scholarly journals High-Temperature Mechanical Properties of 4.5%Al δ-TRIP Steel

2019 ◽  
Vol 9 (23) ◽  
pp. 5094
Author(s):  
Dayu Chen ◽  
Heng Cui ◽  
Rudong Wang
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
High Temperature ◽  
Grain Boundary ◽  
Trip Steel ◽  
Scanning Calorimetry ◽  
The Third ◽  
High Temperature Mechanical Properties ◽  
Brittle Zone ◽  
Austenite Grain Boundary

The high-temperature mechanical properties of a 4.5% Al-containing δ-transformation-induced plasticity (TRIP) steel were studied by using the Gleeble 3500 thermomechanical simulator. The zero ductility temperature (ZDT) and the zero strength temperature (ZST) were measured, and the brittle zones were divided. The phase transformation zone was determined by differential scanning calorimetry (DSC). The temperature of the phase transformation and the proportion of the phase were calculated by the Thermo-Calc software. The ZDT and the ZST of the 4.5% Al-containing δ-TRIP steel are 1355 and 1405 °C, respectively. The first brittle zone and the third brittle zone of the steel are 1300–1350 °C and 800–975 °C, respectively. The reason for the embrittlement of the third brittle zone of the 4.5% Al-containing δ-TRIP steel is that the α-ferrite formed at the austenite grain boundary causes the sample to crack along the grain boundary under stress. The ductility of the 4.5% Al-containing δ-TRIP steel decreases first and then increases with the increase of the α-ferrite. When the proportion of the α-ferrite reaches 37%, the reduction of area (RA) of the 4.5% Al-containing δ-TRIP steel is reduced to 44%. The 4.5% Al-containing δ-TRIP steel has good resistance to the high-temperature cracking.

Research on Hot Ductility Behavior of 800 MPa Grade Ultra High Strength Weathering Steel

2013 ◽  
Vol 815 ◽  
pp. 205-211
Author(s):  
Chao Bin Huang ◽  
Yan Zhu ◽  
Ru Yi Wu ◽  
Qing Shan Li ◽  
Mei Zhang ◽  
...  
Keyword(s):  
Grain Boundary ◽  
High Strength ◽  
Weathering Steel ◽  
Second Phase ◽  
Hot Ductility ◽  
The Third ◽  
Test Steel ◽  
Brittle Zone ◽  
Gleeble 3500 ◽  
Austenite Grain Boundary

The hot ductility behavior of test steel was investigated by Gleeble-3500 thermo-mechanical simulator through high temperature tensile test. The reduction in area (RA) and tensile strength (TS) were acquired to draw hot ductility curve and hot strength curve. SEM fractograph and microstructure of the tensile samples were analyzed. The results show that the third brittle zone of test steel is between 700°C and 800°C and the occurrence of the third brittle zone is mainly related to the formation of film-like ferrite along the prior austenite grain boundary and the precipitation of second phase. Moreover, the drop of hot ductility at 900°C is rooted in the reduction of grain boundary strength owing to the precipitation of sulfides. Therefore, it is advised that the straightening temperature of test steel should be kept over 900°C.

Characterization of grain boundary phases in Si3N4 sintered using Y-Si-Al-O-N additives

1990 ◽  
Vol 48 (4) ◽  
pp. 1070-1071
Author(s):  
C. Koehler ◽  
G. Thomas
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Elevated Temperatures ◽  
Secondary Phases ◽  
Amorphous Phases ◽  
High Temperature Mechanical Properties

The usefulness of silicon nitride as a high temperature ceramic can be limited by the presence of amorphous phases at the grain boundaries. Dense silicon nitride ceramics are produced using pressureless sintering of Si3N4 with Y-Si-Al-O-N additives. When these additives are left as a glassy phase at the grain boundaries and triple grain junctions, the mechanical properties at elevated temperatures are weakened due to these low viscous glasses. Post-sintering heat treatments and close compositional control can be effective in transforming the glass into crystalline phases at the grain boundaries thereby increasing the refractoriness.To optimize high temperature mechanical properties, processing must be controlled not only to fully crystallize the grain boundaries but also to avoid certain unstable secondary phases whose oxidation leads to large molar volume changes which causes possible cracking. Transmisssion electron microscopy and x-ray microanalysis (EDS) are significant methods to characterize the amorphous grain boundary pockets and to identify the crystalline grain boundary phases.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

AEM of reaction-bonded SiC

1992 ◽  
Vol 50 (1) ◽  
pp. 344-345
Author(s):  
K Das Chowdhury ◽  
R. W. Carpenter ◽  
W. Braue
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
High Temperature ◽  
Epitaxial Growth ◽  
Liquid Silicon ◽  
Structural Ceramic ◽  
Few Data

Research on reaction-bonded SiC (RBSiC) is aimed at developing a reliable structural ceramic with improved mechanical properties. The starting materials for RBSiC were Si,C and α-SiC powder. The formation of the complex microstructure of RBSiC involves (i) solution of carbon in liquid silicon, (ii) nucleation and epitaxial growth of secondary β-SiC on the original α-SiC grains followed by (iii) β>α-SiC phase transformation of newly formed SiC. Due to their coherent nature, epitaxial SiC/SiC interfaces are considered to be segregation-free and “strong” with respect to their effect on the mechanical properties of RBSiC. But the “weak” Si/SiC interface limits its use in high temperature situations. However, few data exist on the structure and chemistry of these interfaces. Microanalytical results obtained by parallel EELS and HREM imaging are reported here.

BERYLCO NICKEL ALLOY 440

Alloy Digest ◽  
1975 ◽  
Vol 24 (9) ◽  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Nickel Alloy ◽  
High Strength ◽  
Heat Treating ◽  
Electronic Components ◽  
High Temperature Mechanical Properties ◽  
Temperature Performance ◽  
Solution Treated ◽  
Complex Shapes

Abstract BERYLCO NICKEL ALLOY 440 is an age-hardenable nickel-beryllium-titanium alloy that offers high strength, excellent spring properties outstanding formability, good high-temperature mechanical properties, and resistance to corrosion and fatigue. Complex shapes can be produced in the solution-treated (soft) condition and then aged to a minimum tensile strength of 215,500 psi. It is used for mechanical and electrical/electronic components in the temperature range -320 to 800 F. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Ni-94. Producer or source: Kawecki Berylco Industries Inc.. Originally published September 1964, revised September 1975.

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