Ultra-fine grain size and exceptionally high strength in dilute Mg–Ca alloys achieved by conventional one-step extrusion

2019 ◽  
Vol 237 ◽  
pp. 65-68 ◽  
Author(s):  
Hucheng Pan ◽  
Changlin Yang ◽  
Yantao Yang ◽  
Yongqiang Dai ◽  
Dengshan Zhou ◽  
...  
Keyword(s):  
Grain Size ◽  
High Strength ◽  
Fine Grain ◽  
One Step

Improvement of Strength and Ductility by Combining Static Recrystallization and Unique Heat Treatment in Co-20Cr-15W-10Ni Alloy for Stent Application

2021 ◽  
Vol 1016 ◽  
pp. 1503-1509
Author(s):  
Kosuke Ueki ◽  
Soh Yanagihara ◽  
Kyosuke Ueda ◽  
Masaaki Nakai ◽  
Takayoshi Nakano ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Static Recrystallization ◽  
High Strength ◽  
Small Variation ◽  
Grain Structure ◽  
Fine Grain ◽  
High Temperature Short Time ◽  
Average Grain Size ◽  
Strength And Ductility

The Co-20Cr-15W-10Ni (CCWN, mass%) alloy has excellent corrosion resistance and strength-ductility balance and is applied in almost all balloon-expandable stent platforms. To further reduce the invasiveness of stent placement, it is necessary to reduce the diameter of the stent. That is, both high strength and high ductility should be achieved while maintaining a low yield stress. In our previous studies, it was discovered that low-temperature heat-treatment (LTHT) at 873 K improves the elongation of the CCWN alloy. In this study, we focused on the grain refinement by swaging and static recrystallization to improve the strength of the alloy. The as-swaged alloy was recrystallized at 1373–1473 K for 100–300 s, followed by LTHT. A fine grain structure with an average grain size of 3–17 μm was obtained by static recrystallization. The η-phase (M12X-M6X type precipitates, M: metallic elements, X: C and/or N) formed during the recrystallization at 1373–1448 K. The alloys recrystallized at 1448 and 1473 K had a homogeneous structure with a small variation in the grain size. On the other hand, the alloys recrystallized at 1373 and 1423 K had an inhomogeneous structure in which fine and coarse grains were mixed. Both the strength and ductility of the CCWN alloy were improved by combining high-temperature short-time recrystallization and LTHT.

Research and Development of U68CuCr Rail Steel

2012 ◽  
Vol 482-484 ◽  
pp. 989-995
Author(s):  
Yu Ji ◽  
Zhong Min Yang ◽  
Min Zhu ◽  
Wan Ling Zhang
Keyword(s):  
Grain Size ◽  
Chemical Composition ◽  
Research And Development ◽  
Production Process ◽  
Rail Steel ◽  
High Strength ◽  
Immersion Test ◽  
Corrosion Resistant ◽  
Fine Grain ◽  
Hot Rolled

According to characteristics of the marine environment corrosion, 980MPa steel were developed. After design rational chemical composition and production process, the full section hot-rolled corrosion-resistant sorbite rail steel were successfully developed. this kind of steel has fine grain size, high strength and perfect toughness. Dry-wet immersion test showed that lift of this rail is 70% longer than U75V.

Optimization of the Post Heat Treatment of Additively Manufactured IN718

2021 ◽  
Author(s):  
Alber Sadek
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
High Performance ◽  
High Strength ◽  
Fatigue Properties ◽  
Primary Carbide ◽  
Soaking Time ◽  
Fine Grain ◽  
Annealing Cycle ◽  
Treatment Procedures

Abstract IN718 has good fabricability, high strength at elevated temperature, and corrosion resistance, and it is widely deployed in many aerospace and other high-performance applications. With the molten pool rapid solidification during laser powder bed fusion (L-PBF), the resulting microstructure is anisotropic and inhibits macro-segregation. The as-built condition usually exhibits lower mechanical properties. Four different heat treatment procedures were designed and tested to study the effect of different heat treatment parameters on the type of precipitates and grain size. The investigated heat treatment procedures showed the formation of equiaxed grain size and a significant amount of γ' and γ" particles at the grain boundary in addition to primary carbide types (MC). Three types of microstructure characteristics and grain size were achieved. Coarse grain size suitable for creep application was achieved by increasing the soaking time at the aging cycle. The formation of serrated grain boundaries suitable for good fatigue and creep properties was achieved by decreasing the stress relief cycle's soaking time and temperature. Fine-grain size, which is preferable for fatigue properties, was achieved by decreasing the soaking time at the solution annealing cycle.

Grain Size Effect on Low Cycle Fatigue Behavior of High Strength Structural Materials

2016 ◽  
Vol 258 ◽  
pp. 269-272
Author(s):  
Ryuichiro Ebara
Keyword(s):  
Grain Size ◽  
Fatigue Strength ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
High Strength ◽  
Grain Size Effect ◽  
Cycle Fatigue ◽  
Fracture Surfaces ◽  
Fine Grain ◽  
Number Of Cycles

This paper presents grain size effect on low cycle fatigue behavior of high strength maraging steel with gain size of 20,60 and 100μm and Ti-6Al-4V alloy with grain size of 0.5,1.4 and 5.1μm. Low cycle fatigue strength of the maraging steel depends on grain size in number of cycles up to 103.The smaller the grain size, the higher the low cycle fatigue strength was. Quasci-cleavage fracture surfaces were predominant for material with grain size of 20μm,while intergranular fracture surfaces were predominant for materials with larger grain size in number of cycles lower than 60. Striation was predominant for all tested materials in number of cycles higher than 60.Low cycle fatigue strength of Ti-6Al-4V alloy also depends on grain size in number of cycles up to 104. Grain size dependent transgranular fracture surfaces were predominant for materials with ultra-fine grain size of 0.5μm and fine grain size of 1.4μm.

Fatigue of Ultra-Fine Grained α-Brass

2014 ◽  
Vol 891-892 ◽  
pp. 1125-1130
Author(s):  
Yoshikazu Nakai ◽  
Takuto Imanaka ◽  
Daiki Shiozawa
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Severe Plastic Deformation ◽  
Fatigue Limit ◽  
High Strength ◽  
Angular Pressing ◽  
Fine Grain ◽  
Proof Strength

Combined methods to obtain ultra-fine grain (UFG) α-brass samples are proposed. Severe plastic deformation followed by recrystallization was conducted, where multiple rolling and equal channel angular pressing (ECAP) were employed. Recrystallization was accomplished by heat-treatment after the severe plastic deformation, and the grain size after the severe plastic deformation was decreased. By multiple rolling, plates with thickness of 0.1 mm and grain size of 1.0 μm were obtained. By ECAP process, square bar with cross-section of 6 mm × 6 mm and minimum grain size of 4.1 μm was obtained. The 0.2 % proof strength, ultimate tensile strength, and fatigue limit were increased with the value of inverse square root of grain size (Hall-Petch relationship). Then, the 0.2 % proof strength of UFG brass was tenfold, the ultimate tensile strength and the fatigue limit were two fold increases from the conventional α-brass. Because of the high strength, the scatter of fatigue strength of UFG brass was large, which reflects the sensitivity to defects in material.

Correlation Between Microstructure and Yield Strength in Low-Carbon High-Strength Microalloyed Steels

2006 ◽  
Author(s):  
K. Poorhaydari ◽  
B. M. Patchett ◽  
D. G. Ivey
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
High Strength ◽  
Microalloyed Steels ◽  
Low Carbon ◽  
Microscopy Imaging ◽  
Relative Contribution ◽  
Fine Grain ◽  
Structural Applications ◽  
Carbon Microalloyed

Microalloyed pipeline and structural steels are currently graded according to their yield strength. In this work, different microstructural factors that affect the yield strength of the steels are assessed and their contributions to the strength are estimated for several low-carbon microalloyed steels, used in pipeline or structural applications. Emphasis is placed on the relative contribution of grain/sub-grain size, precipitate distribution and dislocation density. Accurate grain/sub-grain size measurements were only possible through electron microscopy imaging. It was found that the increased strength is mainly due to the formation of bainitic structures with fine grain/sub-grain sizes. The contribution from other strengthening sources such as precipitates, dislocations and atoms in solid solution is limited and does not vary much among the several grades examined here. The variation in hardness among the fine-grained heat-affected zone samples (heat input range 0.5–2.5 kJ/mm) of one of the steels was also explained based on the microstructural changes.

Determination of Mechanical Properties on Aluminium with 5% Copper Powder Metallurgy Route Compacts through Equal Channel Angular Pressing

2015 ◽  
Vol 813-814 ◽  
pp. 161-165
Author(s):  
M. Sadhasivam ◽  
T. Pravin ◽  
S. Raghuraman
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Equal Channel Angular Pressing ◽  
High Strength ◽  
Angular Pressing ◽  
Fine Grain ◽  
Plastic Deformation Process

The need for super-plasticity and high strength leads to the development of Severe Plastic Deformation technique. The strength of the material is directly dependent upon the grain size of the material. So, there is a need for producing Ultra-Fine Grain microstructure (UFG). UFG material is the material with very small grain size in the range of sub-micrometre. Application of severe plastic deformation, imparts extremely high strain. Equal channel angular pressing (ECAP) is a severe plastic deformation process in which the metal specimen is pressed through an angular channel of equal cross section. The material is subjected to shear deformation and strain is imparted in the specimen. Geometric parameters such as channel angle and corner angle play a major role in grain refinement. Aluminium (Al) specimens are subjected to undergo severe plastic deformation. Since, the strength of Al is not high, other materials are added in order to enhance its mechanical properties by matrix work hardening. Copper (Cu) along with Al shows increase in its strength and also in hardness. An attempt is made with Aluminium and copper, blended in the ratio 95:5 by weight with the main objective to study the Tensile strength, Hardness and Percentage Elongation properties of the specimen.

Toughness of Advanced High Strength Bainitic Steels

2010 ◽  
Vol 638-642 ◽  
pp. 118-123 ◽  
Author(s):  
Francisca García Caballero ◽  
J. Chao ◽  
J. Cornide ◽  
Carlos García-Mateo ◽  
Maria Jesus Santofimia ◽  
...  
Keyword(s):  
Grain Size ◽  
Room Temperature ◽  
Bainitic Ferrite ◽  
High Strength ◽  
Total Elongation ◽  
Martensitic Steels ◽  
Transformation Theory ◽  
Fine Grain ◽  
Bainitic Steels ◽  
Strength And Toughness

Carbide free bainite has achieved the highest strength and toughness combinations to date for bainitic steels in as-rolled conditions. By alloying designing and with the help of phase transformation theory, it was possible to improve simultaneously the strength and toughness because of the ultra-fine grain size of the bainitic ferrite plates. Ultimate tensile strengths ranging from 1600 MPa to 1800 MPa were achieved while keeping a total elongation higher than 10 %. Their toughness at room temperature matches tempered martensitic steels, known to be the best-in-class regarding this property. However, it has been observed that the presence of coalesced bainite leads to a dramatic deterioration in toughness in these novel high strength bainitic steels.

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