scholarly journals Simultaneously Enhanced Strength, Toughness and Ductility of Cast 40Cr Steels Strengthened by Trace Biphase TiCx-TiB2 Nanoparticles

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 707 ◽  
Author(s):  
Chuan-Lu Li ◽  
Feng Qiu ◽  
Fang Chang ◽  
Xu-Min Zhao ◽  
Run Geng ◽  
...  
Keyword(s):  
Cast Steel ◽  
Casting Process ◽  
Difficult Problem ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Pinning Effect ◽  
Cast Steels ◽  
Bainite Structure ◽  
Fine Microstructure

Simultaneously improving the strength, toughness, and ductility of cast steels has always been a difficult problem for researchers. Biphase TiCx-TiB2 nanoparticle-reinforced cast steels are prepared by adding in situ nanosized biphase TiCx-TiB2/Al master alloy during the casting process. The experimental results show that a series of significant changes take place in the microstructure of the steel: the ferrite-pearlite structure of the as-cast steels and the bainite structure of the steels after heat treatment are refined, the grain size is reduced, and the content of nanoparticles is increased. Promotion of nucleation and inhibition of dendrite growth by biphase TiCx-TiB2 nanoparticles leads to a refinement of the microstructure. The fine microstructure with evenly dispersed nanoparticles offers better properties [yield strength (1246 MPa), tensile strength (1469 MPa), fracture strain (9.4%), impact toughness (20.3 J/cm2) and hardness (41 HRC)] for the steel with 0.018 wt.% biphase TiCx-TiB2 nanoparticles, which are increased by 15.4%, 31.2%, 4.4%, 11.5%, and 7.9% compared with the 40Cr steels. The higher content of nanoparticles provides higher strengths and hardness of the steel but are detrimental to ductility. The improved properties may be attributed to fine grain strengthening and the pinning effect of nanosized carbide on dislocations and grain boundaries. Through this work, it is known that the method of adding trace (0.018 wt.%) biphase TiCx-TiB2 nanoparticles during casting process can simultaneously improve the strength, toughness, as well as ductility of the cast steel.

In Situ Preparation and Mechanical Properties of (ZrB2+ZrC)/Zr3[Al(Si)]4C6 Composites

2014 ◽  
Vol 602-603 ◽  
pp. 438-442
Author(s):  
Lei Yu ◽  
Jian Yang ◽  
Tai Qiu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Bending Strength ◽  
Coefficient Of Thermal Expansion ◽  
Raw Materials ◽  
Linear Increase ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Uniform Microstructure

Fully dense (ZrB2+ZrC)/Zr3[Al (Si)]4C6 composites with ZrB2 content varying from 0 to 15 vol.% and fixed ZrC content of 10 vol.% were successfully prepared by in situ hot-pressing in Ar atmosphere using ZrH2, Al, Si, C and B4C as raw materials. With the increase of ZrB2 content, both the bending strength and fracture toughness of the composites increase and then decrease. The synergistic action of ZrB2 and ZrC as reinforcements shows significant strengthening and toughing effect to the Zr3[Al (Si)]4C6 matrix. The composite with 10 vol.% ZrB2 shows the optimal mechanical properties: 516 MPa for bending strength and 6.52 MPa·m1/2 for fracture toughness. With the increase of ZrB2 content, the Vickers hardness of the composites shows a near-linear increase from 15.3 GPa to 16.7 GPa. The strengthening and toughening effect can be ascribed to the unique mechanical properties of ZrB2 and ZrC reinforcements, the differences in coefficient of thermal expansion and modulus between them and Zr3[Al (Si)]4C6 matrix, fine grain strengthening and uniform microstructure derived by the in situ synthesis reaction.

Study on Microstructure and Impact Toughness of In Situ Mg2Si Particle Reinforced Al-Si Matrix Composites

2012 ◽  
Vol 557-559 ◽  
pp. 215-218
Author(s):  
Niu Can Liu ◽  
Guang Sheng Kang ◽  
Zhong Xia Liu
Keyword(s):  
Impact Toughness ◽  
Fine Particles ◽  
Matrix Composites ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Average Size ◽  
Different Content ◽  
The Impact

The microstructure and impact toughness of in-situ Mg2Si/Al-Si composites were studied in the different content of Sb. The results show that Sb can improve the microstructure and impact toughness of Mg2Si/Al-Si composites. When the content of Sb is 0.4%, the morphology of primary Mg2Si changes from dendrites to fine particles, the average size of Mg2Si particles is refined from 52μm to 25μm, and the impact toughness of the composites increases from 6.3572J/cm2 to 11.4394J/cm2. The improvement of impact toughness can be attributed to the fine-grain strengthening. However, excessive Sb is disadvantageous to the modification of the composites.

Study on Rheo-Continuous Casting of Al-Si A356 (EN AC4200) Alloys

2016 ◽  
Vol 682 ◽  
pp. 220-225
Author(s):  
Do Minh Duc ◽  
Nguyen Hong Hai
Keyword(s):  
Continuous Casting ◽  
Continuous Process ◽  
Casting Machine ◽  
Casting Process ◽  
High Rate ◽  
Casting Method ◽  
Pouring Temperature ◽  
Cooling Slope ◽  
Fine Grain ◽  
Fine Microstructure

Rheo-continuous casting method is a combination of rheo- and continuous castings. In rheo-casting process the nucleation occurs on cooling slope with high rate in whole casting volume, so nuclei are numerous, resulting in very fine microstructure of nodular crystals. In this work the rheo-continuous process was carried out with a casting machine using 2 rollers of same size: diameter of 300 mm and width of 100 mm. The pouring temperature is near-liquidus. The microstructure obtained is fine (grain size < 40 μm), with nodular morphology. The mechanical properties of as-cast samples were high (the tensile strength is above 220 MPa).

Development of New Microalloyed Steel by Alloying with Tungsten

2014 ◽  
Vol 716-717 ◽  
pp. 48-51
Author(s):  
Jing Wei Zhao ◽  
Zheng Yi Jiang
Keyword(s):  
Impact Toughness ◽  
Fracture Strain ◽  
Microalloyed Steel ◽  
Cast Steel ◽  
Casting Process ◽  
Microalloyed Steels ◽  
Positive Role ◽  
Cast Steels ◽  
Impact Energies ◽  
The Impact

The effects of tungsten (W) addition on the microstructure, impact toughness and tensile properties of a microalloyed cast steel were systematically investigated. The results indicate that W alloying in microalloyed cast steel plays a positive role in inhibiting dendrite during casting process, and the yield strength, ultimate tensile strength and fracture strain can be simultaneously improved after W addition. Both microalloyed cast steels with and without W additions show very low impact energies, indicating W addition has no significant effect on the impact toughness. The present work provides a possibility to develop new W-containing microalloyed steels with improved mechanical properties.

scholarly journals Effect of Sm Doping on the Microstructure, Mechanical Properties and Shape Memory Effect of Cu-13.0Al-4.0Ni Alloy

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4007
Author(s):  
Qimeng Zhang ◽  
Bo Cui ◽  
Bin Sun ◽  
Xin Zhang ◽  
Zhizhong Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Strengthening Effect ◽  
Face Centered Cubic ◽  
Compressive Fracture ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Face Centered

The effects of rare earth element Sm on the microstructure, mechanical properties, and shape memory effect of the high temperature shape memory alloy, Cu-13.0Al-4.0Ni-xSm (x = 0, 0.2 and 0.5) (wt.%), are studied in this work. The results show that the Sm addition reduces the grain size of the Cu-13.0Al-4.0Ni alloy from millimeters to hundreds of microns. The microstructure of the Cu-13.0Al-4.0Ni-xSm alloys are composed of 18R and a face-centered cubic Sm-rich phase at room temperature. In addition, because the addition of the Sm element enhances the fine-grain strengthening effect, the mechanical properties and the shape memory effect of the Cu-13.0Al-4.0Ni alloy were greatly improved. When x = 0.5, the compressive fracture stress and the compressive fracture strain increased from 580 MPa, 10.5% to 1021 MPa, 14.8%, respectively. When the pre-strain is 10%, a reversible strain of 6.3% can be obtained for the Cu-13.0Al-4.0Ni-0.2Sm alloy.

scholarly journals Effect of Nano-Y2O3 Addition on Microstructure and Tensile Properties of High-Nb TiAl Alloy Prepared by Spark Plasma Sintering

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1048
Author(s):  
Yingchao Guo ◽  
Yongfeng Liang ◽  
Junpin Lin ◽  
Fei Yang
Keyword(s):  
Tensile Strength ◽  
Spark Plasma Sintering ◽  
Tial Alloy ◽  
Second Phase ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Y2o3 Addition ◽  
Powder Metallurgy Route

Nano-Y2O3 reinforced Ti-47.7Al-7.1Nb-(V, Cr) alloy was fabricated by a powder metallurgy route using spark plasma sintering (SPS), and the influence of nano-Y2O3 contents on the microstructure and mechanical properties were investigated systematically. The results revealed that the ultimate tensile strength and elongation of the alloy were 570 ± 28 MPa and 1.7 ± 0.6% at 800 °C, 460 ± 23 MPa and 6.1 ± 0.4% at 900 °C with no nano-Y2O3, 662 ± 24 MPa and 5.5 ± 0.5% at 800 °C, and 466 ± 25 MPa and 16.5 ± 0.8% at 900 °C with 0.05 at% nano-Y2O3 addition, respectively. Due to the fine-grain strengthening and the second-phase strengthening, both tensile strength and elongation of the high-Nb TiAl alloy were enhanced with the addition of nano-Y2O3.

scholarly journals Mechanical Properties of Al Matrix Composite Enhanced by In Situ Formed SiC, MgAl2O4, and MgO via Casting Process

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1767
Author(s):  
Yuhong Jiao ◽  
Jianfeng Zhu ◽  
Xuelin Li ◽  
Chunjie Shi ◽  
Bo Lu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Matrix Composite ◽  
Compression Strength ◽  
Casting Process ◽  
Al Alloy ◽  
Pyrolysis Process ◽  
Alloy Matrix ◽  
Al Matrix Composite ◽  
Al Matrix

Al matrix composite, reinforced with the in situ synthesized 3C–SiC, MgAl2O4, and MgO grains, was produced via the casting process using phenolic resin pyrolysis products in flash mode. The contents and microstructure of the composites’ fracture characteristics were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties were tested by universal testing machine. Owing to the strong propulsion formed in turbulent flow in the pyrolysis process, nano-ceramic grains were formed in the resin pyrolysis process and simultaneously were homogeneously scattered in the alloy matrix. Thermodynamic calculation supported that the gas products, as carbon and oxygen sources, had a different chemical activity on in situ growth. In addition, ceramic (3C–SiC, MgAl2O4, and MgO) grains have discrepant contents. Resin pyrolysis in the molten alloy decreased oxide slag but increased pores in the alloy matrix. Tensile strength (142.6 ± 3.5 MPa) had no change due to the cooperative action of increased pores and fine grains; the bending and compression strength was increasing under increased contents of ceramic grains; the maximum bending strength was 378.2 MPa in 1.5% resin-added samples; and the maximum compression strength was 299.4 MPa. Lath-shaped Si was the primary effect factor of mechanical properties. The failure mechanism was controlled by transcrystalline rupture mechanism. We explain that the effects of the ceramic grains formed in the hot process at the condition of the resin exist in mold or other accessory materials. Meanwhile, a novel ceramic-reinforced Al matrix was provided. The organic gas was an excellent source of carbon, nitrogen, and oxygen to in situ ceramic grains in Al alloy.

MICROSTRUCTURES AND DRY SLIDING WEAR RESISTANCE OF THE LASER CERAMICS COMPOSITE COATING ON PURE Ti

2012 ◽  
Vol 19 (03) ◽  
pp. 1250017 ◽  
Author(s):  
PENG LIU ◽  
YUANBIN ZHANG ◽  
HUI LUO ◽  
YUSHUANG HUO
Keyword(s):  
Wear Resistance ◽  
Composite Coating ◽  
Laser Cladding ◽  
Dry Sliding Wear ◽  
X Ray Diffraction ◽  
Phase Constituent ◽  
Fine Grain ◽  
Fine Grain Strengthening ◽  
Modification Technique ◽  
Surface Performance

In this study, Al–Ti–Co was used to improve the surface performance of pure Ti . Laser cladding is an important surface modification technique, which can be used to improve the surface performance of pure Ti . Laser cladding of the Al–Ti–Co + TiB2 pre-placed powders on pure Ti can form ceramics reinforced the composite coating, which improved the wear resistance of the substrate. Characteristics of the composite coating were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), microhardness and wear tests. And the laser-cladded coating can also have major dilution from the substrate. Due to the action of the fine grain strengthening and the phase constituent, the wear resistance and microhardness of pure Ti surface were greatly improved.

scholarly journals Roles of Lanthanum and Cerium in Grain Refinement of Steels during Solidification

Metals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 884 ◽  
Author(s):  
Yunping Ji ◽  
Ming-Xing Zhang ◽  
Huiping Ren
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Rare Earths ◽  
Heterogeneous Nucleation ◽  
The Past ◽  
Cast Steels ◽  
Steel Castings ◽  
Similarity And Difference

Refinement of as-cast structures is one of the most effective approaches to improve mechanical properties, formability, and surface quality of steel castings and ingots. In the past few decades, addition of rare earths (REs), lanthanum and cerium in particular, has been considered as a practical and effective method to refine the as-cast steels. However, previous reports contained inconsistent, sometime even contradictory, results. This review summaries the major published results on investigation of the roles of lanthanum or/and cerium in various steels, provides reviews on the similarity and difference of previous studies, and clarifies the inconsistent results. The proposed mechanisms of grain refinement by the addition of lanthanum or/and cerium are also reviewed. It is concluded that the grain refinement of steels by RE additions is attributed to either heterogeneous nucleation on the in-situ formed RE inclusions, a solute effect, or the combined effect of both. The models/theories for evaluation of heterogeneous nucleation potency and for solute effect on grain refinement of cast metals are also briefly summarized.

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