Increasing the service life of pellet car grate bars made of 40Х24Н12СЛ steel

2021 ◽  
Vol 77 (10) ◽  
pp. 1066-1075
Author(s):  
D. I. Ivanov ◽  
A. A. Kozhukhov
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Practical Significance ◽  
Minimum Length ◽  
Network Growth ◽  
Entire Volume ◽  
Structure Defects ◽  
Carbide Network ◽  
Globular Form ◽  
Experimental Technology

Intercrystallite corrosion (ICC) is the main reason to decrease service life of pellet car grate bars made of steel 40Х24Н12СЛ. In the process of the study of microstructure of pellet car grate bars manufactured according to GOST 977–88, the structure defects were established that increase the tendency to ICC. To prevent the ICC of the bars, a mode of heat treatment was elaborated, consisting of two basic operations: air hardening with preliminary exposure within 80 minutes at the temperature 1100 °С, followed by tempering within 150 minutes at the temperature 900 °С. The study of the structure of the pilot grate bar showed that the selected mode of the hardening enables to dissolve the carbide network in the structure of the detail and crash large carbides, and the subsequent tempering contributes to the growth of the carbide phase in the entire volume of metal, partially remaining in the structure after hardening. It was shown that the proposed mode of the heat treatment contributes to bringing the structure of the metal to a more “equilibrium” state, which will allow to exclude the formation of large carbides and carbide network, growth and coagulation along the grain boundary. Results of tests of a pilot batch of grate bars installed at an industrial induration machine with a working area of 768 m2 and operating temperature of 20–1310°С presented. It was established that the elaborated technology ensures absence of casting defects in the grate bars – cracks and warping, inclination of the grate bars to ICC, increased by 23.13% heat resistance compared to the reference grate bars of foreign supply due to the globular form of carbide secretions with a minimum length of borders along which the metal matrix is depleted by chrome. Industrial testing of the grate bars manufactured under the experimental technology has proved the practical significance and applicability of the performed research.

Viability of turbine blade material with a long service life

2019 ◽  
pp. 28-35
Author(s):  
O. B. Berdnik ◽  
I. N. Tsareva ◽  
M. K. Chegurov
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Yield Strength ◽  
Mechanical Characteristics ◽  
Operating Time ◽  
Structural Features ◽  
Operating Conditions ◽  
Standard Methods ◽  
Experimental Values ◽  
Plasticity Coefficient

This article deals with structural features and characteristic changes that affect the mechanical characteristics after different service life in real conditions using the example of the blades of the 4th stage of turbine GTE-45-3 with an operating time of 13,000 to 100,000 hours. To study the change in the state of the material under different operating conditions, determine the degree of influence of heat treatment on the regeneration of the microstructure, and restore the mechanical characteristics of the alloy after different periods of operation, non-standard methods were used: relaxation tests on miniature samples to determine the physical yield strength and microplasticity limit and quantitative evaluation of the plasticity coefficient of the material from experimental values of hardness, which allow us to identify the changes occurring in the microvolumes of the material and predict the performance of the product as a whole.

scholarly journals Analysis of the Welding Type and Filler Metal Influence on Performance of a Regenerated Gear

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1496
Author(s):  
Svetislav Marković ◽  
Dušan Arsić ◽  
Ružica R. Nikolić ◽  
Vukić Lazić ◽  
Nada Ratković ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Economic Analysis ◽  
Filler Metal ◽  
Performance Characteristics ◽  
Experimental Investigations ◽  
Spur Gears ◽  
Soft Filler ◽  
Welding Procedure

This paper presents the results of voluminous experimental investigations conducted to analyze the influence of the welding procedure on the performance of regenerated gears. Cylindrical spur gears were tested, both newly manufactured and regenerated, in two fundamentally different ways: by hard facing (surfacing) with the “hard” filler metal (DUR 600-IG) and with the “soft” filler metal (EVB2CrMo) with subsequent cementation and quenching. The regeneration procedures were defined and executed, while, subsequently, the microstructure and microhardness of the hard-faced layers were established and measured, followed by checking the durability of the hard-faced teeth flanks. Finally, techno-economic analysis was performed to establish the rationality of the conducted regenerations, i.e., the costs of regenerated and newly manufactured teeth were compared. Based on the results of the conducted investigations, it was possible to establish the influence of the welding type on the performance characteristics (primarily the service life) of the regenerated gears. For individual reparatory hard facing, the procedure with the “hard” filler metal exhibited better characteristics, while for batch reparation of numerous damaged gears, the reparation with the “soft” filler metal, followed by cementation and heat treatment, might be more convenient.

Structure Improvement on Dual Variable Gear Shaft of the Transmission for ZL50 Wheel Loader

2012 ◽  
Vol 496 ◽  
pp. 50-53
Author(s):  
Zhan Shun Yin ◽  
Yong Wei Han ◽  
Xi Chun Cai
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Dual Variable ◽  
Practical Application ◽  
Hydraulic Pump ◽  
Wheel Loader ◽  
Geometric Tolerance ◽  
Structure Improvement ◽  
Cae Analysis ◽  
Market Feedback

Based on the CAE analysis. The dual variable gear shaft of the transmission for domestic ZL50 wheel loader was redesigned and the processing technology was optimized. The problem of the hardness of the spline which connects the dual variable gear shaft and the working hydraulic pump can not meet the requirements after heat treatment caused by unreasonable design was solved. The problem of the low geometric tolerance and early wear of the spline were solved. After practical application, the market feedback shows that the failure rate, service life and reliability greatly of new designed shaft were enhanced

Advantages of Induction Heat Treatment in the Application of Self-Fluxing Alloy to Boiler Tubes

1998 ◽  
Author(s):  
A. Tomiguchi ◽  
Y. Sochi ◽  
Y. Matsubara
Keyword(s):  
Heat Treatment ◽  
Service Life ◽  
Induction Heating ◽  
Corrosion And Wear ◽  
Hard Coatings ◽  
Heating Process ◽  
Induction Heat ◽  
Induction Heat Treatment ◽  
Boiler Tubes ◽  
Bent Pipe

Abstract This study focuses on two major advantages of induction heating over flame heating in the treatment of coated boiler tubes. In both cases the induction heating process is simple, fast and effective. Firstly, we will show how the the use of induction heating results in exceptionally thick and hard coatings with low porosity. Having high corrosion and wear resistant properties, the products can satisfy industry's needs for reliable coatings with a long service life. Next, the study will detail how a pipe with the coating already applied can be simultaneously bent by induction heating while the coating is melted and fused to the pipe. The result is a thicker, more even and reliable coating than that accomplished by the flame sprayed method on a bent pipe. The process is not only less cumbersome, but again provides a superior product for the market.

scholarly journals Effect of Heat Treatment on the Microstructure and Properties of Ultrafine WC–Co Cemented Carbide

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1302
Author(s):  
Zhongnan Xiang ◽  
Zhanjiang Li ◽  
Fa Chang ◽  
Pinqiang Dai
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Service Life ◽  
Treatment Process ◽  
Cutting Conditions ◽  
Cemented Carbide ◽  
Cemented Carbides ◽  
Heat Treatment Process ◽  
Microstructure And Properties ◽  
Ultrafine Grained

In this paper, the effect of heat treatment on the microstructure and properties of a 0.8 μm WC–10%Co ultrafine cemented carbide was studied. The results show that the microstructural differences in ultrafine WC–Co cemented carbides without and with heat treatment are mainly reflected in the Co phase. For conventional cemented carbides, the hardness and wear resistance can be increased only at the expense of the toughness and strength. An ultrafine-grained WC–Co cemented carbide with good hardness and toughness can be obtained by strengthening the Co phase through an appropriate heat treatment process, and the service life of the ultrafine-grained WC–Co cemented carbide can be improved under actual cutting conditions.

Surface Segregation of Indium by Heat Treatment of Aluminium

2006 ◽  
Vol 519-521 ◽  
pp. 673-678 ◽  
Author(s):  
Brit Graver ◽  
Antonius van Helvoort ◽  
John Charles Walmsley ◽  
Kemal Nisancioglu
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Trace Elements ◽  
Field Emission ◽  
Surface Segregation ◽  
Practical Significance ◽  
Surface Enrichment ◽  
High Temperature Heat Treatment ◽  
Temperature Heat ◽  
Temperature Heat Treatment

High temperature heat treatment of aluminium alloys causes surface enrichment of the trace elements in Group IIIA - VA, specifically the low melting point elements Pb, Bi, In and Sn. The phenomenon has practical significance in promoting certain types of localised corrosion, such as galvanic and filiform corrosion, while mitigating other types, such as pitting corrosion of the bare surface. The purpose of this paper is to investigate the surface enrichment and microstructure of indium relative to the available data for Pb. Model binary AlIn alloys, containing 20-1000 ppm of In, were used after heat treatment at various temperatures. In addition to electrochemical investigations, the microstructures were characterised by field emission scanning electron microscopy (FEG SEM) and field emission transmission electron microscopy (FEG TEM). Heat treatment at temperatures as low as 300°C gave significant segregation of In as opposed to 600°C for Pb. As a result of this and yet unresolved oxide film breakdown mechanism on aluminium, In was significantly more effective than Pb in anodically activating aluminium. These results suggest the possibility that significant activation earlier observed on certain commercial alloys as a result of low temperature heat treatment may be due to the trace elements In.

scholarly journals Changes in Barotolerance, Thermotolerance, and Cellular Morphology throughout the Life Cycle of Listeria monocytogenes

2009 ◽  
Vol 75 (6) ◽  
pp. 1581-1588 ◽  
Author(s):  
Jia Wen ◽  
Ramaswamy C. Anantheswaran ◽  
Stephen J. Knabel
Keyword(s):  
Heat Treatment ◽  
Life Cycle ◽  
Listeria Monocytogenes ◽  
Cellular Morphology ◽  
Practical Significance ◽  
Term Survival ◽  
Long Term Survival ◽  
Whole Milk ◽  
Thermally Processed

ABSTRACT Changes in barotolerance, thermotolerance, and cellular morphology throughout the life cycle of Listeria monocytogenes were investigated. For part 1 of this analysis, L. monocytogenes ATCC 19115 was grown to log, stationary, death, and long-term-survival phases at 35°C in tryptic soy broth with yeast extract (TSBYE). Cells were diluted in whole milk that had been subjected to ultrahigh temperatures (UHT whole milk) and then high-pressure processed (HPP) at 400 MPa for 180 s or thermally processed at 62.8°C for 30 s. As cells transitioned from the log to the long-term-survival phase, the D400 MPa and D62.8°C values increased 10- and 19-fold, respectively. Cells decreased in size as they transitioned from the log to the long-term-survival phase. Rod-shaped cells transitioned to cocci as they entered the late-death and long-term-survival phases. L. monocytogenes strains F5069 and Scott A showed similar results. For part 2 of the analysis, cells in long-term-survival phase were centrifuged, suspended in fresh TSBYE, and incubated at 35°C. As cells transitioned from the long-term-survival phase to log and the stationary phase, they increased in size and log reductions increased following HPP or heat treatment. In part 3 of this analysis, cells in long-term-survival phase were centrifuged, suspended in UHT whole milk, and incubated at 4°C. After HPP or heat treatment, similar results were observed as for part 2. We hypothesize that cells of L. monocytogenes enter a dormant, long-term-survival phase and become more barotolerant and thermotolerant due to cytoplasmic condensation when they transition from rods to cocci. Further research is needed to test this hypothesis and to determine the practical significance of these findings.

The Abrasive Resistance Study about the Cutting Picker 40Cr of Coal Cutter

2013 ◽  
Vol 387 ◽  
pp. 227-230
Author(s):  
Ning Zhang ◽  
Shu Chen Wang ◽  
Na Shi ◽  
Hao Chen
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Service Life ◽  
Labor Intensity ◽  
Surface Wear ◽  
Work Efficiency ◽  
Abrasive Resistance ◽  
Treatment Processes ◽  
Mining Capacity

The cutting pick is primarily used in footing excavation such as coal mining and roadway excavation, so the performance of cutting tooth directly affect the mining capacity, the driving efficiency, and the service life of the tool. The quality of domestic mining pick is lower than that abroad, especially the tooth body wear of the whole shearer picks accounts for half of its overall failure. Thus tooth body 40Cr was treated by various heat treatment processes in this experiment, so as to improve the hardness and wear resistance of cutting tooth, analysis the surface wear scar of morphology, research the wear mechanism, that made for reducing the consumption of cutting tooth, improving work efficiency, and easing the labor intensity of workers undergound.

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