Accelerated spheroidization of hypoeutectoid steel by the decomposition of supercooled austenite

1986 ◽  
Vol 21 (9) ◽  
pp. 3339-3344 ◽  
Author(s):  
Chen -Chia Chou ◽  
Po -We Kao ◽  
Gwo -Hwa Cheng
Keyword(s):  
Supercooled Austenite ◽  
Accelerated Spheroidization ◽  
Hypoeutectoid Steel

Modeling Phase Transformation Kinetics and Their Effect on Hardness and Hardness Depth in Laser Hardening of Hypoeutectoid Steel

2015 ◽  
Author(s):  
Suhash Ghosh ◽  
Chittaranjan Sahay
Keyword(s):  
Thermal Analysis ◽  
Phase Transformation ◽  
Phase Transformations ◽  
Laser Hardening ◽  
Temperature History ◽  
Transformation Kinetics ◽  
Continuous Cooling ◽  
Phase Transformation Kinetics ◽  
Hardness Depth ◽  
Hypoeutectoid Steel

Much research has been done to model laser hardening phase transformation kinetics. In that research, assumptions are made about the austenization of the steel that does not translate into accurate hardness depth calculations. The purpose of this paper is to develop an analytical method to accurately model laser hardening phase transformation kinetics of hypoeutectoid steel, accounting for non-homogeneous austenization. The modeling is split into two sections. The first models the transient thermal analysis to obtain temperature time-histories for each point in the workpiece. The second models non-homogeneous austenization and utilizes continuous cooling curves to predict microstructure and hardness. Non-homogeneous austenization plays a significant role in the hardness and hardness depth in the steel. A finite element based three-dimensional thermal analysis in ANSYS is performed to obtain the temperature history on three steel workpieces for laser hardening process with no melting; AISI 1030, 1040 and 1045 steels. This is followed by the determination of microstructural changes due to ferrite and pearlite transformation to austenite during heating and the subsequent austenite to martensite and other diffusional transformations during cooling. Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation is used to track the phase transformations during heating, including the effects of non-homogenous austenitization. The solid state nodal phase transformations during cooling are monitored on the material’s digitized Continuous Cooling Transformation (CCT) curve through a user defined input file in ANSYS for all cooling rates within the Heat Affected Zone (HAZ). Material non-linearity is included in the model by including temperature dependent thermal properties for the material. The model predictions for hardness underneath the laser and the HAZ match well with the experimental results published in literature.

Transformations of Supercooled Austenite in Promising High-Hardenability Machine Steels

2018 ◽  
Vol 60 (5-6) ◽  
pp. 339-347 ◽  
Author(s):  
M. V. Maisuradze ◽  
M. A. Ryzhkov ◽  
O. A. Surnaeva
Keyword(s):  
Supercooled Austenite ◽  
High Hardenability

Decomposition of supercooled austenite of powder phosphorus steels

1999 ◽  
Vol 41 (5) ◽  
pp. 193-197
Author(s):  
V. N. Antsiferov ◽  
S. A. Oglezneva ◽  
A. A. Shatsov
Keyword(s):  
Supercooled Austenite
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