Heat treatments are useful methods to change the matrix microstructure for the improvement of impact toughness and wear resistance for numerous cast iron materials. These treatments provide relatively few benefits in improving the impact toughness of the HCCI with even larger amount of hard consecutive eutectic chromium carbides [ 8 ].
Does heat treatment affect mechanical properties and microstructure change of selected specimen?
The microhardness gradually decreases with increasing temperature when the TC4 SLM part is treated below the critical temperature. Conversely, the microhardness increases significantly with increasing temperature when the TC4 SLM part is treated …
Do heat treatments affect ODS steel microstructure?
Jan 01, 2021 · The heating and cooling treatment of the steel specimens have a great effect on the phase of the microstructure of the steel specimen. The addition of alloys or coarsening of the austenitic grain structure increase the hardenability of steel.
What are the advantages of heat treatment in machining?
Nov 01, 2013 · Microstructures after three kinds of heat treatments are significantly different and very fine grains are formed after NT heat treatment, while HR-T and FC heat treatment induces coarsened grains. An NT specimen has a typical tempered martensite structure consisting of very fine martensitic grains with finely dispersed carbides along the grain boundaries.
Does heat treatment affect microstructure and mechanical properties of En31 and EN8?
Aug 16, 2014 · 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. The research on optimization of heat treatments to improve abrasive wear properties of HCCI is insufficient, so effect of heat treatments on the …
How does heat treating change the microstructure?
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 happens to the microstructure during tempering?
Changes in Martensite Structure The martensite itself also changes during tempering. One change that occurs is that the “tetragonality” of the martensite is reduced as the martensite becomes more and more like cubic ferrite as the carbon leaves the martensite.Apr 23, 2018
What happens to the microstructure of a steel after tempering?
Tempering involves a three-step process in which unstable martensite decomposes into ferrite and unstable carbides, and finally into stable cementite, forming various stages of a microstructure called tempered martensite.
What happens to the microstructure and the properties of martensite during tempering?
It is attributed to the formation of cementite particles at the martensite lath boundaries and within the laths. During tempering, the particles coarsen and become large enough to crack, thus providing crack nuclei which may then propagate into the matrix.
Does tempering affect grain structure?
One of the common treatments to achieve this is quenching and tempering. This is a process that strengthens and hardens iron-based alloys by heating, rapidly cooling, and reheating. When steel is heated above a certain point, the grain (molecular) structures are changed.Mar 13, 2018
What does quenching do to microstructure?
The rapid quenching changes the crystal structure of the steel, compared with a slow cooling. Depending on the carbon content and alloying elements of the steel, it can get left with a harder, more brittle microstructure, such as martensite or bainite, when it undergoes the quench hardening process.May 9, 2019
What is the significance of microstructure in the material properties?
The microstructure of a material (such as metals, polymers, ceramics or composites) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high/low temperature behaviour or wear resistance.
How does heating and cooling affect the microstructure of steel?
The heating and cooling treatment of the steel specimens have a great effect on the phase of the microstructure of the steel specimen. The addition of alloys or coarsening of the austenitic grain structure increase the hardenability of steel.
What is the purpose of heat treating steel?
The purpose of heat treating is to analyze the mechanical properties of the steel, usually ductility, hardness, Yield strength, tensile strength and impact resistance. The heat treatment develops hardness, softness, and improves the mechanical properties such as tensile strength, yield strength, ductility, corrosion resistance and creep rupture.
Why is mechanical testing important?
Today, more concern is being given to the interpretation of test results in terms of service performance, as well as giving reliable indications of the ability of the material to perform certain types of duty.
Can mechanical properties be modified?
The mechanical properties can easily be modified by heat treating to suit a particular design purpose. In the present study, selected samples are heat-treated at certain temperature above the austenitic region and quenched in order to investigate the effect on the mechanical properties and microstructure of the steel.
Does normalizing steel soften it?
It resulted in formation of pearlite and ferrite phases in steel specimens. Normalizing does not soften the steel to the extent it is done by annealing and also it does not restore ductility as much as is done by annealing. Its Vicker Hardness Number is less than hardening but greater than annealing. 3.1.2.
1. INTRODUCTION
Oxide dispersion strengthened (ODS) steel is the most promising candidate structural material for next-generation nuclear systems such as Gen. IV fission and DEMO fusion reactors, because of its excellent elevated temperature strength [ 1 ], corrosion [ 2] and radiation resistance [ 3 ].
2. EXPERIMENTAL PROCEDURE
The dual phase ODS steels used in this study are Fe-10Cr-2W and Fe-12Cr-1Mo in wt% with alloying elements including W, Ni, Ti, Ta, V, and C. These ODS steels have been designed by the control of ferrite and austenite formers, which are Cr, W and Ni, C in Fe-based alloys at the consolidation temperature of around 1150 °C.
4. CONCLUSIONS
In the present study, the effects of heat treatments on the microstructures and tensile properties of dual phase ODS steels were investigated to enhance the high strength at elevated temperature. Heat treatments including hot rolling-tempering and normalizing-tempering with air and furnace-cooling were carefully carried out.
ACKNOWLEDGMENTS
This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (No. 2012M2A8A1027872).
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)
