Effect of Niobium on Microstructure of X80 Grade Pipe Line Steels

2013 ◽  
Vol 368-370 ◽  
pp. 720-725
Author(s):  
Dong Jie Bao ◽  
Ji Ming Zhang ◽  
Qing Lin
Keyword(s):  
Retained Austenite ◽  
Lath Martensite ◽  
High Strength ◽  
Second Phase ◽  
Extraction Replica ◽  
Large Size ◽  
Transmission Electron ◽  
Second Phase Particles ◽  
Nb Content ◽  
Pipe Line

Microstructure of high strength pipeline steels containing different Nb contents was investigated using optical microscopy and transmission electron microscopy. Second phase particles were analyzed by extraction replica method. The results show that microstructure of the low Nb steel comprises granule bainite and the low bainite with a few of martensite-austenite (M-A) constituents. However, microstructure is consisted of acicular ferrite with M-A constituents in high Nb content steel. Moreover, M-A constituent is consisted of twinning martensite, lath martensite and retained austenite. In the low Nb steel precipitates are a large of square TiN particles. Second particles of high Nb content are mainly the large size duplex type (Nb,Ti)C and small NbC precipitates.

The Study on the Precipitation Behavior of the Second Phase Particles for Fine Grain and High Strength IF Steel

2012 ◽  
Vol 217-219 ◽  
pp. 411-414
Author(s):  
Hong Mei Zhang ◽  
Li Feng Qiao ◽  
Qin Bo Liu
Keyword(s):  
Grain Boundary ◽  
High Strength ◽  
Second Phase ◽  
If Steel ◽  
Precipitation Behavior ◽  
Extraction Replica ◽  
Carbon Extraction Replica ◽  
Fine Grain ◽  
Second Phase Particles ◽  
Precipitate Composition

The new type SFG HSS (super fine grain, high strength steel sheet) has been developed by adding solid-solution strengthening elements to conventional IF steel such as Si, Mn. The precipitation behavior of the second phase particles was observed and studied by a carbon extraction replica technique used transmission electron microscopy (TEM). The shape of the small second particles is similar to spherical and ellipse, the sizes of which are 10~30nm. It is seen that the particles are dispersed on the matrix. The precipitate composition of small particles is Nb (CN) and the precipitate composition of large particles is NbC examined by energy dispersive X-ray (EDX). It is noted that the yield strength is low as well as the tensile strength is high by the PFZ which is free of precipitate called precipitated free zone on the one side of the grain boundary. The results of microstructure shows that the second phase particles pinned on grain boundary not only can inhibit the grain growth, but also the grain can be fined.

Dependence of fracture toughness on multiscale second phase particles in high strength Al alloys

2003 ◽  
Vol 19 (7) ◽  
pp. 887-896 ◽  
Author(s):  
G. Liu ◽  
G.-J. Zhang ◽  
X.-D. Ding ◽  
J. Sun ◽  
K.-H. Chen
Keyword(s):  
Fracture Toughness ◽  
High Strength ◽  
Al Alloys ◽  
Second Phase ◽  
Second Phase Particles

scholarly journals Enhanced aging kinetics in Al-Mg-Si alloys by up-quenching

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Florian Schmid ◽  
Philip Dumitraschkewitz ◽  
Thomas Kremmer ◽  
Peter J. Uggowitzer ◽  
Ramona Tosone ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Treatment Time ◽  
Cluster Formation ◽  
High Strength ◽  
Second Phase ◽  
Second Phase Particles ◽  
Negative Effect ◽  
High Elongation ◽  
Aging Kinetics ◽  
Complex Parts

AbstractPrecipitation-hardened aluminium alloys typically obtain their strength by forming second-phase particles, which, however, often have a negative effect on formability. To enable both lightweight construction and forming of complex parts such as body panels, high strength and formability are required simultaneously. Cluster hardening is a promising approach to achieve this. Here, we show that short thermal spikes, denoted as up-quenching, increase aging kinetics, which we attribute to the repeated process of vacancies being formed at high temperatures and retained when cooled to lower temperatures. Combined with further heat treatment, the up-quenching process promotes rapid and extensive cluster formation in Al-Mg-Si alloys, which in turn generates significant strengthening at industrially relevant heat treatment time scales. The high elongation values also observed are attributed to reduced solute depleted zones along grain boundaries.

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.

scholarly journals The Mechanism of High-Strength Quenching-Partitioning-Tempering Martensitic Steel at Elevated Temperatures

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 94 ◽  
Author(s):  
Ke Zhang ◽  
Maoyuan Zhu ◽  
Bitong Lan ◽  
Ping Liu ◽  
Wei Li ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Elevated Temperatures ◽  
Martensitic Steel ◽  
Lath Martensite ◽  
Temperature Stability ◽  
High Strength ◽  
High Temperature Stability ◽  
High Deformation ◽  
Heat Treated ◽  
The Relationship

High-strength medium-carbon martensitic steel was heat treated through a quenching-partitioning-tempering (Q-P-T) treatment. Both the mechanism for improved ductility and the high temperature stability of austenite were investigated. The Q-P-T martensitic steel showed good products of strength and elongation (PSE) at various deformation temperatures ranging within 25–350 °C. The optimum PSE value (>57,738 MPa%) was achieved at 200 °C. The microstructure of the Q-P-T steel is constituted of laths martensite with dislocations, retained austenite located within lath martensite and small niobium carbides (NbC), and/or transitional ε-carbides that precipitated in the lath martensite. The good ductility can be mainly attributed to the laminar-like austenite that remained within the lath-martensite. The austenite can effectively enhance ductility through the effect of dislocation absorption by the retained austenite and through transformation-induced plasticity. The relationship between the microstructures and mechanical properties was investigated at high deformation temperatures.

Effect of Nb Addition on the Structural and Mechanical Properties of Cu46Zr42Al7Y5 Bulk Metallic Glass

2011 ◽  
Vol 675-677 ◽  
pp. 201-204
Author(s):  
Y.L. Du ◽  
H.W. Xu ◽  
J.L. Cheng ◽  
Guang Chen
Keyword(s):  
Mechanical Properties ◽  
Amorphous State ◽  
Differential Scanning Calorimetric ◽  
Second Phase ◽  
Glass Forming ◽  
Copper Mold Casting ◽  
Mold Casting ◽  
Second Phase Particles ◽  
Nb Content ◽  
Nb Addition

In this work, the Cu46Zr42-xAl7Y5Nbx alloys with different Nb contents were prepared by water-cooled copper mold casting. The effects of Nb addition on the structural and mechanical properties were studied. It was found that the structure remains in amorphous state at low Nb concentration (x =1, 2). However, some crystalline phases appear in the high Nb content alloy (x > 2), showing a composite structure, that is, the second phase particles dispersed in an amorphous matrix. The effects of Nb on the glass-forming ability of Cu46Zr42Al7Y5 were studied by differential scanning calorimetric (DSC). The compressive mechanical properties of Cu46Zr42-xAl7Y5Nbx alloys were studied. It was found that the compressive strength can be improved by introducing Nb. However, the ductile of the alloys were not improved by the introduction of Nb.

Texture, Microstructure and Second-Phase Particles in a Ti+P Interstitial Free (IF) Steel

2005 ◽  
Vol 495-497 ◽  
pp. 423-428 ◽  
Author(s):  
Q.W. Jiang ◽  
E.B. Zhao ◽  
J.G. Zhang ◽  
Y. Chen ◽  
Gang Wang ◽  
...  
Keyword(s):  
Cold Rolling ◽  
High Strength ◽  
Strain Ratio ◽  
Warm Rolling ◽  
Second Phase ◽  
Rolled Sheet ◽  
Interstitial Free ◽  
If Steel ◽  
Plastic Strain Ratio ◽  
Second Phase Particles

The microstructure of Ti+P IF steel were studied after warm rolling, cold rolling and recrystallization using X-Ray, TEM and SEM. The results show that the characteristics of warm rolled sheet are the same as that of the cold rolled, but the texture displays different characteristics in the subsequent cold rolling and recrystallization because of the numerous second-phase particles. In this work, a Ti+P IF steel sheet with high strength and plastic strain ratio was obtained.

Characteristics of Deposition Precipitation Process in Production of High Strength and Low Carbon Steel in FTSR

2014 ◽  
Vol 886 ◽  
pp. 128-131
Author(s):  
Zhuo Fei Song ◽  
Shan Shan Feng ◽  
Yun Li Feng
Keyword(s):  
Solid State ◽  
Low Carbon Steel ◽  
High Strength ◽  
Dynamical Analysis ◽  
Precipitation Process ◽  
Second Phase ◽  
Low Carbon ◽  
Second Phase Particles ◽  
Thermodynamics And Dynamics ◽  
Hot Rolled

Precipitation characteristics of second phase in HSLC steel produced by FTSR technology have been researched by TEM and EDS in this article. And preliminary research of precipitation conditions of second phase particles in thermodynamics and dynamics have been took. The results indicate that: there’re second phase particles precipitated dispersively in hot rolled HSLC steels by FTSR technology. These particles mainly contain particles of Al2O3、MnS and AlN. Thermo dynamical analysis declares that most of the Al2O3 and all of the MnS、 AlN particles are precipitated in solid state. That’s why the precipitation process is slowed down by the diffusion velocity of the elements in solid, and thinner particles are precipitated while the material is in solid state than in liquid state.

Transmission electron microscopy observation of second-phase particles in β–Si3N4 grains

1999 ◽  
Vol 14 (7) ◽  
pp. 2959-2965 ◽  
Author(s):  
Naoto Hirosaki ◽  
Tomohiro Saito ◽  
Fumio Munakata ◽  
Yoshio Akimune ◽  
Yuichi Ikuhara
Keyword(s):  
Electron Microscopy ◽  
Silicon Nitride ◽  
Heat Treating ◽  
High Resolution Electron Microscopy ◽  
Second Phase ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Second Phase Particles ◽  
Coarse Grains ◽  
Sintered Silicon

Silicon nitride was fabricated by adding Y2O3 and Nd2O3 as sintering additives, sintering for 8 h at 1900 °C, and heat treating for 4 h at 2200 °C to enhance grain growth. The microstructure was investigated by scanning electron microscopy, high-resolution electron microscopy, energy dispersive x-ray spectroscopy (EDS), and electron microdiffraction. This material had a duplex microstructure composed of many fine grains and a few coarse grains. In β–Si3N4 grains, second-phase particles with the composition of liquid phase, Y–Nd–Si–O or Y–Nd–Si–O–N, in the size of 10–30 nm were observed. EDS spectra and microdiffraction patterns revealed that those were amorphous or crystalline particles of Y–Nd–apatite, (Y,Nd)10Si6O24N2. These particles were presumably formed during cooling by the precipitation of Y–Nd–Si–O–N, which was trapped in the β–Si3N4 grains as solid solution or trapped liquid. The results suggest that attention should be paid to the trace amounts of trapped elements in β–Si3N4 grains in trying to improve the thermal conductivity of sintered silicon nitride.

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