The effect of austenite grain size and tempering temperature on the cold-brittleness threshold of steel

1970 ◽  
Vol 12 (3) ◽  
pp. 201-205
Author(s):  
I. V. Shermazan ◽  
V. D. Zelenova ◽  
A. P. Gulyaev
Keyword(s):  
Grain Size ◽  
Cold Brittleness ◽  
Austenite Grain Size ◽  
Tempering Temperature ◽  
Austenite Grain ◽  
Cold Brittleness Threshold

Microstructure Evolution during Tempering of Martensite in a Medium-C Steel

2007 ◽  
Vol 558-559 ◽  
pp. 1435-1441 ◽  
Author(s):  
Andrea di Schino ◽  
Paolo Emilio di Nunzio ◽  
Gustavo Lopez Turconi
Keyword(s):  
Grain Size ◽  
Grain Boundaries ◽  
Orientation Imaging Microscopy ◽  
Packet Size ◽  
High Angle ◽  
Austenite Grain Size ◽  
Tempering Temperature ◽  
Orientation Imaging ◽  
Austenite Grain ◽  
Prior Austenite Grain Size

To identify the characteristic microstructural length determining the mechanical properties of a quenched and tempered medium-C steel and its dependence on the prior austenite grain size, different tempering treatments have been carried out after a fully martensitic quenching. The resulting microstructures have been analyzed by Orientation Imaging Microscopy (OIM) and two kind of features have been taken into consideration: packets (i.e. domains delimited by high-angle boundaries) and cells (domains bounded by low-angle grain boundaries). The main results can be summarized as follows: 1. A very weak effect of austenite grain size on packet size was found. 2. A finer packet size was measured at mid-thickness with respect to surface after external and internal water quenching process. This phenomenon was attributed to the effect of the strain path on the phase transformation during quenching. 3. The through-thickness microstructural gradient remains substantially unchanged after tempering. 4. Grains with high-angle boundaries do not significantly grow after tempering; on the contrary, low-angle grain boundaries move, fully justifying the hardness evolution with the tempering temperature.

The effect of heat treatment on the mechanical properties of a low carbon steel (0.1%) for offshore structural application

2012 ◽  
Vol 226 (3) ◽  
pp. 242-251 ◽  
Author(s):  
Sung S Kang ◽  
Amir Bolouri ◽  
Chung-Gil Kang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Cooling Rate ◽  
Impact Energy ◽  
Cast Steel ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Tempering Temperature ◽  
Austenite Grain

In this study, a low carbon cast steel (0.1% C) alloy designed for offshore structures, and the mechanical properties of the alloy under different heat treatment cycles have been evaluated. The effect of austenitizing time on the austenite grain size was studied. Subsequently, the quenched samples with minimum austenite grain size subjected to tempering experiments at different tempering temperatures (450 °C, 550 °C, and 650 °C) and cooling rates (0.23, 36, and 50 °C/s) from the temperature. The results showed that by increasing the austenitizing time, the austenite grain size initially decreased and reached the minimum value with ASTM number of 6.35 and then followed by an increase. When the tempering temperature increased, yield and tensile strengths decreased, whereas the ductility properties improved. In addition, yield and tensile strengths were not affected by cooling rate from tempering temperature, whereas the ductility properties were slightly affected. The increase in tempering temperature significantly led to improvement in the toughness to fracture of the alloy. The effect of cooling rate on impact energy for the samples tempered at 450 °C and 550 °C was negligible. By the contrast, impact energy for the samples tempered at 650 °C was markedly affected by cooling rate, in which the highest value was achieved for a cooling rate of 50 °C/s.

scholarly journals A New Systematic Approach Based on Dilatometric Analysis to Track Bainite Transformation Kinetics and the Influence of the Prior Austenite Grain Size

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 324
Author(s):  
David San-Martin ◽  
Matthias Kuntz ◽  
Francisca G. Caballero ◽  
Carlos Garcia-Mateo
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Prior Austenite ◽  
Bainitic Transformation ◽  
Transformation Rate ◽  
Transformation Kinetics ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

This investigation explores the influence of the austenitisation heat treatment and thus, of the prior austenite grain size (PAGS), on the kinetics of the bainitic transformation, using as A case study two high-carbon, high-silicon, bainitic steels isothermally transformed (TIso = 250, 300, 350 °C), after being austenised at different temperatures (γTγ = 925–1125 °C). A methodology, based on the three defining dilatometric parameters extracted from the derivative of the relative change in length, was proposed to analyse the transformation kinetics. These parameters are related to the time to start bainitic transformation, the time lapse for most of the transformation to take place and the transformation rate at the end of the transformation. The results show that increasing the PAGS up to 70 µm leads to an increase in the bainite nucleation rate, this effect being more pronounced for the lowest TIso. However, the overall transformation kinetics seems to be weakly affected by the applied heat treatment (γTγ and TIso). In one of the steels, PAGS > 70 µm (γTγ > 1050 °C), which weakly affects the progress of the transformation, except for TIso = 250 °C, for which the enhancement of the autocatalytic effect could be the reason behind an acceleration of the overall transformation.

scholarly journals Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1988
Author(s):  
Tibor Kvackaj ◽  
Jana Bidulská ◽  
Róbert Bidulský
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Strength Steel ◽  
Single Phase ◽  
Hsla Steel ◽  
High Strength ◽  
Strength Properties ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Steel Grades

This review paper concerns the development of the chemical compositions and controlled processes of rolling and cooling steels to increase their mechanical properties and reduce weight and production costs. The paper analyzes the basic differences among high-strength steel (HSS), advanced high-strength steel (AHSS) and ultra-high-strength steel (UHSS) depending on differences in their final microstructural components, chemical composition, alloying elements and strengthening contributions to determine strength and mechanical properties. HSS is characterized by a final single-phase structure with reduced perlite content, while AHSS has a final structure of two-phase to multiphase. UHSS is characterized by a single-phase or multiphase structure. The yield strength of the steels have the following value intervals: HSS, 180–550 MPa; AHSS, 260–900 MPa; UHSS, 600–960 MPa. In addition to strength properties, the ductility of these steel grades is also an important parameter. AHSS steel has the best ductility, followed by HSS and UHSS. Within the HSS steel group, high-strength low-alloy (HSLA) steel represents a special subgroup characterized by the use of microalloying elements for special strength and plastic properties. An important parameter determining the strength properties of these steels is the grain-size diameter of the final structure, which depends on the processing conditions of the previous austenitic structure. The influence of reheating temperatures (TReh) and the holding time at the reheating temperature (tReh) of C–Mn–Nb–V HSLA steel was investigated in detail. Mathematical equations describing changes in the diameter of austenite grain size (dγ), depending on reheating temperature and holding time, were derived by the authors. The coordinates of the point where normal grain growth turned abnormal was determined. These coordinates for testing steel are the reheating conditions TReh = 1060 °C, tReh = 1800 s at the diameter of austenite grain size dγ = 100 μm.

The effect of austenite grain size on deformation mechanism of Fe–17Mn steel

2021 ◽  
Vol 809 ◽  
pp. 140972
Author(s):  
Jin-Young Lee ◽  
Jin-Sung Hong ◽  
Seok-Hyeon Kang ◽  
Young-Kook Lee
Keyword(s):  
Grain Size ◽  
Deformation Mechanism ◽  
Austenite Grain Size ◽  
Austenite Grain

Austenite Grain Evolution Mechanism of High Carbon Rail Based on Thermal Technology

2020 ◽  
Vol 837 ◽  
pp. 74-80
Author(s):  
Jun Yuan ◽  
Zhen Yu Han ◽  
Yong Deng ◽  
Da Wei Yang
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Rail Steel ◽  
Heating Temperature ◽  
Great Influence ◽  
Stable Operation ◽  
High Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains

In view of the special requirements of rails to ensure the safe and stable operation of Railways in China, the formation characteristics of austenite grains in high carbon rail are revealed through industrial exploration, the process of industrial rail heating and rolling is simulated, innovative experimental research methods such as different heating and heat treatment are carried out on the actual rails in the laboratory. Transfer characteristics of austenite grain size, microstructures and key properties of high carbon rail during the process are also revealed. The results show that the austenite grain size of industrial produced U75V rail is about 9.0 grade. When the holding temperature is increased from 800 C to 1300 C, the austenite grain size of high carbon rail steel decreases, the austenite grain are gradually coarsened, and the tensile strength increases slightly. The tensile strength is affected by the heating temperature. With the increase of heating temperature, the elongation and impact toughness of high carbon rail decrease. The heating temperature of high carbon rail combined with austenite grain size shows that the heating temperature has a great influence on austenite grain size, and has the most obvious influence on the toughness of high carbon rail.

Effects of Initial Austenite Grain Size on Microstructure and Mechanical Properties of 5% Nickel Cryogenic Steel

2019 ◽  
Vol 8 (2) ◽  
pp. 241-248 ◽  
Author(s):  
Tao Xiong ◽  
Guang Xu ◽  
Qing Yuan ◽  
Hai-jiang Hu ◽  
Jun-yu Tian
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Microstructure And Mechanical Properties ◽  
Cryogenic Steel

Influence of austenite grain size on recrystallisation–precipitation interaction in a V-microalloyed steel

2007 ◽  
Vol 447 (1-2) ◽  
pp. 11-18 ◽  
Author(s):  
A. Quispe ◽  
S.F. Medina ◽  
M. Gómez ◽  
J.I. Chaves
Keyword(s):  
Grain Size ◽  
Microalloyed Steel ◽  
Austenite Grain Size ◽  
Austenite Grain

Effects of Molybdenum Additions on the Structure, Depth, and Austenite Grain Size of the Case of Carburized 0.13% Carbon Steels

2002 ◽  
Vol 11 (6) ◽  
pp. 625-630 ◽  
Author(s):  
Kazi Md. Shorowordi ◽  
Md. Mohar Ali Bepari
Keyword(s):  
Grain Size ◽  
Carbon Steels ◽  
Austenite Grain Size ◽  
Austenite Grain
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