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.

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.

Fracture toughness relationships in a low-alloy steel

1983 ◽  
Vol 41 ◽  
pp. 224-225
Author(s):  
R. Padmanabhan ◽  
W. E. Wood
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Plane Strain Fracture Toughness ◽  
Low Alloy Steel ◽  
Heat Treated ◽  
Strain Fracture ◽  
Conventional Heat Treatment ◽  
Microstructural Effects ◽  
Improve Fracture Toughness ◽  
Inverse Response

Utilization of high austenitization temperatures to improve fracture toughness of UHSLA steels at similar strength levels has received considerable interest. However, these heat treatments result in reduced ductility and impact toughness. This inverse response of impact and plane strain fracture toughness is essentially due to microstructural effects and it is possible to achieve simultaneous improvements in all these properties through controlled variations in the microstructure.A vacuum remelted Si-modified 4340 steel was chosen for this study under three heat treated conditions, viz., conventional, high temperature and step with austenitization temperatures of 1143 K (1 hr), 1473 K (1 hr) and 1473 K (1 hr) furnace cooled to 1143 K (5 min), respectively. All samples were quenched in oil and tempered at 553 K (1 hr). A modified conventional heat treatment was also designed to achieve a desired microstructure with a 1143 K (1 hr) austenitization, a 923 K (1 hr) intermediate temper (after oil quenching), a 1123 K (3 min) reaustenitization and a final 553 K (1 hr) temper (after requenching) steps.

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.

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.

scholarly journals Heat Treatment and Austenitization Temperature Effect on Microstructure and Impact Toughness of an Ultra-High Strength Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 723
Author(s):  
Daniel M. Field ◽  
Stephen R. Cluff ◽  
Krista R. Limmer ◽  
Jonathan S. Montgomery ◽  
Daniel J. Magagnosc ◽  
...  
Keyword(s):  
Heat Treatment ◽  
High Strength ◽  
Impact Behavior ◽  
Austenitizing Temperature ◽  
Static Properties ◽  
Austenite Grain Size ◽  
Austenitization Temperature ◽  
Ultra High Strength Steel ◽  
Prior Austenite Grain Size ◽  
Strength And Ductility

Heat treatment parameters were varied to determine the effect of normalizing and austenitizing temperature on the properties of an ultra-high strength wrought steel. Normalizing temperature did not have a significant effect on strength and ductility. Higher normalizing temperatures led to an increase in final prior austenite grain size and a slight loss in toughness. Austenitizing temperature of 825 °C was insufficient to produce a fully austenitic structure prior to quenching and led to sub-par impact behavior. The best properties were obtained after austenitizing at 915 °C followed by water quenching; the resulting quasi static properties were shown to be a yield strength of 1380 MPa with an ultimate tensile strength of 1670 MPa and 12.5% total ductility. Charpy V-notch impact properties as high as 52 J at −40 °C and 75 J at 25 °C and the behavior were achieved using higher austenitizing temperatures as well.

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.

Homology Analysis of Prior Austenite Grain Size of SAE52100 Bearing Steel Processed by Cyclic Heat Treatment

2013 ◽  
Vol 813 ◽  
pp. 116-119 ◽  
Author(s):  
Kazuaki Nakane ◽  
Katsuyuki Kida ◽  
Koshiro Mizobe
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Retained Austenite ◽  
Prior Austenite ◽  
Cyclic Heat Treatment ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Cyclic Heat ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

Here, we introduce the mathematical methods to quantitatively evaluate the change of the tissue to quenching. SAE 52100 sample was repeatedly quenched and the influence of this cyclic heat treatment was investigated. The repeated quenching process increased the retained austenite content and had little influence on the materials hardness. The prior austenite grain size was decreased and consequently, refinement of the martensitic phase in the material occurred. The higher content of the retained austenite (higher fracture toughness) and the refinement of the microstructure accounted for the higher fatigue properties of the repeatedly quenched material. Here we use mathematical homology to quantify these features.

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 Hydrogen diffusion and trapping in laser additively manufactured ultra-high strength AerMet100 steel

CORROSION ◽  
10.5006/3812 ◽  
2021 ◽  
Author(s):  
Xian-zhe Ran ◽  
Dong Liu ◽  
Hai-bo Tang ◽  
Hua-ming Wang ◽  
Raymond Santucci ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Hydrogen Diffusion ◽  
High Strength ◽  
Trap States ◽  
Hydrogen Trapping ◽  
Tempered Martensite ◽  
Heat Treated ◽  
Martensite Microstructure ◽  
Effective Hydrogen ◽  
Similar Yield

Hydrogen trapping and the permeation behavior of laser additively manufactured (LAM) AerMet100 steel with an as-deposited specimen (AD) and after three types of heat-treated specimens (BM, TBMM, and TM) was investigated. At least three types of different hydrogen traps were identified in each microstructure of LAM AerMet100 steel, including both reversible and irreversible H traps. For as-deposited microstructure, the main reversible H trap states are related to the precipitation of M3C carbides associated with a detrapping activation energy (Ed) of 17.3±0.2 kJ/mol. After heat treatment, the dominant reversible hydrogen trap states in the tempered martensite microstructure have a different Ed value of 19.3±0.5 kJ/mol, which is attributed to the precipitation of highly coherent M2C carbides. In comparison with the reported Ed value of ~21.4 kJ/mol for main reversible hydrogen traps in wrought AerMet100 steel, the less Ed value in LAM AerMet100 steel is closely related to the composition change of M2C carbides. In all of the H pre-charged samples, the diffusible and total H concentration of the TM specimen and the TBMM specimen are about 3-4 times higher than that of the AD specimen and the BM specimen. The TM specimen with tempered martensite microstructure has the highest diffusible and total H concentration due to its high density of dominantly reversible H traps. The effective hydrogen diffusion coefficient (Deff) of LAM AerMet100 steel is on the order of 10-9 cm2/s, and decreases with increasing density of dominantly reversible H traps brought about by heat treatment. Furthermore, compared with wrought AerMet100 steel of a similar yield strength (~1750 MPa), the LAM AerMet100 steel has a comparable Deff of about 2.8×10-9 cm2/s.

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