Experimental Correlation for the Effect of Metallurgical Parameters on the Hardness of 356 and 319 Aluminum Alloys Using Minitab Software

2013 ◽  
Vol 716 ◽  
pp. 15-24
Author(s):  
Mahmoud M. Tash ◽  
S. Alkahtani
Keyword(s):  
Peak Hardness ◽  
Air Cooling ◽  
Alloying Additions ◽  
Sr Modification ◽  
Aging Period ◽  
Heat Treated ◽  
Experimental Correlation ◽  
Hardness Peak ◽  
Fe Intermetallics ◽  
Hardness Values

The present study was undertaken to investigate the effect of metallurgical parameters on the hardness and microstructural characterisations of as-cast and heat-treated 356 and 319 alloys, with the aim of adjusting these parameters to produce castings of suitable hardness and Fe-intermetallic volume fractions for subsequent use in studies relating to the machinability of these alloys. Hardness measurements were carried out on specimens prepared from 356 and 319 alloys in the as-cast and heat-treated conditions, using different combinations of grain refining, Sr-modification, and alloying additions. Aging treatments were carried out at 155 °C, 180 °C, 200 °C, and 220 °C for 4 h, followed by air cooling, as well as at 180 °C and 220 °C for 2, 4, 6, and 8 h. Peak hardness was observed in 356 alloys when aging was carried out at 180oC/4h. In the case of unmodified or modified 356 alloys containing mostly α-Fe intermetallics, aging at 180 °C up to 8h produced a sharp rise in hardness during the first two hours of aging, followed by a broad peak or plateau over the 2-8 h aging period. Aging at 220 °C revealed a hardness peak at 2h aging time for both 356 and 319 alloys. Addition of Mg to unmodified or modified 319 alloys produced a remarkable increase in hardness at all aging temperatures. This may be explained on the basis of the combined effect of Cu-and Mg-intermetallics in the 319 alloys, where hardening during aging occurs by the cooperative precipitation of Al2Cu and Mg2Si phase particles.[, ] For 356 and 384 alloys, the Mg-containing 319 alloys (~same Mg concentration as in 356 alloys) displayed higher hardness values than the 356 alloys for the aged condition, where hardening occurs by cooperative precipitation of Al2Cu and Mg2Si phase particles in 319 alloys compared to only Mg2Si precipitation in the case of 356 alloys.

Experimental Correlation between Metallurgical Parameters, Hardness and Machinability of 319 Al-Si-Cu-Mg Alloys

2011 ◽  
Vol 339 ◽  
pp. 462-476
Author(s):  
Mahmoud M. Tash ◽  
Saleh Alkahtani
Keyword(s):  
Aging Time ◽  
High Speed ◽  
Statistical Design ◽  
Magnesium Content ◽  
Air Cooling ◽  
Statistical Design Of Experiments ◽  
Alloying Additions ◽  
Sr Modification ◽  
Heat Treated ◽  
Fe Intermetallics

An attempt has been made to quantify the effects of alloying elements and aging parameters on the hardness and machinability of heat-treated 319 alloys containing α-Fe or β-Fe intermetallics An understanding of these parameters would help in selecting the metallurgical conditions required to achieve the optimum and maximum productivity at high speed machining. Hardness measurements were carried out on specimens prepared from 319 alloys in the as-cast and heat-treated conditions, using different combinations of grain refining, Sr-modification, and alloying additions. Aging treatments were carried out at 155°C, 180°C, 200°C, and 220°C for 4 h, followed by air cooling, as well as at 180°C and 220°C for 2, 4, 6, and 8 h to determine conditions under which specific hardness levels could be obtained. Statistical design of experiments is a satisfactory method for quantifying the effect of various parameters. Experimental correlations of the results obtained from the hardness measurements are analyzed and correlations that relate the alloying additions and heat treatment to the hardness of such alloys are found. Two levels of magnesium content (%Mg), volume fractions of the Fe-intermetallics (%V.F), Sr-modification (Sr-ppm), aging parameters (temperature and time) were tested: 0.1% and 0.28% for Mg, 2% and 5% for Fe-intermetallics (%V.F), 0-ppm and 200-ppm for Sr-modification, 180°C and 220°C for aging temperature and 2h. and 8h. for aging time. Experimental correlations between the metallurgical parameters and the machinability values obtained were analyzed. For this, two levels of Mg (0.1 and 0.28 wt%), Fe-intermetallics (2% and 5%), and two aging temperatures (180°C and 220°C) and aging time of 2h were selected.

scholarly journals Effect of cooling rates on T6 Treatment of B390 Aluminium-Silicon Hypereutectic alloys

2019 ◽  
Vol 293 ◽  
pp. 02001
Author(s):  
Porawit Jiandon ◽  
Sukangkana Talangkun
Keyword(s):  
Cooling Rate ◽  
Ageing Time ◽  
Eutectic Silicon ◽  
Primary Silicon ◽  
Peak Hardness ◽  
Pouring Temperature ◽  
Cooling Rates ◽  
Hardness Peak ◽  
3Si2 Phase ◽  
Hardness Values

This research aimed to study an effect of cooling rates on T6 treatment process of B390 aluminium hypereutectic alloy. B390 casting samples were casted with pouring temperature of 710°C and solidified in three different cooling rates of 33.33, 28.60 and 22.22°C/s, respectively using three metal moulds. After that samples were subjected to T6 treatment: solution treated at 510°C for 30 min and aged at 200°C at various times. However, after ageing, hardness values of as-casted samples reduced with increasing cooling rate. It was found that the specimen cooled with the highest cooling rate exhibited the highest hardness. Peak hardness values of samples cooled with cooling rate of 33.33, 28.60 and 22.22°C/s after ageing obtained from ageing time of 3, 6 and 8 hour, respectively. Furthermore, the result showed that morphology of primary silicon, eutectic silicon and Ali5(Mn, Fe)3Si2 phase presented in the aged specimen cooled with the highest cooling rate exhibited more globular, finer and distributed more evenly compared with the slower cooled samples. It can be concluded that rapid cooling rate increases concentration of a-solid solution resulted in shorter aging time.

Effect of Mg, Sr, Ti and Aging Parameters on the Mechanical Behavior of 319 Alloys in the T5 and T6 Heat Treatment

2012 ◽  
Vol 482-484 ◽  
pp. 2275-2288
Author(s):  
Saleh Alkahtani
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aging Treatment ◽  
Magnesium Content ◽  
Air Cooling ◽  
Particle Spacing ◽  
Sr Modification ◽  
Heat Treated ◽  
Negative Effect ◽  
Mg Content

In this work, the effect of metallurgical parameters (i.e. alloy chemistry and aging parameters) on the mechanical properties of 319 alloys was investigated, with the aim of adjusting these parameters to produce castings of suitable mechanical properties. An attempt has been made to quantify the effects of alloying elements (Mg, Sr, and Ti) and aging parameters on the mechanical properties of heat-treated (T5 and T6) 319 alloys. Exploring the heat treatment differences between T5 and T6 for 319 alloys would help in selecting the metallurgical conditions required to achieve the optimum and maximum mechanical properties. Aging treatments were carried out for 319 alloys in the T5- and T6-condition at 150°C, 180°C, 200°C, 220°C and 250°C for 4, 8, 16, 24 and 48 h, followed by air cooling. Aging treatment at a lower temperature of 150°C produces fine and dense precipitates having a smaller inter-particle spacing, while at higher aging temperatures, such as 250°C, the precipitates are coarser in size, less dense, and more widely dispersed. For 319 alloys, crack initiate and propagate mainly through the debonding of Si particles from the Al matrix and through the cleavage of β-iron intermetallics. Fracture of intermetallic phases in the interdendritic regions is mostly brittle, with the formation of microcracks at the Si, Cu, Fe-base intermetallics and aluminium interfaces. Experimental correlations of the results obtained from the mechanical properties measurements are analyzed and correlations that relate the alloying additions and heat treatment to the ultimate tensile strength (UTS), yield strength (YS) and total percent elongation (%E) of such alloys are found. Different levels of magnesium content (%Mg), Sr-modification (Sr-ppm), aging parameters (temperature and time) were tested. The effect of alloy additions (Mg, Sr and Ti) and aging heat treatment parameters (Temperature and Time) on the mechanical properties and alloy performance of cast and heat treated 319 alloys are investigated. It was found that the strength of 319 alloys increases with the magnesium content and decreases with the Sr-modification (Sr-ppm) and aging parameters (temperature and time). Increasing the Mg content in primary 319 alloys up to 0.45% enhances the alloy response to heat treatment in the T5 and T6 Tempers, more particularly, the T6 one. Sr-Modification of high Mg content 319 alloy in amounts of ~360 ppm leads to a noticeable decline in alloy strength due to porosity formation which counteracts the beneficial effect of the modification. Sr-modification has a negative effect on the % elongation results of Mg-content 319 alloys due to the Mg-Sr interaction in the aged-T6 conditions. However, grain refining of the Mg and Sr content 319 alloys produce sounder castings with finer grain sizes

The Natural and Artificial Aging Response of Semi-Solid Metal Processed Alloy A356

2008 ◽  
Vol 141-143 ◽  
pp. 737-742 ◽  
Author(s):  
Heinrich Möller ◽  
Gonasagren Govender ◽  
Waldo Stumpf
Keyword(s):  
Artificial Aging ◽  
Natural Aging ◽  
Peak Hardness ◽  
Time To Peak ◽  
Casting Alloys ◽  
Aging Period ◽  
Aging Response ◽  
Hardness Peak ◽  
Dendritic Microstructures ◽  
Semi Solid

The heat treatment cycles that are currently applied to semi-solid processed components are mostly those that are in use for dendritic casting alloys. These heat treatments are not necessarily the optimum treatments for non-dendritic microstructures. For rheocast alloy A356, it is shown that natural aging prior to artificial aging causes the time-to-peak-hardness to be longer compared to the time when only artificial aging is used. Furthermore, a hardness plateau is maintained during artificial aging at 180oC between 1 and 5 hours without any prior natural aging. A natural aging period as short as 1 hour results in a hardness peak (rather than a plateau) to be reached during artificial aging after 4 hours at 180oC.

Experimental Correlation between Metallurgical Parameters, Hardness and Drilling Force and Moment of Al-Si Alloys

2014 ◽  
Vol 1082 ◽  
pp. 79-84 ◽  
Author(s):  
Mahmoud M. Tash ◽  
Khaled A. Abuhasel ◽  
Saleh A. Alkahtani
Keyword(s):  
Warm Water ◽  
Drilling Force ◽  
Alloying Additions ◽  
Solution Treated ◽  
Heat Treated ◽  
Experimental Correlation ◽  
Effect Of Alloying

The present study was undertaken to investigate the effect of alloying additions and aging parameters (time and temperature) on the hardness and machinability of Al-Si alloys. Hardness, drilling force and moment and number of holes drilled/tool measurements were carried out on specimens prepared from grain refined, Sr modified and heat treated Al-Si alloys. Aging treatments were carried out for the as solution treated (SHT) specimens (after quenching in warm water) at different conditions. Hardness, drilling force and moment and number of holes drilled/tool as a function of different metallurgical parameters are analyzed to acquire an understanding of the effects of these variables and their interactions on the hardness and machinability of heat treated Al-Si alloys.

Crystallographic Differences of Metastable NI2MO in a NI-MO-AL Superalloy

1980 ◽  
Vol 38 ◽  
pp. 158-159
Author(s):  
Michael M. Kersker ◽  
E. A. Aigeltinger ◽  
J. J. IIren
Keyword(s):  
Mechanical Properties ◽  
Air Cooling ◽  
Solution Treated ◽  
Heat Treated ◽  
Metastable Compounds ◽  
Rapidly Solidified

Ni-rich alloys based on approximate ternary composition Ni-8Mo-15A1 (at%) are presently under investigation in an attempt to study the contribution, if any, of the profusion of Mo-rich NixMo metastable compounds that these alloys contain to their excellent mechanical properties. One of the alloys containing metastable NixMo precipitates is RSR 197 of composition Ni-8.96Mo-15.06A1-1.98Ta-.015Yt. The alloy was prepared at Pratt and Whitney Government Products Division, West Palm Beach, Florida, from rapidly solidified powder. The powder was canned under inert conditions and extruded as rod at 1315°C. The as-extruded rod, after air cooling, was solution treated at 1315°C for two hours, air cooled, and heat treated for one hour at 815°C, followed again by air cooling.

Effects of deep cryogenic treatment on machinability, hardness and microstructure in dry turning process of tempered steels

2020 ◽  
pp. 095440892097944
Author(s):  
Menderes Kam
Keyword(s):  
Cryogenic Treatment ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Point Of View ◽  
Turning Process ◽  
Deep Cryogenic Treatment ◽  
Dry Turning ◽  
Control Factors ◽  
Heat Treated ◽  
Hardness Values

This study investigated the effects of Deep Cryogenic Treatment (DCT) on machinability, hardness, and microstructure in dry turning process of AISI 4140 (48-51 HRc) tempered steels with ceramic cutting tools on the surface roughness (Ra). DCT process of steels has shown significant improvement in their mechanical properties. In this context, experiments were made with Taguchi L16 method and optimum values were determined. Three different values for each control factors as: different heat treated samples, cutting speeds (160, 200, 240, 280 m/min), feed rates (0.08, 0.12, 0.16, 0.20 mm/rev) were selected. As a result, the lowest Ra value was found to be 0.159 µm for the DCTT36 sample at a cutting speed of 240 m/min, a feed rate of 0.08 mm/rev. The optimum Ra value was the lowest for the DCTT36 sample compared to the other samples as 0.206 µm. The hardness values of the micro and macro were highest for the DCTT36 sample. Microstructural point of view Scanning Electron Microscopy (SEM) point of view, the DCCT36 sample showed that best results owing to its homogeneity. It was concluded that lower Ra values can be obtained with ceramic cutting tool in dry turning experiments according to the studies in the literature review. It is thought to be preferred as an alternative to cylindrical grinding process due to lower cost.

Embrittlement Behavior of Isothermally Heat-Treated T/P92 Steel at 350°C

2007 ◽  
Vol 345-346 ◽  
pp. 465-468 ◽  
Author(s):  
Ja Min Koo ◽  
Sung Yong Kim ◽  
Kee Sam Shin ◽  
Yeon Gil Jung ◽  
Sung Kang Hur
Keyword(s):  
Power Plants ◽  
Structural Integrity ◽  
Air Cooling ◽  
Boiler Tube ◽  
P92 Steel ◽  
Heat Treated

P92 steels as well as P91 are widely used as boiler tube materials of ultra super critical (USC) power plants these days. And thus embrittlement is very important for structural integrity of the USC plants. The embrittlement was observed when P92 (Modified 9Cr-1.8W-0.5Mo-V-Nb) steels were quenched to and held at the temperature of 320 to 350°C, which were the temperatures intermediate between Ms and Mf, and then air-cooled. Nearly same kind of the embrittlement had been observed with the T/P91 steels and a theory had been proposed to explain the mechanism of the embrittlement by us. From the theory, the embrittlement might be caused by the brittle martensite which is freshly formed during air-cooling. We tried to apply the theory for the embrittlement of the T/P92 steel. The behaviors of the embrittled T/P92 steel were explained well by the theory.

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