scholarly journals Improvement of Impact Toughness and Abrasion Resistance of a 3C-25Cr-0.5Mo Alloy Using a Design of Experiment Statistical Technique: Microstructural Correlations after Heat Treatments

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 595
Author(s):  
Alejandro González-Pociño ◽  
Juan Asensio-Lozano ◽  
Florentino Álvarez-Antolín ◽  
Ana García-Diez
Keyword(s):  
Wear Resistance ◽  
Impact Toughness ◽  
Abrasive Wear ◽  
Design Of Experiment ◽  
Retained Austenite ◽  
Statistical Technique ◽  
Cast Irons ◽  
Slow Cooling ◽  
Tempering Temperature ◽  
The Matrix

Hypoeutectic high chromium white cast irons are commonly used in the mining and cement industries, where high resistance to abrasive wear is demanded. Through the application of a Design of Experiment technique (DoE), different factors related to thermal industrial treatments are analysed with regard to resistance to abrasive wear and impact response. Abrasion tests were carried out in accordance with the ASTM G065-16 standard. The provisional results show that to increase wear resistance, high destabilisation temperatures (1050 °C) followed by slow cooling to room temperature (RT) and subsequent tempering at 400 °C are most favourable. This is because these conditions are favourable to maintaining a certain tetragonality of the martensite after tempering and also, because of the presence of a high density of mixed carbides M7C3, through a secondary precipitation during cooling. Oil quenching and a high tempering temperature (550 °C) with long dwell times of 6 h were found to increase impact toughness. These conditions favour a lack of retained austenite. The presence of retained austenite was found unfavourable for both wear resistance and toughness, whereas tempering at 400 °C has been shown to be insufficient to transform martensite on tempering, which in turn seemed to increase the hardness of the matrix constituent.

scholarly journals Influence of Thermal Parameters Related to Destabilization Treatments on Erosive Wear Resistance and Microstructural Variation of White Cast Iron Containing 18% Cr. Application of Design of Experiments and Rietveld Structural Analysis

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3252 ◽  
Author(s):  
Alejandro Gonzalez-Pociño ◽  
Florentino Alvarez-Antolin ◽  
Juan Asensio-Lozano
Keyword(s):  
Wear Resistance ◽  
Design Of Experiments ◽  
Retained Austenite ◽  
Erosive Wear ◽  
Structural Refinement ◽  
Cast Irons ◽  
Additional Increase ◽  
Eutectic Carbides ◽  
The Matrix ◽  
Key Factor

High-Cr hypo-eutectic white cast irons are used in very demanding environments that require high resistance to erosive wear. The influence on the microstructural variation and erosive wear resistance of several fundamental factors related to the thermal treatments of these cast irons was analysed by means of a fractional Design of Experiments (DoE). These factors included the ones related to the destabilization of austenite. The precipitated phases were identified by X-ray diffraction (XRD), while the Rietveld structural refinement method was used to determine their percentages by weight. Erosion wear resistance was calculated using the test defined by ASTM G76. It was concluded that the quench cooling medium does not significantly influence either erosive wear resistance or the proportion of martensite or retained austenite. The destabilization temperature is a key factor with respect to the percentage of retained austenite. In order to increase the amount of martensite and decrease the amount of retained austenite, temperatures not exceeding 1000 °C are required. An increase of 100 °C in the destabilization temperature can lead to a 25% increase in retained austenite. Moreover, tempering temperatures of around 500 °C favour an additional increase in the percentage of martensite. Erosive wear commences on the matrix constituent without initially affecting the eutectic carbides. Once the deterioration of the matrix constituent surrounding these carbides occurs, they are released. High tempering times provide an increase in resistance to erosive wear due to a second destabilization of austenite during the said tempering.

Structural Transformation of High Vanadium High Speed Steel during Tempering and its Influence on Abrasive Wear Performance of the Material

2009 ◽  
Vol 416 ◽  
pp. 443-448 ◽  
Author(s):  
Hui Min Chen ◽  
Liu Jie Xu ◽  
Shi Zhong Wei
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
Retained Austenite ◽  
High Speed ◽  
Testing Machine ◽  
High Speed Steel ◽  
Wear Test ◽  
Wear Testing ◽  
Tempering Temperature ◽  
Wear Performance

The expansion curves during the procedure of continuous cooling which high vanadium high speed steel (HSS) was tempered with 250°C, 550°C and 600°C after 1050°C quenching were determined by the Gleeble-1500D thermal simulation test device, and the curves were analyzed subsequently. The hardness and microstructure of high vanadium HSS under different tempering temperatures were analyzed by means of SEM, TEM and X-ray diffraction, and the influence of tempering temperature on the hardness and retained austenite were discussed. At the same time, the wear resistance of the material at different tempering temperatures was studied by the HST-100 friction wear testing machine, and the influence of microstructure on wear resistance was analyzed further. The studies show that the structures are not transformed at 250°C tempering with cooling rate of 0.5°C/s; The retained austenite transformed to martensite at about 390°C when 550°C and 600°C tempering. Wear test shows that the abrasive wear performance is excellent with 550°C tempering after 1050°C quenching because of the decrease of the amount of retained austenite, therefore the heat treatment of 550°C tempering after quenching of high vanadium HSS is optimal.

Effect of Microstructure and Mechanical Properties on Two Body Abrasive Wear Resistance of Medium-Carbon Low-Alloy Steel

2011 ◽  
Vol 52-54 ◽  
pp. 1247-1252 ◽  
Author(s):  
Jun Miao ◽  
Li Jun Wang ◽  
Chun Ming Liu
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Impact Toughness ◽  
Abrasive Wear ◽  
Alloy Steel ◽  
Water Quenching ◽  
Low Alloy Steel ◽  
Tempering Temperature ◽  
Medium Carbon ◽  
Test Steel

The effect of microstructure and mechanical properties on abrasion resistance of the medium-carbon low-alloy steel has been investigated under two body abrasive wear conditions. The results show that the microstructure of the test steel is mastenite and bainite/mastenite when the specimen subjected to water quenching and blow cooling respectively. The hardness of the test steel was over 52HRC when the specimen subjected to water quenching and blow cooling, however, effect of tempering temperature on hardness is slightly. The strength of the test steel is increased with the tempering temperature increased and the impact toughness change slightly under the blow cooling condition. The tensile strength of the test steel is decreased and the yield strength is increased with the tempering temperature increased when the specimen subjected to water quenching and followed tempering. The wear rate is increased with load and the wear mechanism is micro-cutting and microploughing. The wear resistance of bainite/martensite is better than single-phase martensite. The hardness and impact toughness are important factor under two body abrasive wear condition.

scholarly journals Erosive Wear Resistance Regarding Different Destabilization Heat Treatments of Austenite in High Chromium White Cast Iron, Alloyed with Mo

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 522 ◽  
Author(s):  
Alejandro Gonzalez-Pociño ◽  
Florentino Alvarez-Antolin ◽  
Juan Asensio-Lozano
Keyword(s):  
Wear Resistance ◽  
Retained Austenite ◽  
Erosive Wear ◽  
Sharp Decrease ◽  
Heat Treatments ◽  
Structural Refinement ◽  
Cast Irons ◽  
Eutectic Carbides ◽  
Secondary Carbides ◽  
The Matrix

With the aim of improving erosive wear resistance in hypoeutectic white cast irons with 18% Cr and 2% Mo, several samples of this grade were subjected to different heat treatments at 1000 °C to destabilize the austenite. The dwell times at this temperature varied from 4 to 24 h and the samples were cooled in air or oil. The existing phases were identified and quantified by applying the Rietveld structural refinement method. The results were correlated with the hardness of the material and with the microhardness of the matrix constituent. The greatest resistance to erosive wear was achieved in those samples that had a higher percentage of secondary carbides. The longer the dwell time at the destabilization temperature of austenite, the greater the amount of precipitated secondary carbides. However, the percentage of dissolved eutectic carbides is also higher. These eutectic carbides were formed as a result of non-equilibrium solidification. Low cooling rates (in still air) can offset this solution of eutectic carbides via the additional precipitation of secondary carbides in the 600–400 °C temperature range. A sharp decrease is observed in the percentage of retained austenite in those treatments with dwell times at 1000 °C equal to or greater than 12 h, reaching minimum values of around 2% volume. The percentage of retained austenite was always lower after oil quenching and the hardness of oil quenched samples was observed to be greater than those quenched in air. In these samples, the maximum hardness value obtained was 993 HV after a 12 h dwell, which result from the optimum balance between the percentages of retained austenite and of precipitated carbides.

scholarly journals INFLUENCE OF DEEP CRYOGENIC TREATMENT AT ABRASIVE WEAR RESISTANCE IN ASTM 743 CA6NM

2013 ◽  
Vol 12 (1) ◽  
pp. 25
Author(s):  
A. F. Hernandez ◽  
C. R. M. Silva ◽  
J. A. Araujo ◽  
J. D. B. De Mello
Keyword(s):  
Wear Resistance ◽  
Abrasive Wear ◽  
Retained Austenite ◽  
Cryogenic Treatment ◽  
Lath Martensite ◽  
Wear Test ◽  
Abrasive Wear Resistance ◽  
Deep Cryogenic Treatment ◽  
Conventional Heat Treatment ◽  
The Matrix

The Deep Cryogenic Treatment (DCT) has been used for improvement of steel mechanical properties, basically the abrasive wear resistance. At this work the cryogenic treatment at -190oC for 20 hours was applied, after conventional heat treatment, to improve its abrasive wear resistance. The specimens, divided in two groups, had been austenitized for forty five minutes at 965oC and 1065oC, respectively, then quenched in oil at room temperature. Afterwards they were tempered at 565oC for 90 minutes, and then cooled in air. Subsequently some samples were treated cryogenically, and some of them were submitted to a new cycle of tempering at 565oC for 90 minutes. The performed experiment included: hardness brinell, Xraydifratometry, metallography and micro-abrasive wear test. Variations in the microstructure with an improvement in the abrasive wear coefficient were found. These variations are probably a positive effect of the DCT on the samples microstructure. The microstructure were transformed from blocks of parallel lath martensite to small parallel or almost parallel packages of fine needles forming austenite. Traces of previous or retained austenite were found delimiting the grains. It is presumed that micro-carbide homogeneously distributed in the matrix and in the grain´s contours of the retained austenite was formed.

Modelling of phase transformations and hardening of carbonitrided steels

2004 ◽  
Vol 120 ◽  
pp. 129-136
Author(s):  
M. Przyłęcka ◽  
W. Gęstwa ◽  
G. E. Totten
Keyword(s):  
Wear Resistance ◽  
Phase Composition ◽  
Abrasive Wear ◽  
Phase Transformations ◽  
Thermal Processing ◽  
Retained Austenite ◽  
Abrasive Wear Resistance ◽  
Processing Conditions ◽  
The Impact

There are a variety of opinions regarding the influence of retained austenite and carbides on the properties exhibited by carbonitrided steels. In this paper, the development of a model marking relationship between phase composition, and properties of hardened carbonitrided steel has been presented. A summary of the impact of structure on properties is provided in Table 1. In the study reported here, the impact of thermal processing conditions on retained austenite and carbides was examined for carbonitrided and hardened 20 (C22), 20H (20Cr4), 15HN (17CrNi6-6) and 16HG (16MnCr5) steels. The models that are reported were experimentally validated. In particular, the results obtained for structure with respect to hardness and abrasive wear resistance were discussed for carbonitrided and hardened 20H (20Cr4) steel.

Development of Carbidic Austempered Ductile Iron (CADI)

2020 ◽  
Vol 835 ◽  
pp. 163-170
Author(s):  
Hayam A. Aly ◽  
Adel Nofal ◽  
Abdel Hamid A. Hussein ◽  
Elsayed M. El-Banna
Keyword(s):  
Wear Resistance ◽  
Impact Toughness ◽  
Ductile Iron ◽  
Abrasion Resistance ◽  
Austempered Ductile Iron ◽  
Image Analyzer ◽  
X Ray Diffraction ◽  
Individual Factor ◽  
Tempering Temperature ◽  
Combined Action

This study aimed at optimizing impact toughness and high wear resistant carbidic austempered ductile iron (CADI) by controlling the morphology, size and quantity of carbides. The effects of dynamic solidification, niobium addition, combined action of them and heat treatment have been investigated. Investigations were performed by means of the image analyzer, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffraction. Impact toughness, hardness and abrasion wear resistance tests were conducted. Fracture surfaces were studied. Results indicated that microstructural control during solidification is the most valuable tool to attain the optimum combination between impact toughness and wear resistance in CADI. Combined action of Nb addition and dynamic solidification improves impact toughness, hardness and wear resistance even more than the action of each individual factor. In the as-cast condition, impact toughness, hardness and abrasion resistance were improved after dynamic solidification compared to statically solidify one by 31.2%, 18.75% and 87.96% respectively. This enhancement was increased to 36.9%, 25.93% and 128. % by adding 1% Nb. Lower tempering temperature of 275°C exhibit best hardness and abrasion resistance better than higher tempering temperature of 375°C.

scholarly journals The Effect of Tempering on the Microstructure and Mechanical Properties of a Novel 0.4C Press-Hardening Steel

2019 ◽  
Vol 9 (20) ◽  
pp. 4231
Author(s):  
Oskari Haiko ◽  
Antti Kaijalainen ◽  
Sakari Pallaspuro ◽  
Jaakko Hannula ◽  
David Porter ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Low Temperature ◽  
Impact Toughness ◽  
Retained Austenite ◽  
Hot Strip Mill ◽  
Tempering Temperature ◽  
Press Hardening ◽  
Dislocation Densities ◽  
The Impact

In this paper, the effects of different tempering temperatures on a recently developed ultrahigh-strength steel with 0.4 wt.% carbon content were studied. The steel is designed to be used in press-hardening for different wear applications, which require high surface hardness (650 HV/58 HRC). Hot-rolled steel sheet from a hot strip mill was austenitized, water quenched and subjected to 2-h tempering at different temperatures ranging from 150 °C to 400 °C. Mechanical properties, microstructure, dislocation densities, and fracture surfaces of the steels were characterized. Tensile strength greater than 2200 MPa and hardness above 650 HV/58 HRC were measured for the as-quenched variant. Tempering decreased the tensile strength and hardness, but yield strength increased with low-temperature tempering (150 °C and 200 °C). Charpy-V impact toughness improved with low-temperature tempering, but tempered martensite embrittlement at 300 °C and 400 °C decreased the impact toughness at −40 °C. Dislocation densities as estimated using X-ray diffraction showed a linear decrease with increasing tempering temperature. Retained austenite was present in the water quenched and low-temperature tempered samples, but no retained austenite was found in samples subjected to tempering at 300 °C or higher. The substantial changes in the microstructure of the steels caused by the tempering are discussed.

scholarly journals Effect of Tempering Temperature on Microstructures and Wear Behavior of a 500 HB Grade Wear-Resistant Steel

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 45 ◽  
Author(s):  
Erding Wen ◽  
Renbo Song ◽  
Wenming Xiong
Keyword(s):  
Electron Microscopy ◽  
Wear Resistance ◽  
Impact Toughness ◽  
Wear Behavior ◽  
Temper Embrittlement ◽  
Surface Hardness ◽  
Resistant Steel ◽  
Tempering Temperature ◽  
Wear Resistant ◽  
The Impact

The microstructure and wear behavior of a 500 Brinell hardness (HB) grade wear-resistant steel tempered at different temperatures were investigated in this study. The tempering microstructures and wear surface morphologies were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The relationship between mechanical properties and wear resistance was analyzed. The microstructure of the steel mainly consisted of tempered martensite and ferrite. Tempered troosite was obtained when the tempering temperature was over 280 °C. The hardness decreased constantly with the increase of tempering temperature. The same hardness was obtained when tempered at 260 °C and 300 °C, due to the interaction of Fe3C carbides and dislocations. The impact toughness increased first and reached a peak value when tempered at 260 °C. As the tempering temperature was over 260 °C, carbide precipitation would occur along the grain boundaries, which led to temper embrittlement. The best wear resistance was obtained when tempered at 200 °C. At the initiation of the wear test, surface hardness was considered to be the dominant influencing factor on wear resistance. The effect of surface hardness improvement on wear resistance was far greater than the impact toughness. With the wear time extending, the crushed quartz sand particles and the cut-down burs would be new abrasive particles which would cause further wear. Otherwise, the increasing contact temperature would soften the matrix and the adhesive wear turned out to be the dominant wear mechanism, which would result in severe wear.

Microstructure and Heat Treatment of Hot Work Tool Steel: Influence on Mechanical Properties and Wear Behaviour

2018 ◽  
Vol 767 ◽  
pp. 196-203 ◽  
Author(s):  
Božo Skela ◽  
Marko Sedlaček ◽  
Bojan Podgornik
Keyword(s):  
Tensile Strength ◽  
Impact Toughness ◽  
Abrasive Wear ◽  
Tool Steel ◽  
Wear Behaviour ◽  
Wear Properties ◽  
Tempering Temperature ◽  
Hot Work Tool Steel ◽  
Heat Treated ◽  
Wear Tests

Good mechanical and wear properties of hot-work tool steels are needed for tools to withstand severe service conditions during their operational lifetime. Thus, the aim of this investigation was to correlate mechanical and wear properties with changes in microstructure of commercially available hot work tool steel Sitherm S361R. Hardness, impact toughness, tensile strength and wear tests were performed. Hot-work tool steel was heat treated at austenitizing temperature 1030 °C for 15 min in a horizontal vacuum furnace and gas quenched using nitrogen. One set of samples was investigated in as quenched state. Double tempering of samples was performed after quenching for 2 h at each of chosen temperatures, with first tempering temperature of 500 °C for the whole set of tempered samples. The second tempering was conducted at temperatures from 520 °C to 640 °C with increment of 30 °C for each set of samples. Microstructure of differently heat treated samples showed martensitic matrix, but different fraction and distribution of carbides, consequently influencing hardness, impact toughness, tensile strength, yield strength and wear resistance. Reciprocating sliding wear tests were carried out at room temperature in order to correlate microstructure of differently heat treated hot-work tool steel with wear. In order to achieve adhesive and abrasive wear mechanisms, 100Cr6 and Al2O3 balls were used as counter-body, respectively. Combination of adhesive and abrasive wear was observed for all specimens with different hardness when using 100Cr6 material as a counter body. However, in the case of Al2O3 abrasive wear was found as the prevailing wear mechanism.

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