scholarly journals Research on Formation Conditions of the Ultrafine-Grained Structure of the Cylindrical Parts Manufactured by Power Spinning Based on Small Strains

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1891 ◽  
Author(s):  
Gangfeng Xiao ◽  
Qinxiang Xia ◽  
Xiuquan Cheng ◽  
Weiping Chen
Keyword(s):  
Dislocation Density ◽  
Lath Martensite ◽  
Recrystallization Annealing ◽  
Second Phase ◽  
Power Spinning ◽  
Small Strains ◽  
Ultrafine Grained ◽  
Cylindrical Parts ◽  
Formation Conditions ◽  
Storage Energy

Two different methods, power spinning and annealing (PSA), quenching and power spinning followed by annealing (QPSA), for manufacturing the cylindrical parts with ultrafine-grained (UFG) structure were reviewed, the dislocation density and microstructural evolution during the two different processes of PSA and QPSA were further studied. The results show that the required strains for obtaining the UFG structure by power spinning is only 0.92 when the initial microstructure of the material is in the phase of lath martensite. The dislocation density and storage energy are increased to 10 times that of the blank after quenching and power spinning and decreased to the level of the blank after recrystallization annealing. Microstructures with fine grain size after quenching, storage energy of 1.8 × 105 kJ/m3 obtained after power spinning and second phase particle with nano-scale precipitated during annealing are the necessary formation conditions for manufacturing the cylindrical parts with UFG structure based on small strains. Compared with the original tubular blank, the mechanical properties of the spun parts with UFG structure improves significantly. The tensile strength and hardness of the spun parts manufactured by QPSA method is 815 MPa and 305 HV, respectively, and the elongation is 17.5%.

Microstructure and mechanical properties of 15-5 PH stainless steel under different aging temperature

2021 ◽  
Vol 118 (6) ◽  
pp. 601
Author(s):  
Chunhui Jin ◽  
Honglin Zhou ◽  
Yuan Lai ◽  
Bei Li ◽  
Kewei Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
Aging Temperature ◽  
Electron Backscatter Diffraction ◽  
Lath Martensite ◽  
Optical Microscope ◽  
Second Phase ◽  
Strengthening Mechanisms ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron

The influence of aging temperature on microstructure and mechanical properties of Cr15Ni5 precipitation hardening stainless steel (15-5 PH stainless steel) were investigated at aging temperature range of 440–610 °C. The tensile properties at ambient temperature of the 15-5 PH stainless steel processed by different aging temperatures were tested, and the microstructural features were further analyzed utilizing optical microscope (OM), transmission electron microscope (TEM), electron backscatter diffraction (EBSD) as well as X-ray diffraction (XRD), respectively. Results indicated the strength of the 15-5 PH stainless steel was firstly decreased with increment of aging temperature from 440 to 540 °C, and then increased with the increment of aging temperature from 540 to 610 °C. The strength and ductility were well matched at aging temperature 470 °C, and the yield strength, tensile strength as well as elongation were determined to be 1170 MPa, 1240 MPa and 24%, respectively. The microstructures concerning to different aging temperatures were overall confirmed to be lath martensite. The strengthening mechanisms induced by dislocation density and the second phase precipitation of Cu-enriched metallic compound under different aging temperatures were determined to be the predominant strengthening mechanisms controlling the variation trend of mechanical properties corresponding to different aging temperatures with respect to 15-5 PH stainless steel.

The Influence of Mobile Dislocation Density on the Fracture Toughness of B2-Based Ni-Fe-Al Alloys

1994 ◽  
Vol 350 ◽  
Author(s):  
A. Misra ◽  
R. D. Noebe ◽  
R. Gibala
Keyword(s):  
Fracture Toughness ◽  
Dislocation Density ◽  
Tensile Ductility ◽  
Growth Direction ◽  
Mobile Dislocation ◽  
Second Phase ◽  
Mobile Dislocation Density ◽  
Dislocation Generation ◽  
Multiphase Materials ◽  
Β Phase

AbstractThe deformation and fracture behaviors of two directionally solidified multi-phase Ni-Fe-Al ordered alloys were investigated. One alloy consisted of continuous β+γ lamellae with fine γ precipitates within the γ phase. The NiAl-based β phase of this alloy exhibited <100> slip even when deformed parallel to the [001] growth direction. This material exhibited an initiation fracture toughness of ∼ 30 MPa √m and tensile ductility of 10%. The second alloy consisted of aligned but discontinuous γ lamellae within a continuous β phase. Again, the γ phase contained γ precipitates, but unlike the previous alloy, the β phase also contained a fine dispersion of bcc precipitates due to spinodal decomposition. The β phase of this alloy deformed by <111> slip. This four-phase alloy exhibited a fracture toughness of ∼ 21 MPa √m and tensile ductility of 2%. Observations of the plastic zone in both alloys indicated significant plasticity in the β phase due to easy slip transfer from the ductile second phase. The enhanced fracture resistance of these multiphase materials compared to single phase β alloys is attributed in large part to intrinsic toughening of the β phase by an increased mobile dislocation density due to efficient dislocation generation from the β/γ interfaces.

Processing of Ultrafine-Grained Cu-Fe-Cr Composite by Equal Channel Angular Pressing

2006 ◽  
Vol 503-504 ◽  
pp. 71-76
Author(s):  
K.H. Joo ◽  
K.I. Chang ◽  
Hyoung Seop Kim ◽  
Sun Ig Hong
Keyword(s):  
Equal Channel Angular Pressing ◽  
Reverse Direction ◽  
Microstructural Development ◽  
Second Phase ◽  
Morphological Development ◽  
Shear Direction ◽  
Pronounced Change ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
First Pass

In this study, equal channel angular pressing was carried out on Cu-Fe-Cr composites at room temperature. The microstructure and hardness of Cu-Fe-Cr pressed using different ECAP routes were investigated. All Cu-Fe-Cr specimens showed ultrafine-grained microstructures with the shape and distribution of Fe-Cr phase dependent on the processing routes. As the number of pressing increased by route A, the initial denfrite of Fe-Cr phase were elongated along the shear direction and developed into filaments. On the other hand, as the number of pressing increased by route Bc, the initial dendrite became finer by fragmentation with no pronounced change of the shape. In route C, the shearing of the second phase in the first pass can be reversed by the shearing in the reverse direction in the second pass and the morphological change of Fe-cr particles is minimal. The hardness increased more rapidly in route Bc and route C than in route A. In ECAPed Cu-Fe-Cr, the spacing between Fe-Cr filaments did not decrease appreciably with strain unlike the cold-drawn Cu-Fe-Cr in which the spacing between Fe-Cr filaments decreases rapidly with strain. The higher strength in route C can be associated with the sub-divided microstructure resulting from the activation of various slip systems enhanced by the presence of larger strong particles. This result suggests that the microstructural development in Cu matrix is more important in strengthening than the morphological development of Fe-Cr phase in ECAPed Cu-Fe-Cr.

Ultrafine-Grained Steel Produced by Warm Rolling and Annealing of Lath Martensite

2010 ◽  
Vol 667-669 ◽  
pp. 863-866
Author(s):  
Xin Zhao ◽  
Xiao Ling Yang
Keyword(s):  
Lath Martensite ◽  
Tensile Tests ◽  
Total Elongation ◽  
Optical Microscope ◽  
Warm Rolling ◽  
Steel Plates ◽  
Transmission Electron ◽  
Hardness Tests ◽  
Ultrafine Grained ◽  
Ultrafine Grained Steel

Steel plates with lath martensite microstructure were rolled up to 68% reduction at 673 K and then annealed at 473-973 K. The microstructure evolution was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that ultrafine grains + nano-carbides are obtained in the steel plates. The specimen annealed at 823 K has a good combination of strength and ductility. The tensile strength and total elongation are 1028 MPa and 7.2%, respectively. And the hardness is 338 Hv.

scholarly journals Evolution of microstructure and hardness during artificial aging of an ultrafine-grained Al-Zn-Mg-Zr alloy processed by high pressure torsion

2020 ◽  
Vol 55 (35) ◽  
pp. 16791-16805
Author(s):  
Jenő Gubicza ◽  
Moustafa El-Tahawy ◽  
János L. Lábár ◽  
Elena V. Bobruk ◽  
Maxim Yu Murashkin ◽  
...  
Keyword(s):  
High Pressure ◽  
Dislocation Density ◽  
Grain Boundaries ◽  
Artificial Aging ◽  
High Pressure Torsion ◽  
Secondary Phase ◽  
Aging Effect ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Evolution Of Microstructure

Abstract An ultrafine-grained (UFG) Al-4.8%Zn-1.2%Mg-0.14%Zr (wt%) alloy was processed by high pressure torsion (HPT) technique and then aged at 120 and 170 °C for 2 h. The changes in the microstructure due to this artificial aging were studied by X-ray diffraction and transmission electron microscopy. It was found that the HPT-processed alloy has a small grain size of about 200 nm and a high dislocation density of about 8 × 1014 m−2. The majority of precipitates after HPT are Guinier–Preston (GP) zones with a size of ~ 2 nm, and only a few large particles were formed at the grain boundaries. Annealing at 120 and 170 °C for 2 h resulted in the formation of stable MgZn2 precipitates from a part of the GP zones. It was found that for the higher temperature the fraction of the MgZn2 phase was larger and the dislocation density in the Al matrix was lower. The changes in the precipitates and the dislocation density due to aging were correlated to the hardness evolution. It was found that the majority of hardness reduction during aging was caused by the annihilation of dislocations and some grain growth at 170 °C. The aging effect on the microstructure and the hardness of the HPT-processed specimen was compared to that observed for the UFG sample processed by equal-channel angular pressing. It was revealed that in the HPT sample less secondary phase particles formed in the grain boundaries, and the higher amount of precipitates in the grain interiors resulted in a higher hardness even after aging.

Finite element simulation of the one-pass inner spinning process of curved generatrix cone cylindrical parts and analysis of their microstructure

2020 ◽  
Vol 234 (9) ◽  
pp. 1786-1796
Author(s):  
Zengliang Hao ◽  
Junting Luo ◽  
Yongbo Jin ◽  
Jinheng Liu ◽  
Zhenjie Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Finite Element ◽  
Mechanical Performance ◽  
Phase Distribution ◽  
Fracture Morphology ◽  
Second Phase ◽  
Finite Element Software ◽  
Spinning Process ◽  
Cylindrical Parts ◽  
Thin Walled

A one-pass annealing–internal spinning is proposed to form a conical thin-walled shell with large curved generatrix. The structure of the blank used is designed based on product-size requirements. ABAQUS finite element software is used to simulate the internal spinning process of a conical thin-walled shell with large curved generatrix under small-end (process 1) and large-end (process 2) rotations. The microstructure of the products is subsequently analyzed. Results show that the spinning pressure of the skin part under process 1 is relatively stable, and that the strain and residual stress distribution are uniform, and the hardness and the mechanical performance is improved. The products of the two processes have an obvious circumferential fiber structure. The second phase grain size in the fracture morphology of the product formed under the process 1 is uniform, and its size is in the range of 2–6 µm. Whereas, the second phase distribution of the product formed under the process 2 is not uniform, the fine second phase grain size is in 1–2 µm, and the coarse second phase grain size is in 5–8 µm.

Formation of Ultrafine Grained Ferrite by Warm Deformation of Tempered Lath Martensite in Low Alloy Steels

2007 ◽  
Vol 558-559 ◽  
pp. 557-562 ◽  
Author(s):  
Behrang Poorganji ◽  
Takuto Yamaguchi ◽  
Tadashi Maki ◽  
G. Miyamoto ◽  
Tadashi Furuhara
Keyword(s):  
Grain Size ◽  
Carbon Content ◽  
Volume Fraction ◽  
Boundary Migration ◽  
Lath Martensite ◽  
Second Phase ◽  
Low Alloy Steels ◽  
Warm Deformation ◽  
Alloy Steels ◽  
Block Width

Microstructure change during warm deformation of tempered lath martensite in Fe-2mass%Mn-C alloys with different carbon contents in the range between 0.1 and 0.8mass%C was investigated. Specimens of the alloys after being quenched and tempered at 923K for 0.3ks were compressed by 50% with a strain rate varying from 10-3 to 10-4s-1 at 923K. EBSD analysis of the deformed microstructures has revealed that fine equiaxed ferrite (α) grains surrounded by high-angle boundaries are formed by dynamic recrystallization (DRX). As carbon content increases, the DRX α grain size decreases. This could be attributed to the change in volume fraction of the cementite (θ) phase as boundary dragging particles. The sub-micron θ particles can suppress the coarsening of the DRX α grains by exerting a pinning effect on grain boundary migration. Furthermore, the fraction of recrystallized region increases by increasing carbon content, presumably due to a decrease in the martensite block width as an initial α grain size and a larger volume fraction of hard second phase (θ) particles. Both of these should increase inhomogeneous plastic deformation which promotes the recrystallization. It seems that continuous DRX is responsible for the formation of ultrafine α grains in the tempered lath martensite.

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