Optimalization of Tempering Temperature of 9CrNB Steel in Železiarne Podbrezová Steelworks

2017 ◽  
Vol 891 ◽  
pp. 137-142 ◽  
Author(s):  
Ľudovít Parilák ◽  
Pavel Bekeč ◽  
Lucia Domovcová ◽  
Pavol Beraxa ◽  
Milan Mojžiš ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Microstructural Analysis ◽  
Theoretical Studies ◽  
Secondary Phases ◽  
Tempering Temperature ◽  
Carbide Phases ◽  
Hot Rolled ◽  
Martensite Microstructure ◽  
Very High

This paper deals with the optimalization of tempering temperature of 9CrNB steel in Železiarne Podbrezová Steelworks, where hot-rolled tubes were produced with dimensions of 88.9 x 12.51 mm. Austenitising at 1070°C/12m/hr was carried out after rolling, and samples were subsequently tempered at 790°C, 760°C and 720°C/4m/hr. The results of testing the mechanical properties show that only tempering at 790°C fulfilled all of the mechanical properties requirements (Rp0,2, Rm, A5, HBW, KV2). The mechanical properties of grade P92 were used for comparison with 9CrNB mechanical properties, according to the relevant standard of STN EN 10216-2+A2. Yield strength requirements (Rp0,2) were also fulfilled in the temperature range from 100 to 600 °C. Microstructural analysis showed that tempering at 720°C, and also at 760°C does not lead to the complete tempering of martensite microstructure. We observed segregation of secondary phases at the grain boundary, but cementite films between individual laths did not coagulate to form carbide phases. By tempering at 790°C the intensity of formation of carbide phases, coagulation and growth of carbide phases is very high and leads to disintegration of laths. Despite satisfactory results, theoretical studies with respect to the selected chemical composition of 9CrNB steel show that to achieve sufficient dissolution of carbide or nitride phases (especially BN), it is necessary to use high temperature austenitization up to about 1200°C, followed by tempering below Ac1.

Performance Analysis of Fire-Resistant H-Beam Steel

2010 ◽  
Vol 163-167 ◽  
pp. 2949-2952
Author(s):  
Jian Qing Qian ◽  
Ji Ping Chen ◽  
Bao Qiao Wu ◽  
Jie Ca Wu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Chemical Composition ◽  
Room Temperature ◽  
High Temperature Strength ◽  
High Temperature Mechanical Properties ◽  
H Beam ◽  
Hot Rolled ◽  
Very High ◽  
Room Temperature Strength

The fire-resistant hot-rolled H-beam steel is the newly developed structure material. The development situation of the fire-resistant H-beam steel is briefly introduced. The chemical composition, microstructure, room temperature and high temperature mechanical properties and weldability of several batches of the developed domestic fire-resistant hot-rolled H-beam steels are comprehensively analyzed. The results show that the newly developed hot-rolled fire-resistant H-beam steel has very high room temperature strength, certain high temperature strength, good welding performance, but the toughness needs to be further improved. The performance of web and flange of H-beam steel has large gap.

Microstructural Design of Si3N4 Based Ceramics

1992 ◽  
Vol 287 ◽  
Author(s):  
M.J. Hoffmann ◽  
G. Petzow
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Microstructural Analysis ◽  
Coarse Grained ◽  
Boundary Phase ◽  
Microstructural Development ◽  
High Temperature Strength ◽  
Secondary Phases ◽  
The Matrix ◽  
High Degree

ABSTRACTParameters controlling the size and aspect ratio of elongated Si3N4 grains are discussed, based on the assumption that only pre-existing β-Si3N4 particles of the starting powder grow. Powder mixtures of α-rich and β-rich Si3N4 were prepared In order to study the microstructural development. The resulting microstructures were analyzed by quantitative microstructural analysis determining the distribution of the length and aspect ratio of the Si3N4 grains. Subsequently, the Influence of the sintering conditions on grain growth was analyzed In relation to mechanical properties. A high Weibull modulus and the non-catastrophic failure during thermal shock of coarse-grained materials Is attributed to an R-curve behaviour. Finally, the influence of sintering additives on the mechanical properties was studied. The Importance of phase relationships between the matrix and the grain boundary phase Is discussed for Si3N4 with Yb2O3 additives. It Is demonstrated that the oxygen content of Si3N4 powder must been taken Into account In order to devitrify defined secondary phases and to achieve a high degree of crystallization. A reduction in the amount of additives does not necessarily Improve the properties as high temperature strength and creep data Indicate.

Experimental Evaluation of Abradable Seal Performance at High Temperature

2008 ◽  
Author(s):  
A. Dadouche ◽  
M. J. Conlon ◽  
W. Dmochowski ◽  
B. Liko ◽  
J.-P. Bedard
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Gas Turbines ◽  
Operating Temperature ◽  
Microstructural Analysis ◽  
Operating Conditions ◽  
Effect Of Temperature ◽  
Gas Leakage ◽  
Series Of Experiments ◽  
Aero Engines

Abradable seals have been used in aero-engines and land-based gas turbines for more than three decades. They are applied to various sections of the engine in order to reduce gas leakage by optimizing the gap between rotating and stationary parts. This optimization represents a significant increase in efficiency and decrease in fuel consumption. Performance evaluation of any abradable seal includes measurement of its mechanical properties, abradability tests and (ultimately) tests in engines. The aim of this paper is to study the effect of temperature on the rub performance of abradable seals. A series of experiments has been carried out in order to evaluate a commercially available seal material at different operating conditions. The effect of operating temperature on contact force, abrasion scar appearance and blade wear is examined and analyzed. A microstructural analysis of the rub scar has also been performed.

Oxide Layers Mechanical Properties for Ni Base Alloys in HTR Environment

2008 ◽  
Vol 595-598 ◽  
pp. 501-509
Author(s):  
Damien Kaczorowski ◽  
Gouenou Girardin ◽  
S. Chamousset
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Heat Exchanger ◽  
Tensile Test ◽  
Oxide Layers ◽  
Intermediate Heat Exchanger ◽  
Nickel Base ◽  
Very High ◽  
High Temperature Gas

Nickel base alloys 617 and 230 are promising candidates for the Intermediate Heat eXchanger (IHX) of GenIV Very High Temperature gas cooled Reactors. The capability to maintain an oxide layer as an efficient barrier against corrosion under mechanical loading is investigated through SEM in situ tensile test. The mechanical properties of external oxide layers are so compared between the two alloys. Cracks and spallation are observed. Few differences could be observed between these two alloys when pre oxidized in impure helium.

Effect of Y on Microstructure and Mechanical Properties of Mg-6Al-1Zn-1.8Gd Magnesium Alloy

2014 ◽  
Vol 1035 ◽  
pp. 303-306
Author(s):  
Xiao Ya Chen ◽  
Quan An Li ◽  
Qing Zhang ◽  
Jun Chen ◽  
Hui Zhen Jiang
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Tensile Strength ◽  
High Temperature ◽  
Room Temperature ◽  
Tensile Tests ◽  
High Mechanical Property ◽  
Microstructure And Mechanical Properties ◽  
Micro Analysis ◽  
Very High

The microstructure and mechanical properties of Mg-6Al-1Zn-0.9Y-1.8Gd alloy have been studied by micro-analysis and tensile tests. The results showed that the alloy mainly consists of Mg matrix, Al2Y, Mg17Al12and Al2Gd. The best tensile strength of the alloy was 255 Mpa at room temperature, and the alloy still had the very high mechanical property at high temperature.

Effect of austenitizing and tempering on impact resistance of a hot rolled high strength steel

2021 ◽  
Vol 21 (1) ◽  
pp. 15-19
Author(s):  
Haider Mahdi Lieth ◽  
Ali Sabea Hammood
Keyword(s):  
Mechanical Properties ◽  
High Strength Steel ◽  
Impact Resistance ◽  
High Strength ◽  
Metallographic Analysis ◽  
Ballistic Performance ◽  
Tempering Temperature ◽  
Quenching Medium ◽  
Hot Rolled ◽  
The Impact

The aim of this study is to investigate the effect of heat treatments on the impact properties of hot rolled high strength steel and describes the effect of tempering temperature and quenching media on the microstructure, hardness, and impact resistance of plates. In the present study a high strength steel was austenitized at 900 °C with different quenching medium and followed by tempering at 300 °C, 500 °C. After thermal treatments, the values of Charpy impact resistance, hardness, and microscopic structure were evaluated from mechanical and metallographic analysis of metals respectively. The change of mechanical properties and microstructure of the metal with the existence of heat treatment with the ballistic performance of high-strength steel. Experimental results showed that tempering at 500 °C for 2 hours after water quenching medium it provides the best mechanical properties in conjunct on with an improved in microstructure.

High Temperature Aging and Corrosion Study on Alloy 617 and Alloy 230

2010 ◽  
Vol 133 (5) ◽  
Author(s):  
Kun Mo ◽  
Gianfranco Lovicu ◽  
Hsiao-Ming Tung ◽  
Xiang Chen ◽  
James F. Stubbins
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Temperature ◽  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Degradation Process ◽  
Grain Boundary Character Distribution ◽  
Alloy 617 ◽  
Production Of Hydrogen ◽  
Nuclear Systems

The very high temperature gas-cooled reactor (VHTR), with dual capacities of highly efficient electricity generation and thermochemical production of hydrogen, is considered as one of the most promising Gen-IV nuclear systems. The primary candidate materials for construction of the intermediate heat exchanger (IHX) for the VHTR are alloy 617 and alloy 230. To have a better understanding of the degradation process during high temperature long-term service and to provide practical data for the engineering design of the IHX, aging experiments were performed on alloy 617 and alloy 230 at 900°C and 1000°C. Mechanical properties (hardness and tensile strength) and microstructure were analyzed on post-aging samples after different aging periods (up to 3000 h). Both alloys attained increased hardness during the early stages of aging and dramatically soften after extended aging times. Microstructural analysis including transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and electron backscatter diffraction was carried out to investigate the microstructure evolution during aging. A carbide particle precipitation, growth, and maturing process was observed for both alloys, which corresponds to the changes of the materials’ mechanical properties. Few changes in grain boundary character distribution and grain size distribution were observed after aging. In addition, high temperature corrosion studies were performed at 900°C and 1000°C for both alloys. Alloy 230 exhibits much better corrosion resistance at elevated temperature compared with alloy 617.

Microstructure and Mechanical Properties of Steel Grade 14MoV6-3

2014 ◽  
Vol 782 ◽  
pp. 137-140 ◽  
Author(s):  
Lucia Domovcová ◽  
Pavol Beraxa ◽  
Milan Mojžiš ◽  
Michal Weiss ◽  
Martin Fujda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Steel Grade ◽  
Low Carbon ◽  
Stress Theory ◽  
Carbide Phases ◽  
Bainitic Microstructure ◽  
Industry Applications ◽  
Carbon Microalloyed ◽  
Hot Rolled

Steel grade 14MoV6-3 is a low-carbon microalloyed steel with addition of chromium and molybdenum. This medium-strength steel exhibits a ferritic-bainitic microstructure after the heat treatment. This grade is designed mainly for power industry applications, withstanding operating temperatures up to 580 °C; in Železiarne Podbrezová, this particular grade is used for production of hot rolled seamless boiler tubes. In this paper we present the basic chemical concept of 14MoV6-3 steel along with its mechanical properties after the heat treatment. Further, analysis of the final microstructure, carbide phases and precipitation of vanadium is being presented as well. For this purpose, the yield stress theory has been proposed along with predictive nomograms for selected ferritic-bainitic phases. According to the results of DTA analyses, necessary conditions for heat treatment after rolling have been proposed. Finally, CCT diagrams for required ferritic-bainitic structure are presented as well.

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