Microstructure Evolution during Quenching and Tempering of Martensite in a Medium C Steel

2012 ◽  
Vol 715-716 ◽  
pp. 860-865 ◽  
Author(s):  
Andrea di Schino ◽  
Laura Alleva ◽  
Mauro Guagnelli
Keyword(s):  
Thermal Strain ◽  
Orientation Imaging Microscopy ◽  
Austenite Grain Size ◽  
Tempering Temperature ◽  
Orientation Imaging ◽  
Bainitic Steels ◽  
Heat Treated ◽  
Quenching Process ◽  
Prior Austenite Grain Size ◽  
Quenching And Tempering

The microstructural evolution of a quenched medium-C steel during tempering was analyzed by means of Orientation Imaging Microscopy (OIM). The steel was heat treated in order to develop fully martensitic microstructures after quenching with a different prior austenite grain size (AGS). Main results can be summarized as below: A very poor effect of AGS on packet size was found in comparison to bainitic steels. A finer packet was measured at mid-thickness with respect to surface after the quenching process. This phenomenon was attributed to the effect of thermal strain path on phase transformation during quenching. The through-thickness microstructural gradient remains after tempering. High-angle boundary grains do not significantly grow after tempering; on the contrary, low-angle grain boundaries (cells) move, fully justifying the hardness evolution with tempering temperature.

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.

Effect of a Complex Heat Treatment on the Structure of 300M Steel

1981 ◽  
Vol 39 ◽  
pp. 312-313
Author(s):  
R. Padmanabhan ◽  
W. E. Wood
Keyword(s):  
Heat Treatment ◽  
Metal Carbides ◽  
Austenite Grain Size ◽  
300M Steel ◽  
Heat Treated ◽  
Strain Fracture ◽  
Prior Austenite Grain Size ◽  
Short Time ◽  
Final Tempering ◽  
Similar Yield

Intermediate high temperature tempering prior to subsequent reaustenitization has been shown to double the plane strain fracture toughness as compared to conventionally heat treated UHSLA steels, at similar yield strength levels. The precipitation (during tempering) of metal carbides and their subsequent partial redissolution and refinement (during reaustenitization), in addition to the reduction in the prior austenite grain size during the cycling operation have all been suggested to contribute to the observed improvement in the mechanical properties. In this investigation, 300M steel was initially austenitized at 1143°K and then subjected to intermediate tempering at 923°K for 1 hr. before reaustenitizing at 1123°K for a short time and final tempering at 583°K. The changes in the microstructure responsible for the improvement in the properties have been studied and compared with conventionally heat treated steel. Fig. 1 shows interlath films of retained austenite produced during conventionally heat treatment.

Carbide composition changes in a low alloy steel

1990 ◽  
Vol 48 (2) ◽  
pp. 420-421
Author(s):  
Z. Larouk ◽  
R. Pilkington
Keyword(s):  
Alloy Steel ◽  
Prior Austenite ◽  
Creep Behaviour ◽  
Low Alloy Steel ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Heat Treated ◽  
Prior Austenite Grain Size ◽  
Composition Changes ◽  
Prior Austenite Grain

Durehete 1055 is a 1%Cr1%Mo¾%V low alloy steel used as bolting material at 565°C. It also contains 0.08%Ti and 0.005%B to improve the creep behaviour, but deleterious properties have been reported, due to the presence of trace elements such as P and Sn. The present work has been an attempt to understand this problem by examining three vacuum melted casts of this steel containing selected additions (wt.%) of 1) 0.08 Ti, 2) 0.08 Ti and 0.02 P; and 3) 0.08 Ti and 0.02 Sn. The material was heat treated for 2h at 980°C, W.Q., and tempered 4h at 680°C, giving a prior austenite grain size of 8 μm. Specimens were then crept for various times at 565°C. After test, metallographic samples were prepared from both the gauge lengths (stressed) and heads (unstressed) to enable the production of carbon extraction replicas. These replicas were examined in a Philips 400T electron microscope, and carbides analysed using EDS.

The effect of heat treatment on mechanical properties of 42CrMo4 steel

2020 ◽  
Vol 1 (98) ◽  
pp. 5-10
Author(s):  
A. Çalık ◽  
O. Dokuzlar ◽  
N. Uçar
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Stress ◽  
Yield Stress ◽  
Impact Energy ◽  
Ultimate Tensile Stress ◽  
Tempering Temperature ◽  
Heat Treated ◽  
Quenching Process ◽  
42Crmo4 Steel

Purpose: In this study, the effect of heat treatment on the microstructure and mechanical properties of 42CrMo4 steel were investigated. Design/methodology/approach: The samples were annealed at 860°C for 120 min. followed by oil quenching and then tempered at temperatures between 480 and 570°C for 120 min. The microstructure of untreated 42CrMo4 steel mainly consists of pearlite and ferrite whereas the microstructure was found to be as a martensitic structure with a quenching process. Findings: The results showed that there is an increase in yield stress, ultimate tensile stress, hardness and impact energy, while elongation decreases at the end of the quenching process. Conversely, yield stress, ultimate tensile stress and hardness decrease slightly with the increasing of tempering temperature, while elongation and impact energy increase. Research limitations/implications: Other types of steels can be heat treated in a wider temperature range and the results can be compared. Practical implications: It is a highly effective method for improving the mechanical properties of heat treatment materials. Originality/value: A relationship between the mechanical properties and the microstructure of materials can be developed. The heat treatment is an effective method for this process.

scholarly journals Microstructure and Mechanical Properties of Heat-treated T92 Martensitic Heat Resistant Steel

2017 ◽  
Vol 36 (8) ◽  
pp. 771-778 ◽  
Author(s):  
P. Rajesh Kannan ◽  
V. Muthupandi ◽  
B. Arivazhagan ◽  
K. Devakumaran
Keyword(s):  
Lath Martensite ◽  
Austenite Grain Size ◽  
Heat Resistant Steel ◽  
Hardness Tester ◽  
Heat Treated ◽  
Prior Austenite Grain Size ◽  
Grain Boundary Decohesion ◽  
The Given ◽  
Hardness Values ◽  
Martensite Microstructure

AbstractT92 samples were solutionized at 1,050 °C, 1,100 °C and 1,150 °C for 20 min and then tempered at 730 °C, 745 °C and 760 °C for 60 min. Optical microscopy studies were carried out to understand the microstructural evolution due to heat treatment. These heat-treated samples comprised of lath martensite microstructure in all the cases. Prior austenite grain size of the heat-treated samples increased with solutionizing temperature. Tensile properties were evaluated using micro-tensile samples. Hardness values of the heat-treated samples were estimated using Vickers hardness tester. Interestingly, for all the given tempering condition, the hardness values showed an increasing trend with solutionizing temperature while their tensile strength values tend to decrease. Fractograph analysis depicted that increasing the solutionizing temperature led to grain boundary decohesion.

Influence of Repeated Quenching-Tempering on Fisheye Cracks around Tin and Al2O3 Inclusions in SAE 52100 Steel

2013 ◽  
Vol 300-301 ◽  
pp. 1298-1303 ◽  
Author(s):  
Koshiro Mizobe ◽  
Takashi Honda ◽  
Hitonobu Koike ◽  
Edson Costa Santos ◽  
Takuya Shibukawa ◽  
...  
Keyword(s):  
High Strength ◽  
Bearing Steel ◽  
Rolling Contact ◽  
High Carbon ◽  
Austenite Grain Size ◽  
Repeated Heating ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Quenching And Tempering ◽  
Prior Austenite Grain

Martensitic high-carbon high-strength SAE 52100 bearing steel has been widely used as the main alloys for rolling contact applications, and also at the components under bending and tension-compression. In order to enhance the material’s strength, refining the prior austenite grain size through repeated heating has been investigated. In this work, the microstructure of repeatedly quenched-tempered Ti, N-rich SAE 52100 steel was investigated. The material was melted by an electric furnace and formed by continuous casting and forging, and the crack origin on the fracture surface was investigated. It was found that repeated furnace quenching and tempering effectively refined the martenstic structure.

scholarly journals EFFECT OF AUSTENITIC GRAIN SIZE ON THE PHASE TRANSFORMATION OF A NOVEL 6.5% Cr STEEL FOR FORGED COMPONENTS

2021 ◽  
Vol 25 (1) ◽  
pp. 18-23
Author(s):  
Andrea Di Schino
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Chemical Elements ◽  
Austenite Grain Size ◽  
Cr Content ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Quenching And Tempering ◽  
Austenitic Grain Size ◽  
Prior Austenite Grain

In this paper the effect of quenching and tempering (Q&T) thermal treatment on mechanical properties of a novel 6.5% Cr steel for forged components is studied. The main innovation is in the increased hardenability following the higher Cr content with respect to the more common 5% Cr steel allowing to lower the content of other chemical elements aimed to achieve the target mechanical properties. Following to the high intrinsic hardenability of such steel based on the Cr content a poor effect of prior austenite grain size should be expected after quenching. Aim of this work is to evaluate such effect and to analyse the dependence of mechanical properties on it.

scholarly journals On a Modified Approach of Measuring Quench Severity and its Application

2021 ◽  
Author(s):  
Viraj A. Athavale ◽  
Mario Buchely ◽  
Laura Bartlett ◽  
Ronald O’Malley ◽  
David C. Van Aken
Keyword(s):  
Grain Size ◽  
Prior Austenite ◽  
Empirical Method ◽  
Hardness Profile ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Profile Matching ◽  
Heat Treated ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

Abstract Instrumented methods for measuring the coefficient of heat transfer are difficult to implement in industrial quench systems. In 1985 Roy Kern presented a simple empirical method for calculating the quench severity of commercial quench systems using measured Jominy hardenability and a mid-radius (r/R=0.5) hardness of a 3-inch diameter 8640 or 4140 steel bar. A more general approach using the Kern methodology is presented here with hardness profile matching to determine the quench severity. Experiments were performed using 2-inch diameter bars of 8620 with a length to diameter ratio of 4. Test bars and Jominy bars were heat-treated following ASTM A255. Test bars were quenched using an experimental draft tube with a water velocity of 6 ft/s. An excel workbook was programmed to calculate the quenched hardness profile as a function of quench severity using prior austenite grain size and steel chemistry. Measured Jominy hardness and calculated hardenability were in good agreement provided the prior austenite grain size was incorporated into the calculations. Both the Kern method and hardness profile matching produced a quench severity equal to 1.45.

scholarly journals EFFECT OF AUSTENITIC GRAIN SIZE ON THE PHASE TRANSFORMATION OF A NOVEL 6.5% CR STEEL FOR FORGED COMPONENTS

2019 ◽  
Vol 25 (1) ◽  
pp. 18
Author(s):  
Andrea Di Schino
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Prior Austenite ◽  
Austenite Grain Size ◽  
Cr Content ◽  
Austenite Grain ◽  
Prior Austenite Grain Size ◽  
Quenching And Tempering ◽  
Austenitic Grain Size ◽  
Prior Austenite Grain

<p class="AMSmaintext"><span lang="EN-GB">In this paper the effect of quenching and tempering (Q&amp;T) thermal treatment on mechanical properties of a novel 6.5% Cr steel for forged components is studied. Main innovation of such steel is in the increased hardenability following the Cr content with respect to the more common 5% Cr steel allowing to add lower content of other elements aimed to achieve the target mechanical properties. Following to the high intrinsic hardenability of such steel based on the Cr content a poor effect of prior austenite grain size should be expected after quenching.  Aim of this work is to evaluate such effect and to analyse the dependence of mechanical properties on it. </span></p>

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