scholarly journals Influence of TiN Inclusions and Segregation on the Delayed Cracking in NM450 Wear-Resistant Steel

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 21
Author(s):  
Jingjing Liu ◽  
Denghui Liu ◽  
Xiurong Zuo ◽  
Lihua Liu ◽  
Qiangjun Yan
Keyword(s):  
Electron Microscopy ◽  
High Hardness ◽  
High Strength ◽  
Total Elongation ◽  
Resistant Steel ◽  
Wear Resistant ◽  
Transmission Electron ◽  
Cutting Surface ◽  
Delayed Cracking ◽  
Reduction Of Area

High-strength, wear-resistant steel often suffers from delayed cracking after flame cutting. Delayed cracking can lead to extremely harmful sudden brittle fracture; therefore, it is necessary to study the formation of delayed cracking in high-strength steel. This work investigated the influence of TiN inclusions and segregation on the delayed cracking in NM450 wear-resistant steel by optical microscopy, scanning electron microscopy, X-ray diffraction, transmission electron microscopy and electron backscattered diffractometer methods. The results indicated that the delayed cracks originated from the segregation zones (SZs) containing multiple high-hardness segregation bands. The tensile strength of the SZ specimens was higher than that of non-segregation zone (NSZ) specimens, while the total elongation and reduction of area of the SZ specimens were relatively lower compared with the NSZ specimens. Therefore, the delayed cracking on the flame cutting surface of the NM450 steel plate was attributed to the existence of SZs that contain a high density of dislocations and considerable micro-sized TiN inclusions.

scholarly journals Effect of Aging Time on Crushing Performance of Al-0.5Mg-0.4Si Alloy for Safety Components of Automobile

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 608
Author(s):  
Jinkun Lu ◽  
Haichun Jiang ◽  
Lingying Ye ◽  
Daxiang Sun ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Tensile Test ◽  
Aging Time ◽  
Uniform Elongation ◽  
Total Elongation ◽  
Localized Deformation ◽  
Ductility Index ◽  
Transmission Electron ◽  
The Difference

The effect of aging time on the crushing performance of Al-0.5Mg-0.4Si alloy used for safety components of automobile was investigated by tensile test and crush test. Moreover, the microstructure of the alloy was investigated by transmission electron microscopy (TEM). The results show that the localized deformation ductility index, ΔAabs, which is defined as the difference between total elongation and uniform elongation, of Al-0.5Mg-0.4Si alloy is 6.5%, 7.0% and 8.5%, respectively, after being aged at 210 °C for 1, 3 and 6 h, and this tendency is the same as that of the crushing performance. The spacing of grain boundary precipitates (GBPs) from TEM results are found to be 94.9, 193.6 and 408.2 nm after being aged at 210 °C for 1, 3 and 6 h, respectively, and this tendency is same to that of ΔAabs. A mechanism about the relation between the spacing of GBPs and the ductility index ΔAabs has been proposed based on localized deformation around GBPs. With the increase of GBPs spacing, the ΔAabs increases, and the crushing performance is improved.

scholarly journals Tensile Behavior and Deformation Mechanism of Fe-Mn-Al-C Low Density Steel with High Strength and High Plasticity

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 897 ◽  
Author(s):  
Jingyu Pang ◽  
Zhanming Zhou ◽  
Zhengzhi Zhao ◽  
Di Tang ◽  
Juhua Liang ◽  
...  
Keyword(s):  
Solution Treatment ◽  
High Strength ◽  
Total Elongation ◽  
Tensile Behavior ◽  
Gradual Transition ◽  
High Plasticity ◽  
Low Density ◽  
Hardening Behavior ◽  
Transmission Electron ◽  
Strain Hardening Behavior

Tensile behavior and plastic deformation mechanisms of Fe-22.8Mn-8.48Al-0.86C low-density steel were studied in this thesis. After solution treatment 1100 °C for 1 h; the steels obtained an excellent combination in mechanical properties; with tensile strength of 757.4 MPa and total elongation of 68%; which were attributed to the existence of annealing twins in austenite. The present steel presented a multiple stage strain hardening behavior which was associated with the changes of such dislocation substructures. With the increase of strain, the gradual transition from tangled dislocations to dense dislocation walls and microbands was found in (the transmission electron microscopy) TEM microstructures. Due to the influence of the evolution of the microstructure during the deformation process, the work hardening behavior of the experimental steel shows three distinct stages.

scholarly journals Investigation of Interfacial Layer for Friction Stir Scribe Welded Aluminum to Steel Joints

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Kaifeng Wang ◽  
Piyush Upadhyay ◽  
Yuxiang Wang ◽  
Jingjing Li ◽  
Xin Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Driving Force ◽  
Bond Formation ◽  
Welding Process ◽  
High Strength ◽  
Bimaterial Interface ◽  
Joint Interface ◽  
Friction Stir ◽  
Transmission Electron ◽  
Steel Joints

Friction stir scribe (FSS) welding as a recent derivative of friction stir welding (FSW) has been successfully used to fabricate a linear joint between automotive Al and steel sheets. It has been established that FSS welding generates a hook-like structure at the bimaterial interface. Beyond the hook-like structure, there is a lack of fundamental understanding on the bond formation mechanism during this newly developed FSS welding process. In this paper, the microstructures and phases at the joint interface of FSS welded Al to ultra-high-strength steel were studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that both mechanical interlocking and interfacial bonding occurred simultaneously during the FSS welding process. Based on SEM observations, a higher diffusion driving force in the advancing side was found compared to the retreating side and the scribe swept zone, and thermally activated diffusion was the primary driving force for the interfacial bond formation in the scribe swept region. The TEM energy-dispersive X-ray spectroscopy (EDXS) revealed that a thin intermetallic compound (IMC) layer was formed through the interface, where the thickness of this layer gradually decreased from the advancing side to the retreating side owing to different material plastic deformation and heat generations. In addition, the diffraction pattern (or one-dimensional fast Fourier transform (FFT) pattern) revealed that the IMC layer was composed of Fe2Al5 or Fe4Al13 with a Fe/Al solid solution depending on the weld regions.

scholarly journals Effect of Tempering Temperature on Microstructures and Wear Behavior of a 500 HB Grade Wear-Resistant Steel

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 45 ◽  
Author(s):  
Erding Wen ◽  
Renbo Song ◽  
Wenming Xiong
Keyword(s):  
Electron Microscopy ◽  
Wear Resistance ◽  
Impact Toughness ◽  
Wear Behavior ◽  
Temper Embrittlement ◽  
Surface Hardness ◽  
Resistant Steel ◽  
Tempering Temperature ◽  
Wear Resistant ◽  
The Impact

The microstructure and wear behavior of a 500 Brinell hardness (HB) grade wear-resistant steel tempered at different temperatures were investigated in this study. The tempering microstructures and wear surface morphologies were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The relationship between mechanical properties and wear resistance was analyzed. The microstructure of the steel mainly consisted of tempered martensite and ferrite. Tempered troosite was obtained when the tempering temperature was over 280 °C. The hardness decreased constantly with the increase of tempering temperature. The same hardness was obtained when tempered at 260 °C and 300 °C, due to the interaction of Fe3C carbides and dislocations. The impact toughness increased first and reached a peak value when tempered at 260 °C. As the tempering temperature was over 260 °C, carbide precipitation would occur along the grain boundaries, which led to temper embrittlement. The best wear resistance was obtained when tempered at 200 °C. At the initiation of the wear test, surface hardness was considered to be the dominant influencing factor on wear resistance. The effect of surface hardness improvement on wear resistance was far greater than the impact toughness. With the wear time extending, the crushed quartz sand particles and the cut-down burs would be new abrasive particles which would cause further wear. Otherwise, the increasing contact temperature would soften the matrix and the adhesive wear turned out to be the dominant wear mechanism, which would result in severe wear.

Effect of Processing Route on Mechanical Behavior of C-Mn Multiphase High Strength Cold Rolled Steel

2007 ◽  
Vol 539-543 ◽  
pp. 4375-4380
Author(s):  
Dagoberto Brandão Santos ◽  
Élida G. Neves ◽  
Elena V. Pereloma
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Mechanical Behavior ◽  
Quantitative Relationship ◽  
High Strength ◽  
Microstructural Characterization ◽  
Processing Route ◽  
Accelerated Cooling ◽  
Microstructural Parameters ◽  
Transmission Electron

The multiphase steels have complex microstructures containing polygonal ferrite, martensite, bainite, carbide and a small amount of retained austenite. This microstructure provides these steels with a high mechanical strength and good ductility. Different thermal cycles were simulated in the laboratory in order to create the microstructures with improved mechanical properties. The samples were heated to various annealing temperatures (740, 760 or 780°C), held for 300 s, and then quickly cooled to 600 or 500°C, where they were soaked for another 300 s and then submitted to the accelerated cooling process, with the rates in the range of 12-30°C/s. The microstructure was examined at the end of each processing route. The mechanical behavior evaluation was made by microhardness testing. The microstructural characterization involved optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM) with electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM). The use of multiple regression analysis allowed the establishment of quantitative relationship between the microstructural parameters, cooling rates and mechanical properties of the steel.

Electron Microscope Investigation of PVD Coated Aluminium Alloy Surface Layer

2012 ◽  
Vol 186 ◽  
pp. 192-197 ◽  
Author(s):  
Tomasz Tański ◽  
Krzysztof Labisz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Layer ◽  
Electron Microscope ◽  
Aluminium Alloy ◽  
Aluminium Alloys ◽  
Wear Resistant ◽  
Electron Microscope Investigation ◽  
Microscope Investigation ◽  
Transmission Electron

The purpose of this work is electron microscope investigation of the Ti/TiCN/TiAlN and Cr/CrN/CrN coatings deposited by PVD process. The investigations were performed using scanning and transmission electron microscopy for the microstructure determination. By mind of the transmission electron microscopy the high resolution and phase determination was possible to obtain. The morphology was studied as well the lattice parameters for the layer matrix and substrate phase identification using diffraction methods was applied. After the coating of the aluminium alloys AlSi9Cu and AlSi9Cu4 with the selected coatings there are crystallites detected with the size of several tenth of diameter. The investigated samples were examined metallographically using electron microscope with different image techniques, also EDS microanalysis and electron diffraction was made. As an implication for the practice a new layer sequence can be possible to develop, based on PVD technique. Some other investigation should be performed in the future, but the knowledge found in this research shows an interesting investigation direction. The originality and value of this combination of TEM investigation for PVD deposited surface lasers on aluminium alloys makes the investigation very attractive for automotive and other industry branches. Some practical implications and employment of the surface treatment technology for elements, made from tool materials, with the PVD and CVD methods, to obtain the high wear resistant coatings, makes it possible to improve the properties of these materials by – among others – decreasing for example their friction coefficient, microhardness increase, improvement of the tribological contact conditions in practical use. One original value is it also to applied the PVD method on a common material like aluminium alloy. The double layer coatings worked out In the PVD process on the Al0Si-Cu alloys substrate hale the following configuration of the layers: bottom layer/gradient layer/wear resistant hard surface layer.

Study on the Microstructure and Properties of Low Cost TiFeAl Alloy

2013 ◽  
Vol 477-478 ◽  
pp. 1288-1292
Author(s):  
Bo Long Li ◽  
Tong Liu ◽  
Jie Yuan ◽  
Zuo Ren Nie
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Low Cost ◽  
High Strength ◽  
Al Alloys ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
Β Phase ◽  
Transmission Electron ◽  
Solution Strengthening

The high strength and low cost Ti-Fe based alloy was produced by double vacuum induction melting method followed by hot deformation. The microstructure has been investigated by Optical Microscopy, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The microstructure of as-forged alloy is composed of α and β phase without the precipitation of TiFe intermetallic compound. The Ti-Fe-Al alloys show good comprehensive mechanical properties, demonstrating ultimate tensile strength of 1100MPa and elongation above10%. The results indicate the Fe is a good candidate for solution strengthening and simultaneously increasing ductility in titanium alloys. Effect of the Fe and Al elements on the microstructure and mechanical properties have been discussed.

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