scholarly journals Determination of step aging effective modes of a stamped alloy for hot deformation

2021 ◽  
Vol 99 (3) ◽  
pp. 32-39
Author(s):  
V.Ya. Grabovsky ◽  
◽  
V.I. Kanyuka ◽  
O.V. Lysytsia ◽  
◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Impact Strength ◽  
Spherical Particles ◽  
Simultaneous Increase ◽  
High Temperature Strength ◽  
Regression Equations ◽  
Two Stage ◽  
Temperature Impact

Using the method of mathematical planning of the experiment, the influence of two-stage (low-temperature + high-temperature) aging on the hardness and high-temperature (750 °C) impact strength of a stamped alloy ХН35ВТЮ (EK39) for hot pressing of metals was investigated. The need to increase the high-temperature impact strength of the alloy is a significant decrease (failure) with increasing test temperature from room temperature to 700… 750 °C. To isolate the particles of the reinforcing γ′-phase of the Ni3(Al,Ti) type during aging, the alloy was previously hardened in oil from a temperature of 1150 °C. Determination of the most effective modes of two-stage aging was performed using a small replica of the orthogonal plan of the second order type 24-1. The first (low-temperature) stage corresponds to the beginning of spinodal decay of supersaturated solid solution at the stage of formation of Guinness-Preston zones, and the second (high-temperature) - to the formation of particles of stable γ′-phase type Ni3(Ti,Al). Temperature and aging time on each step varied. According to the planning matrix, regression equations were calculated, and additional experiments were performed to determine the modes of step aging, which provide the alloy with a higher level of selected properties compared to the recommended single aging (780 °C, 10 hours). According to the obtained regression equations, the change in the aging temperature at the second stage of aging does not affect the hardness of the alloy within its variation (750 °C–800 °C). The effect on impact strength of changes in temperature (650 °C–700 °C) and holding time (2–6 hours) at the first stage of aging is also insignificant. According to the results of processing and analysis of experimental data, it is established that the increase of high-temperature impact strength from 38 to 120 J/cm2 (while maintaining hardness and high-temperature strength at the same level) is achieved after step aging 700 °C, 20 hours + 750 °C, 2 hours. The increase in hardness from 29 to 33 HRC with a simultaneous increase in impact strength to 55 J/cm2 provides step aging of 725 °C, 10 hours + 775 °C, 6 hours. According to the results of electron microscopic study of the microstructure, it was found that the achieved level of impact strength after step aging is provided by increasing the dispersion of spherical particles of the γ′-phase of the type Ni3(Al,Ti). The increase in hardness is due to a more uniform volume distribution and a smaller cross-sectional scatter of γ′-phase particles. Keywords: aging, dispersion hardening, impact strength, microstructure, stamping tool.

scholarly journals Effects of Double-Ageing Heat Treatments on the Microstructure and Mechanical Behaviour of a Ti-3.5Al-5Mo-4V Alloy

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 209
Author(s):  
Xuanming Ji ◽  
Panpan Ge ◽  
Song Xiang ◽  
Yuanbiao Tan
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Low Temperature ◽  
Mechanical Behaviour ◽  
Ageing Time ◽  
Two Stage ◽  
Ageing Treatment ◽  
Ω Phase ◽  
Α Phase ◽  
Temperature Ageing

In this work, the effect of double-ageing heat treatments on the microstructural evolution and mechanical behaviour of a metastable β-titanium Ti-3.5Al-5Mo-4V alloy is investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The double-ageing treatments are composed of low-temperature pre-ageing and high-temperature ageing, where the low-temperature pre-ageing is conducted at 300 °C or 350 °C for different times, and the high-temperature ageing is conducted at 500 °C for 8 h. The results show that the phase transformation sequence is altered with the time spent during the first ageing stage, the isothermal ω phase is precipitated in the pre-ageing process of the alloy at 300 °C and 350 °C with the change in the ageing time, and the ω phase is finally transformed into the α phase with the extension of pre-ageing time. The existence time of the ω phase is shortened as the pre-ageing temperature increases. The microhardness of the alloy increases with increasing pre-ageing time and temperature. Compared with single-stage ageing, the ω phase formed in the pre-ageing stage changes the response to subsequent high-temperature ageing. After the two-stage ageing treatment, the precipitation size of the α phase is obviously refined after the double-ageing treatment. A microhardness test shows that the microhardness of the two-stage aged alloy increases with extended pre-ageing time.

Influence of Al-Cu-Mn-Fe-Ti Alloy Composition and Production Parameters of Extruded Semi-Finished Products on their Structure and Mechanical Properties

2017 ◽  
Vol 265 ◽  
pp. 456-462 ◽  
Author(s):  
P.L. Reznik ◽  
Mikhail Lobanov
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Thermal Treatment ◽  
Low Temperature ◽  
Room Temperature ◽  
High Temperature Strength ◽  
Ti Alloy ◽  
Low Temperature Annealing ◽  
Annealing Conditions ◽  
Concentration Changes

Studies have been conducted as to the effect of Cu, Mn, Fe concentration changes in Al-Cu-Mn-Fe-Ti alloy, the conditions of thermal and deformational treatment of ingots and extruded rods 40 mm in diameter on the microstructure, phase composition and mechanical properties. It has been determined that changing Al-6.3Cu-0.3Mn-0.17Fe-0.15Ti alloy to Al-6.5Cu-0.7Mn-0.11Fe-0.15Ti causes an increase in the strength characteristics of extruded rods at the room temperature both after molding and in tempered and aged conditions, irrespective of the conditions of thermal treatment of the initial ingot (low-temperature annealing 420 °С for 2 h, or high-temperature annealing at 530 °С for 12 h). Increasing the extruding temperature from 330 to 480 °С, along with increasing Cu, Mn and decreasing Fe in the alloy Al-Cu-Mn-Ti, is accompanied by the increased level of ultimate strength in a quenched condition by 25% to 410 MPa, irrespective of the annealing conditions of the original ingot. An opportunity to apply the Al-6.3Cu-0.3Mn-0.17Fe-0.15Ti alloy with low-temperature annealing at 420 °С for 2 h and the molding temperature of 330 °С has been found to produce rods where, in the condition of full thermal treatment (tempering at 535 °С + aging at 200 °С for 8 hours), a structure is formed that ensures satisfactory characteristics of high temperature strength by resisting to fracture for more than 100 hours at 300 °С and 70 MPa.

Preparation of a silver nanoparticle-based dual-functional sensor using a complexation–reduction method

2015 ◽  
Vol 17 (33) ◽  
pp. 21243-21253 ◽  
Author(s):  
Fwu-Long Mi ◽  
Shao-Jung Wu ◽  
Wen-Qi Zhong ◽  
Cheng-Yu Huang
Keyword(s):  
Silver Nanoparticles ◽  
High Temperature ◽  
Low Temperature ◽  
Silver Nanoparticle ◽  
Reduction Method ◽  
Ag Nps ◽  
Two Stage ◽  
Temperature Reduction ◽  
Dual Functional

A dual-functional sensor based on silver nanoparticles was synthesized by a two-stage procedure consisting of a low-temperature chitosan–Ag+ complexation followed by a high-temperature reduction of the complex to form chitosan-capped silver nanoparticles (CS-capped Ag NPs).

scholarly journals Molybdenum Disilicide Composites Produced by Plasma Spraying

1998 ◽  
Author(s):  
R.G. Castro ◽  
H. Kung ◽  
K.J. Hollis ◽  
A.H. Bartlett
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Plasma Spraying ◽  
Creep Resistance ◽  
Elevated Temperatures ◽  
Powder Processing ◽  
National Laboratory ◽  
Molybdenum Disilicide ◽  
High Temperature Strength ◽  
Structural Applications

Abstract The intermetallic compound, molybdenum disilicide (MoSi2) is being considered for high temperature structural applications because of its high melting point and superior oxidation resistance at elevated temperatures. The lack of high temperature strength, creep resistance and low temperature ductility has hindered its progress for structural applications. Plasma spraying of coatings and structural components of MoSi2-based composites offers an exciting processing alternative to conventional powder processing methods due to superior flexibility and the ability to tailor properties. Laminate, discontinuous and in situ reinforced composites have been produced with secondary reinforcements of Ta, A1203, SiC, Si3N4 and Mo5Si3. Laminate composites, in particular, have been shown to improve the damage tolerance of MoSi2 during high temperature melting operations. A review of research which as been performed at Los Alamos National Laboratory on plasma spraying of MoSi2-based composites to improve low temperature fracture toughness, thermal shock resistance, high temperature strength and creep resistance will be discussed.

Study on Performance of PP/POE In Situ Compatibilization

2012 ◽  
Vol 468-471 ◽  
pp. 1053-1057
Author(s):  
Yun Feng Yang ◽  
Guo Sheng Hu ◽  
Xing Lin Ren
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Impact Strength ◽  
Room Temperature ◽  
Dicumyl Peroxide ◽  
Maximum Value ◽  
Trimethylolpropane Triacrylate ◽  
In Situ Compatibilization ◽  
Temperature Impact

By the in situ compatibilization, PP/POE blends were prepared with dicumyl peroxide (DCP) as initiator, Trimethylolpropane triacrylate (TMPTA) as co-during systems and the metallocene polyolef in elastomers ploy (ethylene-1-octene) (POE) as toughening rubber. The effects of additive amount for TMPTA、POE on the mechanical properties were studied. The results showed that the maximum value of the room-temperature and low-temperature impact strength for the composite was reached to 52.03KJ/m2 and 37.29KJ/m2, and the elongationfor was reached to 482.74%.

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