The Influence of Repeated Heating and Cooling Process on the Transformation Characteristics in Ni-Ti Alloy

2010 ◽  
Vol 13 (-1) ◽  
pp. 203-211
Author(s):  
Krzysztof Kuś
Keyword(s):  
Ti Alloy ◽  
Cooling Process ◽  
Repeated Heating ◽  
Heating And Cooling

POTOMAC

Alloy Digest ◽  
1975 ◽  
Vol 24 (8) ◽  
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Heat Treating ◽  
General Purpose ◽  
Low Carbon ◽  
Repeated Heating ◽  
Temperature Changes ◽  
Heating And Cooling ◽  
Temperature Performance ◽  
Heat Checking

Abstract POTOMAC is a general-purpose, low-carbon, chromium-molybdenum-tungsten hot-work steel. It has excellent resistance to shock and heat checking after repeated heating and cooling. Potomac is suitable for hot-work applications involving severe conditions of shock and sudden temperature changes. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fracture toughness. It also includes information on high temperature performance as well as forming, heat treating, and machining. Filing Code: TS-290. Producer or source: Allegheny Ludlum Corporation.

scholarly journals Formation of Incrustations during the Cocombustion of Biomass in Fluidised Bed Boilers

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Petr Buryan
Keyword(s):  
Raw Materials ◽  
Combustion Process ◽  
Power Equipment ◽  
Fluidised Bed ◽  
Boiler Furnace ◽  
Repeated Heating ◽  
Equipment Operation ◽  
Heating And Cooling ◽  
First Pass ◽  
Pass Through

In this article, we focus on causes of formation of incrustations in fluidised bed boilers that result from combustion of biomass-containing energy-producing raw materials and can significantly limit the efficiency of the respective power equipment operation. We applied laboratory procedures followed for assessment of characteristic eutectics of mixtures of coal ashes, desulphurisation components (dolomite and limestone), and woodchip ashes. Our analysis proved that combustion of these (or similar) raw materials, accompanied by repeated heating and cooling of combustion and flue gas desulphurisation products, leads to the formation of unfavourable incrustations. These incrustations can grow up to several tens of centimetres in size, thereby significantly restricting the power equipment functionality. They arise due to incrust reheating that results in the formation of eutectics, which have lower melting temperatures than that during their first pass through the combustion process. The same holds for desulphuriation components themselves. Formation of these new eutectics can be attributed both to recycling of substances produced during the first pass through the furnace as well as to mixtures formed both from recycled materials and from components initially combusted in the boiler furnace.

scholarly journals Analytical Modeling of Residual Stress in Laser Powder Bed Fusion Considering Part’s Boundary Condition

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 337 ◽  
Author(s):  
Elham Mirkoohi ◽  
Hong-Chuong Tran ◽  
Yu-Lung Lo ◽  
You-Cheng Chang ◽  
Hung-Yu Lin ◽  
...  
Keyword(s):  
Residual Stress ◽  
Thermal Stress ◽  
Kinematic Hardening ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Repeated Heating ◽  
Powder Bed ◽  
Heating And Cooling ◽  
Body Load ◽  
Point Body

Rapid and accurate prediction of residual stress in metal additive manufacturing processes is of great importance to guarantee the quality of the fabricated part to be used in a mission-critical application in the aerospace, automotive, and medical industries. Experimentations and numerical modeling of residual stress however are valuable but expensive and time-consuming. Thus, a fully coupled thermomechanical analytical model is proposed to predict residual stress of the additively manufactured parts rapidly and accurately. A moving point heat source approach is used to predict the temperature field by considering the effects of scan strategies, heat loss at part’s boundaries, and energy needed for solid-state phase transformation. Due to the high-temperature gradient in this process, the part experiences a high amount of thermal stress which may exceed the yield strength of the material. The thermal stress is obtained using Green’s function of stresses due to the point body load. The Johnson–Cook flow stress model is used to predict the yield surface of the part under repeated heating and cooling. As a result of the cyclic heating and cooling and the fact that the material is yielded, the residual stress build-up is precited using incremental plasticity and kinematic hardening behavior of the metal according to the property of volume invariance in plastic deformation in coupling with the equilibrium and compatibility conditions. Experimental measurement of residual stress was conducted using X-ray diffraction on the fabricated IN718 built via laser powder bed fusion to validate the proposed model.

Influence of the Mo and V Contents on Microstructure and Secondary Hardening of 6Cr6W2MoV Steel

2014 ◽  
Vol 936 ◽  
pp. 1267-1272 ◽  
Author(s):  
Xiao Jing Zhang ◽  
Yong Qing Ma ◽  
Yu Fen Liang ◽  
Guo Fang Liu
Keyword(s):  
Secondary Hardening ◽  
Equilibrium Thermodynamic ◽  
Cooling Process ◽  
Transformation Mechanism ◽  
Tempering Temperature ◽  
Heating And Cooling ◽  
Carbide Size ◽  
Process Factors ◽  
Mo Content ◽  
Carbide Particles

The influence of Mo and V contents on the microstructure and secondary hardening of 6Cr6W2MoV steel was studied in this paper, and the process factors and the transformation mechanism of the influence results were discussed by phase equilibrium thermodynamic analysis. The results show that, the microstructure of 6Cr6W2MoV steel is uniform and thin, in which the undissolved carbide size after quenching is 0.23μm. In the heating and cooling process of the annealing, the dissolution and precipitation of M23C6↔M6C carbides transformation can be used to carbides distributing uniform refinement. Adding an overmany Mo content will lead to coarsening of carbide particles due to small amplitude of M23C6↔M6C transformation. Adding an overmany V content will appear a small of the bulk MC carbide on the crystallization, so the heterogeneity of carbides is increasing. The tempering hardness of 6Cr6W2MoV steel is 63.5HRC, and when adding an overmany Mo content the maximal hardness arrives to 65HRC. Adding Mo changes the carbide composing, it is conducive to the variety of carbides precipitation strengthening near intermediate temperature and the tempering hardness increasing. When adding an overmany V content the more MC carbide well occupy more amount of C, the tempering temperature dispersion increases too, so the tempering hardness debases deservedly and the highest hardness only reaches HRC60.5.

A STUDY ON EVALUATION OF RESIDUAL STRESS BY MULTILAYER WELDING

2011 ◽  
Vol 25 (31) ◽  
pp. 4285-4288 ◽  
Author(s):  
SUN-CHUL HUH ◽  
JONG-SEOK LEE ◽  
GWI-NAM KIM ◽  
WON-JO PARK ◽  
JOUN-SUNG PARK ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Strength ◽  
Optical Microscope ◽  
Welding Residual Stress ◽  
Surface Microstructure ◽  
Repeated Heating ◽  
Heating And Cooling ◽  
Ansys Analysis ◽  
Large Structures ◽  
Welding Technology

Today, ships and structures are becoming larger (large structures, vessels, FPSO, etc.). Thus, high-strength welding material is required. The advantages of welding over other joining methods, depending on the development of welding technology, include such things as ease of operation and the structures of simplification and the confidential excellence, etc. However, shrinkage and deformation also occur, because of the repeated heating and cooling. Welding residual stress has an adverse effect on stability, but, it was closely related fatigue strength and brittle fracture of structures. In this study, experimental and analysis were conducted, and AIS3000 used to measure residual stress, which were compare with ANSYS analysis results. Metal surface microstructure was observed at various weld spots, as well as HAZ, and base metal using the optical microscope, and component analysis and crystal plane were measured using an XRD and EPMA.

scholarly journals The use of the T-history method to estimate thermal capacity and latent heat for RT15 and RT18 materials

2018 ◽  
Vol 70 ◽  
pp. 01008
Author(s):  
Paulina Kapica ◽  
Jarosław Karwacki ◽  
Sebastian Bykuć
Keyword(s):  
Latent Heat ◽  
Measurement Method ◽  
Phase Change Materials ◽  
Thermal Capacity ◽  
Temperature Dependency ◽  
Cooling Process ◽  
Heating And Cooling ◽  
Theoretical Assumptions ◽  
Trade Names ◽  
Research Equipment

The paper presents theoretical assumptions and implementation of the T-history method, which was used to estimate the thermal capacity and latent heat for phase change materials (PCMs). The research equipment, measurement system and obtained results were discussed. The T-history method was used to investigate the heating and cooling process of two PCMs, sold under the trade names of RT15 and RT18. Obtained results were compared with the manufacturer’s data. The analysis of the research results has led to the conclusion that the presented measurement method made it possible to perform a preliminary verification of the enthalpy–temperature dependency of the PCMs. The method can be also used for studying different commercial materials and estimating this dependency for materials of yet unknown properties.

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