What happens to microstructure during heat treatment?
Tempering of the prevalent unstable martensite precipitates out the carbide particles into the ferrite matrix solution. As a result, microstructural modifications occur, resulting in reduced hardness levels and increased ductility.
What is the purpose of microstructure?
The microstructure of a material can influence its physical properties including corrosion resistance, strength, toughness, ductility, and hardness. These properties help determine how the material will perform in a given application.
How microstructures affect the strength of materials?
The microstructure has a strong influence on the physical characteristics of the material like strength, hardness, corrosion and wear resistance, and ductility. When selecting a material for an industrial application, all these physical properties of the material are taken into consideration.
Does microstructure affect strength?
The microstructure of a material influences its properties such as: tensile strength, reliability, elongation, hardness, toughness, corrosion, magnetic properties, performance under extreme temperatures, directional dependence of properties, etc..
What microstructure tells us?
Microstructure measures describe the amount of each phase, its distribution, and its composition using descriptors of size, shape, and relations between the phases.
Why is microstructure analysis important?
Microstructure analysis is a valuable tool to gain information on how the material was made and the quality of the resulting material. Through a microstructural examination, one can determine if a component was made from specified material and if the material received the proper processing treatment.
How does microstructure affect hardness?
IT is cLearLy concLuded ThaT boTh The sMaLLer grain size and The More precipiTaTions of carbides proMoTe The hardness increasing, buT onLy The sMaLLer grain size increases The corrosion resisTance. This May be caused by differenT effecTs of various MicrosTrucTures on The hardness and corrosion.
What is material microstructure?
Microstructure are material structures seen at the micro level. Specifically, they are structures of an object, organism, or material as revealed by a microscope at magnifications greater than 25 times. When typically mentioned, the microstructure are defects, impurities, grains, and grain boundary.
Are mechanical properties dependent on the microstructure?
The mechanical properties of metallic materials are dependent on their microstructural features, such as grain and sub-grain sizes, grain-boundary phases, their morphology and distribution, dislocations, and dispersed particles.
Why microstructures of metals are different from each other?
The crystalline structure of metals further changes as the metal is worked ( forged, hammered, rolled, extruded,etc) with the crystals being elongated, bent, fractured, and generally deformed plastically.
What is microstructure of steel?
The microstructure is predominantly martensite but also has allotriomorphic ferrite, Widmanstätten ferrite, bainite and pearlite. Notice that the spherical shape of a pearlite colony is obvious in this sample because of the lack of impingment.
What parameters influence the microstructure of an alloy?
The microstructure, texture and mechanical properties of Mg alloy are significantly affected by extrusion parameters, especially by extrusion temperature and speed.
What is the hardness of a martensitic microstructure?
The hardness values are characteristic for a martensitic microstructure. With increasing austenitizing temperature the hardness is rising from 648 (for 1000°) to 754 HV1 after an austenitization at 1100 °C due to the increasing amount of dissolved carbon and chromium in the lattice matrix. A higher ratio of dissolved carbides cause a higher effect of strengthening because of solid solution.
How does austenitizing affect corrosion?
The dissolution of chrome carbides increases the amount of dissolved chrome and carbon. On the one hand, a higher chrome content leads to a passive layer richer in chrome as well and thus to a better corrosion resistance. 5,6 5. R. F. Steigerwald, “The corrosion behavior of some Fe-Cr alloys,” Metall. Trans. 5, 2265–2269 (1974). https://doi.org/10.1007/BF02644005 6. C. Pallotta, N. De Cristofano, R. C. Salvarezza, and A. J. Arvia, “The influence of temperature and the role of chromium in the passive layer in relation to pitting corrosion of 316 stainless steel in NaCl solution,” Electrochim. Acta 31, 1265–1270 (1986). https://doi.org/10.1016/0013-4686 (86)80146-3 On the other hand, a higher carbon content results in lattice distortion which can lead to a more defective passive layer. 1 1. A. F. Candelaria and C. E. Pinedo, “Influence of the heat treatment on the corrosion resistance of the martensitic stainless steel type AISI 420,” J. Mater. Sci. 22, 1151–1153 (2003). https://doi.org/10.1023/a:1025179128333
How long does it take for chromium carbide to dissolve in steel?
It should be noted that ThermoCalc calculations are based on the assumption of equilibrium conditions. After 2 hours of austenitization all carbides that dissolve at the given temperature are dissolved. Considering this the phases should be in equilibrium but as the chromium atom is slow, a complete homogenization is not given even after hours.
What are the effects of heat treatments on the microstructures and tensile properties of dual phase ODS steel
Heat treatments including hot rolling-tempering and normalizing-tempering with air and furna ce-cooling were carefully carried out. The main results are as follows:
Which heat treatment has the highest tensile strength?
HR-T heat treatment has the highest tensile strength, whereas FC shows the lowest tensile strength at room temperature. At an elevated temperature of 700 °C, however, FC has a comparable tensile strength with HR-T and NT.
Can dual phase ODS steel be improved?
This means that dual phase ODS steel can be significantly enhanced by a proper heat treatment process. Based on these results, creep rupture tests are ongoing to improve the strength at high temperature.
Abstract
High chromium cast iron (HCCI) is taken as material of coal water slurry pump impeller, but it is susceptible to produce serious abrasive wear and erosion wear because of souring of hard coal particles.
Author information
Key Laboratory of Pressure Systems and Safety of Ministry of Education, East China University of Science and Technology, Shanghai, 200237, China
Additional information
Supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2013BAF01B01)
