scholarly journals Effect of the Austempering Process on the Microstructure and Mechanical Properties of 27MnCrB5-2 Steel

2017 ◽  
Vol 62 (2) ◽  
pp. 643-651 ◽  
Author(s):  
A. Morri ◽  
L. Ceschini ◽  
M. Pellizzari ◽  
C. Menapace ◽  
F. Vettore ◽  
...  

AbstractThe effect of austempering parameters on the microstructure and mechanical properties of 27MnCrB5-2 steel has been investigated by means of: dilatometric, microstructural and fractographic analyses; tensile and Charpy V-notch (CVN) impact tests at room temperature and a low temperature.Microstructural analyses showed that upper bainite developed at a higher austempering temperature, while a mixed bainitic-martensitic microstructure formed at lower temperatures, with a different amount of bainite and martensite and a different size of bainite sheaf depending on the temperature. Tensile tests highlighted superior yield and tensile strengths (≈30%) for the mixed microstructure, with respect to both fully bainitic and Q&T microstructures, with only a low reduction in elongation to failure (≈10%). Impact tests confirmed that mixed microstructures have higher impact properties, at both room temperature and a low temperature.

2018 ◽  
Vol 284 ◽  
pp. 615-620 ◽  
Author(s):  
R.M. Baitimerov ◽  
P.A. Lykov ◽  
L.V. Radionova

TiAl6V4 titanium base alloy is widely used in aerospace and medical industries. Specimens for tensile tests from TiAl6V4 with porosity less than 0.5% was fabricated by selective laser melting (SLM). Specimens were treated using two heat treatment procedures, third batch of specimens was tested in as-fabricated statement after machining. Tensile tests were carried out at room temperature. Microstructure and mechanical properties of SLM fabricated TiAl6V4 after different heat treatments were investigated.


Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1448 ◽  
Author(s):  
Mattia Franceschi ◽  
Luca Pezzato ◽  
Claudio Gennari ◽  
Alberto Fabrizi ◽  
Marina Polyakova ◽  
...  

High Silicon Austempered steels (AHSS) are materials of great interest due to their excellent combination of high strength, ductility, toughness, and limited costs. These steel grades are characterized by a microstructure consisting of ferrite and bainite, accompanied by a high quantity retained austenite (RA). The aim of this study is to analyze the effect of an innovative heat treatment, consisting of intercritical annealing at 780 °C and austempering at 400 °C for 30 min, on the microstructure and mechanical properties of a novel high silicon steel (0.43C-3.26Si-2.72Mn wt.%). The microstructure was characterized by optical and electron microscopy and XRD analysis. Hardness and tensile tests were performed. A multiphase ferritic-martensitic microstructure was obtained. A hardness of 426 HV and a tensile strength of 1650 MPa were measured, with an elongation of 4.5%. The results were compared with those ones obtained with annealing and Q&T treatments.


2007 ◽  
Vol 560 ◽  
pp. 29-34 ◽  
Author(s):  
Emmanuel Gutiérrez C. ◽  
Armando Salinas-Rodríguez ◽  
Enrique Nava-Vázquez

The effects of heating rate and annealing temperature on the microstructure and mechanical properties of cold rolled Al-Si, low C non-oriented electrical steels are investigated using SEM metallography and uniaxial tensile tests. The experimental results show that short term annealing at temperatures up to 850 °C result in microstructures consisting of recrystallized ferrite grains with sizes similar to those observed in industrial semi-processed strips subjected to long term batch annealing treatments. Within the temperature range investigated, the grain size increases and the 0.2% offset yield strength decreases with increasing temperature. It was observed that the rate of change of grain size with increasing temperature increases when annealing is performed at temperatures greater than Ac1 (~870 °C). This effect is attributed to Fe3C dissolution and rapid C segregation to austenite for annealing temperatures within the ferrite+austenite phase field. This leads to faster ferrite growth and formation of pearlite when the steel is finally cooled to room temperature. The presence of pearlite at room temperature decreases the ductility of samples annealed at T > Ac1.


2020 ◽  
Vol 993 ◽  
pp. 161-165
Author(s):  
Yi Zhang ◽  
Xiao Hui Feng ◽  
Yuan Sheng Yang

The effect of Ca on the microstructure and mechanical properties of directionally solidified (DSed) Mg-3Zn-xCa alloys (x=0.2,0.5,0.8wt.%) was investigated in the present work. The results showed that the DSed samples with the growth rate of 120 μm/s had columnar dendritic structures and the primary dendritic arm spacing (PDAS) decreased with the content of Ca increase. The TEM result indicated that the growth orientation of the DSed Mg-Zn-xCa alloys was , which was independent of the content of Ca. The tensile tests at room temperature showed that the mechanical properties of the DSed Mg-Zn-xCa alloys were strongly affected by the content of Ca. The addition of Ca remarkably improved the ultimate tensile strength (UTS) and the yield strength (YS), while dramatically reduced the elongation (El). Prismatic slip and twinning were the main deformation mechanisms in tensile tests.


2020 ◽  
Vol 993 ◽  
pp. 351-357
Author(s):  
Ming Yu Zhao ◽  
Xiao Yun Song ◽  
Wen Jing Zhang ◽  
Yu Wei Diao ◽  
Wen Jun Ye ◽  
...  

The Ti-6.5Al-2Sn-4Zr-1.5Mo-2Nb-0.25Fe-0.2Si (wt%) alloy is a novel two-phase high temperature alloy for short-term application. The effects of different heat treatments on the microstructure and mechanical properties were investigated through electron probe microanalysis (EPMA), optical microcopy (OM), scanning electron microscope (SEM), electron backscattered diffraction (EBSD) and tensile tests at room temperature and 650°C. Subjected to the annealing treatment at α+β region (1010 °C/2 h, FC to 990 °C+990 °C/2 h, AC), the microstructure was composed of bimodal structure, which consists of equiaxed primary α (αp) phase and lamellar transformed β (βt) structure. As a strong β stabilizer, the content of Fe in α phase is much less than that in β phase. Annealing at β region (1040 °C/2 h, AC) resulted in the formation of widmannstatten structure, consisting of coarse raw β grain and secondary α phase precipitated on the β grain. With respect to the tensile property, different heat-treated alloys obtained similar strength. However, widmannstatten structure was characterized by lower plasticity, with the elongation only half that of bimodal structure. The fracture characteristics at room temperature for the alloy with bimodal structure and widmannstatten structure are dominated by ductile fracture and cleavage fracture, respectively.


2014 ◽  
Vol 1035 ◽  
pp. 303-306
Author(s):  
Xiao Ya Chen ◽  
Quan An Li ◽  
Qing Zhang ◽  
Jun Chen ◽  
Hui Zhen Jiang

The microstructure and mechanical properties of Mg-6Al-1Zn-0.9Y-1.8Gd alloy have been studied by micro-analysis and tensile tests. The results showed that the alloy mainly consists of Mg matrix, Al2Y, Mg17Al12and Al2Gd. The best tensile strength of the alloy was 255 Mpa at room temperature, and the alloy still had the very high mechanical property at high temperature.


2010 ◽  
Vol 152-153 ◽  
pp. 197-201 ◽  
Author(s):  
Qing Zhang ◽  
Quan An Li ◽  
Xiao Tian Jing ◽  
Xing Yuan Zhang

The effects of yttrium on the microstructure and mechanical properties of magnesium alloy AZ81 have been investigated by alloy preparation, microstructure analysis and tensile tests. The results show that proper content of yttrium addition can obviously refine the microstructure of magnesium alloy AZ81, reduce the amount of β-Mg17Al12 phase, lead to the precipitation of Al2Y phase and improve the mechanical properties. After solid solution and aging treatment, the tensile strength and elongation of the alloy increase at first and then decrease with the increase of yttrium content, and reach the maxima at 2%Y. At room temperature, the maxima are 277MPa and 10.9% respectively. At 150 , the maxima are 220MPa and 12.4% respectively.


2013 ◽  
Vol 750-752 ◽  
pp. 611-614
Author(s):  
Zhi Chen ◽  
Quan An Li ◽  
Wen Jian Liu ◽  
Xiao Jie Song

The Mg-12Gd-2Y-2Sm-0.5Zr (wt.%) alloy was prepared by induction melting. After solution and aging treatment, the microstructure and mechanical properties of alloy was investigated by optical microscope, XRD and tensile tests. The results show that the aged alloy is mainly composed by α-Mg matrix, Mg24Y5 and Mg5Gd phase, and these precipitated phases distribute in the grain dispersively. The mechanical properties of alloy were tested at room temperature and 200-300°C.


2013 ◽  
Vol 310 ◽  
pp. 124-128 ◽  
Author(s):  
Xiao Jun Zhang ◽  
Xin Long Chang ◽  
Shi Ying Zhang ◽  
Jie Tang Zhu

In order to investigate low temperature mechanical characteristics of HTPB (hydroxy-terminated polybutadiene binder) propellant, uniaxial tensile tests at both the low temperature and room temperature after short storage at low temperature were conducted and SEM (scanning electron microscopy) was used to observe fracture surfaces. The mechanical properties and stress-strain curves were obtained. The experimental results show that matrix tearing and particle brittle fracture occur in low temperature tensile test, but only particle/matrix interface de-wetting in room temperature tensile test. Low temperature stress-strain curves of propellant appear obviously yield region, and the yield degree is involved to the low temperature value. The low temperature mechanical properties such as maximum tensile stress, elastic modulus and strain at maximum stress against temperature are different from room temperature mechanical properties.


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