the age hardening behaviour of composites. Among them, Lavenberg-Marquardt (LM) training algorithm with normalized data and 30 hidden neurons performs well and shows a least average error of 1.588364. The confirmation test confirms that the trained ANN model can predict the output with an average %error of 0.14 using unseen data.

Experimental analysis of hardness and tensile characteristics of copper reinforced AA6061 stir cast composites subjected to thermal and deformation assisted heat treatments

Aluminium alloy 6061 based composites reinforced with a varied weight percentage of copper particulates are fabricated utilizing a liquid metal stir casting technique. The collective influence of copper reinforcement, age hardening and low temperature thermomechanical treatment on AA6061 was investigated. The age hardened composites displayed better hardness and ultimate tensile strength than as cast composites. Thermomechanical treatment of the composites further enhanced the mechanical properties and hence showed better results over age hardened composites. The study revealed that an increase in the deformation enhanced the hardness and strength of the composite while the aging time to achieve the peak hardness was reduced. Both age hardened and thermomechanically treated composites with 6 wt.% copper reinforcement indicated the best peak hardness and UTS values at the lower aging temperature of 100 °C. The thermomechanically treated composite with 6 wt.% Cu, 15% deformation aged at 100 °C showed 80 and 69% increase in hardness and UTS, respectively, over as cast composite. Fracture surface analysis of the as cast, age hardened, and thermomechanical treated composites showed a mixed mode of fracture dominant with the brittle failure.

Correlating fractography with mechanical properties of microalloyed 2219Al alloys under different thermo-mechanical conditions

ABSTRACT 2219Al alloys microalloyed with varying trace contents (0–0.1 wt.%) of Cd were cast, and subjected to standard sequential thermo-mechanical processes of rolling and age-hardening treatments. Uniaxial tensile and Charpy impact tests were performed, and fractured surfaces were studied under scanning electron microscope (SEM). Variations in tensile ductility and toughness with trace additions of Cd were reported under given processing conditions. Independent influences of Cd compositions, peak-ageing treatment and rolling were investigated to identify predominant fracture modes (ductile/fibrous, brittle/cleavage or mixed) of 2219Al alloys for the first time. Salient features and fracture mechanisms as exhibited from the fractographs were further correlated with microstructural evolution, mechanical ductility and toughness. Cast 2219Al alloy exhibited typically ductile fractographs, compared to moderate level of ductility after microalloying. Lower fracture strain and toughness of peak-aged alloys were accompanied with mixed mode of fracture surfaces. Rolling resulted in fractographs of mixed mode, however with higher ductility compared to peak-aged alloys. Impact testing resulted in failure at higher strain rate, exhibiting typically brittle fractographs, correlated with the impact toughness values. Present fractographic analysis provided a structure-property correlation, to validate the susceptibility of these alloys, to different modes of failure, subjected under various loading and thermo-mechanical treatments.

Evaluation of age-hardening time on the mechanical behavior of Al-Mg-Si (Al 6063) alloy composites reinforced with alumina particles

This research attempts to evaluate the effects of age-hardening on the mechanical behavior of aluminum (6063) alloy reinforced with alumina (Al2O3) particles. Aluminum (6063)/Al2O3 composites containing 0, 5, 7, 9 and 10 wt% Al2O3 particles respectively were fabricated using double stir casting technique and representative samples from each composition were subjected to age-hardening treatment at 180 °C for 60 min, 120 min and 180 min respectively. The microstructures were evaluated using SEM while fracture toughness and tensile properties were used to evaluate the mechanical behavior of both the as-cast composites and their age-hardened counterparts. The microstructure evaluation reveals formation of coherent precipitates of Mg2Si evenly distributed in the age-hardened composites. Significant improvement in tensile strength values of 129.8, 88.6, 90.6, 137.9 and 170.6 MPa were obtained for the age-hardened composites compared to their as-cast composites with 42.2, 72.9, 81.2, 80.84 and 71.5 MPa across the series respectively. Similar trend was observed for fracture toughness with KIC values of 7.5, 5.8, 4.5, 7.8 and 9.6 MPam1/2 for age-hardened composites compared with 4.68, 4.64, 4.07, 4.06 and 3.59 MPam1/2 obtained for their as-cast composites. Age-hardening time of 180 min impart better tensile strength and fracture toughness.

Mechanical characterization of low temperature thermomechanical treated AA6061-silica sand composites

In the present work efforts are made to confirm the effects of reinforcement and thermomechanical treatment (TMT) on the mechanical properties of aluminium matrix composite (AMC) produced through stir casting technique. Silica sand particles with varying weight percentages were used to fabricate the composites and the extracted particle analysis revealed the retention of a minimum of 97% of reinforcement particles. The composites are subjected to conventional age hardening and low temperature thermomechanical treatment (LTMT) to enhance their mechanical properties. The mechanical characterization of the composites subjected to heat treatment processes include hardness and tensile tests. Nearly 20–30% increase in peak hardness, 30% decrease in aging time and 15% increase in ultimate tensile strength (UTS) was observed in LTMT treated composites as compared to age hardened composites. The best results of peak hardness and UTS of 139.76 HV and 274 MPa respectively were achieved by composite containing 6 wt.% silica sand reinforcement subjected to 15% deformation and aged at 100 °C.

Bespoke multi-step homogenization heat-treatment for a laser powder bed fused AlSi10Mg4Cu alloy synthesized via in-situ alloying

Although in-situ alloying is a flourishing technique for developing novel metal alloys for Laser Powder Bed Fusion (LPBF), the mixed alloying elements regularly segregate, causing a heterogeneous chemical composition enriched with new metastable phases. Hence, the present study focuses on the homogenization of an in-situ alloyed AlSi10Mg4Cu metal system by pursuing various heat-treatment pathways. We firstly investigated the alloy homogenization behavior upon conducting single-step heat-treatments at 485, 500, and 515 °C for set times. Experimental findings revealed that the alloy was challenging to homogenize in one-go. Heat-treating at 485 °C did not enable the complete dissolution of Cu-rich phases. By increasing temperature at 500 °C, the alloy was neither homogenized nor near-fully dense due to the untimely incipient melting of metastable Q-Al 4 Cu 2 Mg 8 Si 7 phase which caused pores. Lastly, homogenization at 515 °C led to the enhanced dissolution of θ -Al 2 Cu phase and its precursors but simultaneously exacerbated the incipient melting process of Q-Al 4 Cu 2 Mg 8 Si 7 phase observed at 500 °C. Based on the analyses of single-step homogenization behaviors, we designed a multi-step homogenization heat-treatment to dissolve the low-melting Q- phase selectively avoiding its deleterious incipient melting. The material underwent then a homogenization treatment with three consecutives steps at 495 °C for 4 h, 505 °C for 6 h and 515 °C for 6 h. The homogenization response was satisfying this time: incipient melting of Q-Al 4 Cu 2 Mg 8 Si 7 phase was annihilated, and Cu solubilization was greatly enhanced. The supersaturation level was comparable with that of the as-built condition, i.e., optimal for following age-hardening treatments. • AlSi10Mg + 4Cu alloy is produced by LPBF in-situ alloying. • Various heat-treatment pathways are investigated to homogenize the alloy chemical composition. • Single-step homogenization at 485 °C did not entirely dissolve θ -Al 2 Cu phase; • Single-step homogenization at 500 °C partially solubilized θ - phase but induced early-stage incipient melting of Q-Al 4 Cu 2 Mg 8 Si 7 phase; • Single-step homogenization conducted at 515 °C dissolved θ -Al 2 Cu while causing incipient melting of Q- phase; • Multi-step homogenization solubilized Cu segregations avoiding incipient melting of Q- phase.

Controlled precipitation and recrystallization to achieve superior mechanical properties of severely deformed Inconel 718 alloy

Severely deformed machined chips of Inconel 718 were subjected to an age-hardening treatment at 600 °C for 10 h in order to form a high fraction of γI and γII precipitates. These nano-sized precipitates help in pinning the grain boundaries and hence stabilizing the boundaries by impeding their motion at elevated temperatures. This strong pinning effect on grain boundaries is expected to result in increased strength and improved thermal stability. However, presence of a large fraction of nano-precipitates also induces precipitation hardening which results in limited ductility of the material. Therefore, in order to improve the ductility, age-hardened chips were given a subsequent heat-treatment at 700 °C, 800 °C and 900 °C for 15 min, hereafter called as post-aging heat treatment. It was anticipated that this heat-treatment at elevated temperatures would increase the dislocation mobility and result in dislocation annihilation, which can improve the ductility of aged samples. Results show that the recrystallization fraction increases with an increase in the temperature of post-aging heat treatment. Heat-treatment at 900 °C was found to result in a microstructure with highest fraction of recrystallized grains, a high fraction of coincidence site lattice (CSL) boundaries, comparatively smaller grain size and better ductility. Results also indicate that there are two counteracting effects undergoing at the same time during post-aging heat-treatment which determine the possibility of enhanced dislocation motion and associated improvement in ductility. One of these effects is related to the pinning force caused by the presence of precipitates at the boundaries. Higher pinning force by fine precipitates will lead to suppressed recrystallization by hindering the grain boundary motion and hence no improvement in ductility. Another effect is related to the driving force for recrystallization. Higher driving force, especially in the highly strained ultra-refined shear zones, will promote the reduction in overall dislocation density through recrystallization and hence leading to an improvement in ductility. Present study provides further insights into the competition between pinning and recrystallization of aged materials at elevated temperatures.

Bonding integrity of hybrid 18Ni300-17-4 PH steel using the laser powder bed fusion process for the fabrication of plastic injection mould inserts

Laser powder bed fusion (LPBF) is a metal additive manufacturing (AM) process for fabricating high-performance functional parts and tools in various metallic alloys, such as titanium, aluminium and tool steels. One specific AM application is fabricating conformal cooling channels (CCC) in plastic injection moulding tool inserts to improve cooling efficiency. This article reports the development of a novel hybrid powder-wrought alloy steel combination intended for injection mould inserts use. In this investigation, cylindrical parts made of 18Ni300 steel powder and wrought 17-4 PH steel were additively fabricated using a hybrid-build LPBF AM technique, followed by various post-build heat treatments. Standard mechanical and microstructural techniques were employed to examine the bonded powder-substrate interface. Microstructure analysis revealed defect-free, fully dense, homogenous powder-substrate fusion across a 280-µm-thick region. Tensile tests confirmed strong powder-substrate bonding due to solid solution strengthening within the region. All tensile fractures were ductile under all heat treatment conditions and occurred about 8 mm from the interface, at the side where the materials were of lower strength. The hybrid-built parts exhibited an ultimate tensile strength of 1009–1329 MPa, with 16.1–17.4% elongation at fracture. Hardness values on the AM-deposited and substrate sides were 31–55 HRC and 32–43 HRC, respectively. A direct post-build 490 °C/1 h age-hardening treatment achieved the best combination of hardness, tensile strength and ductility. The overall result demonstrates that hybrid-built powder 18Ni300-wrought 17-4 PH steel can be a material choice for manufacturing durable and high-performance injection mould inserts for high-volume production.

Artificial Neural Network for Predicting Hardness of Multistage Solutionized and Artificially Aged LM4 + TiB2 Composites

Aluminium casting alloy LM4 (EN 1706 AC-45200) composites with TiB2 (1, 2, and 3 wt.%) as reinforcements were produced using the two-stage stir casting method. OM and SEM study shows uniform and homogeneous reinforcement distribution in LM4 + TiB2 composites. As-cast composites were subjected to single-stage solution treatment at 520°C for 2 h and multistage solution treatment at 495 and 520°C for 2 and 4 h, followed by hot water quenching at 60°C and aging at 100 and 200°C for different time intervals. The hardness of as-cast and artificially aged composites were compared in both conditions. Compared to as-cast LM4 alloy, 20-45% improvement in hardness was observed for LM4 + TiB2 as-cast composites. 60-150% improvement in hardness was observed in artificially aged LM4 + 3 wt.% TiB2 composites when aged at 100 and 200°C during peak aged conditions. TEM images confirmed the presence of primary strengthening solute-rich phases after age hardening treatment such as θ’-Al2Cu and θ”-Al3Cu, which are responsible for hardness increment. An artificial neural network (ANN) model was created to predict the hardness trend of these composite samples using MATLAB R2021b, and results proved that the ANN model developed can be utilized as an effective tool to predict the hardness of treated composite samples.

Hybrid Heat Treatment for Conventionally Treatable Steel Powder Reinforced Age Hardenable Aluminium Alloy Matrix Composites and Mechanical Property Evaluation

The present work is associated with research concentrating on the innovation and use of hybrid heat treatment for eutectoid steel powder (0.8 wt%) reinforced Al-Zn-Mg (Al 7075) alloy composites. Due to high hardness, wear resistance, tensile strength and flexibility modifying heat treatment, heat treatable aluminium metal matrix composites reinforced with heat treatable hard steel particles may be the choice to explore. In this work, an attempt is made to increase hardness and tensile properties to higher levels through hybrid heat treatment, comprising simultaneous treatment to matrix and reinforcement in 3 different routes (Pearlite, Bainite and Martensite) compared to conventional age hardening treatment. SEM images and microhardness distribution witnessed the phase transformation in both matrix and reinforcement. Aging kinetics in conventional age hardening and hybrid treatments is accelerated by the increase in the quantity of reinforcement and increase in aging temperature. The improvement in hardness and tensile strength obtained by conventional age hardening path is further improved by the hybridisation path. Hybridisation route with martensite reinforcement phase shows excellent result in hardness, strength followed by bainite and pearlite path respectively in the decreasing order. In all heat treatment cycles, lower aging temperature marks greater property enhancement compared to higher temperature. Al 7075 with 6 wt% steel powder reinforced (martensite form) composite showed excellent peak age hardness, tensile strength compared to lesser quantity reinforced composites.

Precipitation Behavior and Strengthening Mechanism of Extruded 2196 Al-Cu-Li Alloy Plate during Multi-Step Age-Hardening Treatment

Precipitation Behavior and Strengthening Mechanism of Extruded 2196 Al-Cu-Li Alloy Plate during Multi-Step Age-Hardening Treatment

Exploring a hybrid manufacturing process to develop high performance age hardenable ultrafine grained AA6063/SiC nano-composite sheets

In the present work, a novel hybrid manufacturing process is established to develop high performance AA6063/SiC nano-composite sheets. The novel hybrid manufacturing process consists of cryorolling (CR) followed by warm rolling (WR). The resultant effect of the hybrid processing route on the mechanical properties, strain hardening ability, microstructural evolution and age hardening response was studied in detail. The outcomes of the hybrid processing route showed a significant enhancement in strength of CR + WR nano-composites. The improvement in strength of CR + WR is due to the combined effect of increased dislocation density, dynamic recovery, grain refinement, and aging treatment. Imparting of optimum age hardening (A) treatment (150 °C for 4 h) to CR + WR nano-composite resulted in significant enhancement of strength-ductility combination which is found to be highest among the published literature on AA6XXX/SiC composites. The mechanical properties of peak aged CR + WR composites are also found to be higher than that of CR (90% cryorolled +Peak aged)) nano composite. The scientific knowhow and governing mechanisms were established to understand the potential of hybrid manufacturing process on significant enhancement of mechanical properties and age hardening response on AA6063/SiC nano-composites.