Powder Metallurgically Produced Carbide Free Bainite

2014 ◽  
Vol 782 ◽  
pp. 480-486 ◽  
Author(s):  
Esa Vuorinen ◽  
Jesper Vang ◽  
Malo Carradot ◽  
Pernilla Johansson ◽  
Erik Navara
Keyword(s):  
Tensile Strength ◽  
Wear Resistance ◽  
Impact Toughness ◽  
Retained Austenite ◽  
Sliding Wear ◽  
Impact Testing ◽  
Powder Mixtures ◽  
Sintering Time ◽  
The Impact ◽  
Start Temperature

Steels with carbide free bainitic (CFB) microstructures show excellent strength, toughness and wear resistance. Cast or wrought products produced by conventional metallurgy have become gradually introduced in manufacturing of numerous machine components. The required silicon addition of more than 1.5wt% in CFB-steels limits the possibilities to produce components of these steels by P/M methods. The aim of this work has been to investigate the possibilites to produce CFB-steels by pressing and sintering. Four different powder mixtures based on Distaloy DC powder have been pressed to a relative density of 90 % and sintered in a N2-H2 atmosphere at 1150 °C. The sintered components were then austenitized followed by austempering at a temperature above the martensite start temperature. Tensile and impact testing together with microhardness measurements have been performed. The microstructures were studied by optical microscopy as well as SEM and XRD-methods. The tensile strength values achieved varied from 313 to 737 MPa, the elongation after fracture were between 0.1 and 0.2%. The impact toughness values varied between 4 and 11 J. The hardness of the bainite after short sintering time varied between 630 and 710 HV and the hardness of the CFB was 350 HV after short sintering time but reached 573 after prolonged sintering. The microstructure consisted mainly of bainite, small amount of CFB mixed with austenite but also of ferrite and retained austenite after short sintering time. A longer sintering time created a structure consiting of mainly CFB with bainite and a small amount of ferrite. The most interesting applications for P/M produced CFB-containing steels should be components subjected to sliding or rolling-sliding wear loads, as gears. The hardness and strenght values achieved in the present work indicate that P/M produced CFB-steels can prove superior to conventional P/M steels in many applications.

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 Evaluation of Microstructure and Impact Toughness of Shielded Metal Arc Dissimilar Weldments of High Strength Low Alloy Steel and Austenitic Stainless Steel

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Misbahu A Hayatu ◽  
Emmanuel T Dauda ◽  
Ola Aponbiede ◽  
Kamilu A Bello ◽  
Umma Abdullahi
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Impact Toughness ◽  
Impact Energy ◽  
High Strength ◽  
Impact Testing ◽  
Welding Parameters ◽  
Dissimilar Weld ◽  
Weld Joints ◽  
The Impact

There is a growing interest for novel materials of dissimilar metals due to higher requirements needed for some critical engineering applications. In this research, different dissimilar weld joints of high strength low alloy (HSLA) and 316 austenitic stainless steel grades were successfully produced using shielded metal arc welding (SMAW) process with 316L-16 and E7018 electrodes. Five variations of welding currents were employed within the specified range of each electrode. Other welding parameters such as heat inputs, welding speeds, weld sizes, arc voltages and time of welding were also varied. Specimens for different weld joint samples were subjected to microstructural studies using optical and scanning electron microscopes. The impact toughness test was also conducted on the samples using Izod impact testing machine. The analysis of the weld microstructures indicated the presence of type A and AF solidification patterns of austenitic stainless steels. The results further showed that the weld joints consolidated with E7018 electrode presented comparatively superior impact energy to the weldments fabricated by 316L-16 electrode. The optimum impact energy of E7018-weld joints (51J) was attained at higher welding heat inputs while that of 316L-16-weld joints (35J) was achieved at lower welding heat inputs, which are necessary requirements for the two electrodes used in the experiment. Hence, the dissimilar weld joints investigated could meet requirement for engineering application in offshore and other critical environments.Keywords—Dissimilar metal weld, heat input, impact toughness, microstructures

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.

scholarly journals Microstructure and Mechanical Properties of Tempered Ausrolled Nanobainite Steel

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 573
Author(s):  
Jing Zhao ◽  
Dezheng Liu ◽  
Yan Li ◽  
Yongsheng Yang ◽  
Tiansheng Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
Energy Yield ◽  
Partial Recovery ◽  
Fracture Appearance ◽  
The Impact

The microstructures and mechanical properties of ausrolled nanobainite steel, after being tempered at temperatures in the range of 200−400 °C, were investigated in this study. After being tempered, bainitic ferrite is coarsened and the volume fraction of retained austenite is reduced. The hardness and ultimate tensile strength decrease sharply. The impact energy, yield strength, and elongation increase with elevated tempered temperature at 200–300 °C but decrease with elevated tempered temperature when the samples are tempered at 350 °C and 400 °C. The fracture appearance of all the samples after impact tests is a brittle fracture. The variation of the mechanical properties may be due to partial recovery and recrystallization.

Effect of Re-Ti compound modification on the microstructure and mechanical properties of Cr12mov steel

2020 ◽  
pp. 002072091989756
Author(s):  
Sijing Fu ◽  
Binghua Jiang ◽  
Jing Wang ◽  
Hong Cheng
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Impact Toughness ◽  
Optical Microscope ◽  
Test Machine ◽  
Impact Tester ◽  
Near Net Shape ◽  
The Impact ◽  
Compound Modification ◽  
Ti Content

In this paper, near net shape casting technology was used to manufacture Cr12MoV steel die modified using RE-Ti. The samples with different RE(rare earth)-Ti content were fabricated by using the induction furnace. The microstructure of the samples was analyzed by using optical microscope and scanning electron microscope. Electronic universal tensile test machine, pendulum impact tester and rockwell apparatus were utilized to test the mechanical properties of the samples. The results show that after RE-Ti compound modification, the distribution and morphology of carbide are improved, and with the Ti increase, the impact toughness significantly increases, and tensile strength has a slight increase, but hardness is almost unchanged. When Ti content is 0.6%, the impact toughness and tensile strength are 14.9 J/cm2 and 634 MPa, respectively, reaching or approaching to the mechanical properties of the forged Cr12MoV steel.

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.

Effect of Grain Size and Meso-Texture on the Impact Toughness of Ti-Microalloyed Steel

2011 ◽  
Vol 702-703 ◽  
pp. 766-769 ◽  
Author(s):  
A. Ray ◽  
Debalay Chakrabarti
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Impact Toughness ◽  
Microalloyed Steel ◽  
Charpy Impact ◽  
Impact Testing ◽  
Grain Sizes ◽  
Matrix Strength ◽  
Charpy Impact Testing ◽  
The Impact

Charpy impact testing (over the transition temperature rage) on different samples of a Ti-microalloyed steel, having the same average-TiN particle size but different average-ferrite grain sizes, showed that in spite of the presence of large TiN cuboides, ferrite grain refinement can significantly improve the impact toughness, provided the meso-texture (i.e. the intensity of low-angle boundaries) and matrix strength can be restricted to low values.

The Effect of Pre-Strain and Strain Aging on Properties of X100 Line Pipe

2013 ◽  
Vol 690-693 ◽  
pp. 2270-2274
Author(s):  
Qiu Rong Ma ◽  
Hong Da Chen ◽  
Yan Hua Li ◽  
He Li
Keyword(s):  
Tensile Strength ◽  
Impact Toughness ◽  
Yield Strength ◽  
Tensile Properties ◽  
Aging Temperature ◽  
Strain Aging ◽  
Longitudinal Direction ◽  
Line Pipe ◽  
Toughness Test ◽  
The Impact

Tensile and impact toughness test on X100 line pipe with different pre-strain at different aging temperature were conducted to study the effect of pre-strain and aging temperature on properties of X100 line pipe. The result shows that yield strength and tensile strength of X100 line pipe would increase significantly with the introduction of pre-strain, while the impact toughness would decrease significantly. Effect of strain aging on tensile properties of X100 line pipe are more significantly. The yield strength, and tensile strength would increase significantly with the introduction of strain aging both transversal and longitudinal direction.

A Comparison of the Tribo-Mechanical Properties of a Wear Resistant Cobalt-Based Alloy Produced by Different Manufacturing Processes

2007 ◽  
Vol 129 (3) ◽  
pp. 586-594 ◽  
Author(s):  
H. Yu ◽  
R. Ahmed ◽  
H. de Villiers Lovelock
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Wear Mechanisms ◽  
Sliding Wear ◽  
Mechanical Performance ◽  
Cast Alloy ◽  
Processing Route ◽  
Structure Property ◽  
Wear Resistant ◽  
The Impact

This paper aims to compare the tribo-mechanical properties and structure–property relationships of a wear resistant cobalt-based alloy produced via two different manufacturing routes, namely sand casting and powder consolidation by hot isostatic pressing (HIPing). The alloy had a nominal wt % composition of Co–33Cr–17.5W–2.5C, which is similar to the composition of commercially available Stellite 20 alloy. The high tungsten and carbon contents provide resistance to severe abrasive and sliding wear. However, the coarse carbide structure of the cast alloy also gives rise to brittleness. Hence this research was conducted to comprehend if the carbide refinement and corresponding changes in the microstructure, caused by changing the processing route to HIPing, could provide additional merits in the tribo-mechanical performance of this alloy. The HIPed alloy possessed a much finer microstructure than the cast alloy. Both alloys had similar hardness, but the impact resistance of the HIPed alloy was an order of magnitude higher than the cast counterpart. Despite similar abrasive and sliding wear resistance of both alloys, their main wear mechanisms were different due to their different carbide morphologies. Brittle fracture of the carbides and ploughing of the matrix were the main wear mechanisms for the cast alloy, whereas ploughing and carbide pullout were the dominant wear mechanisms for the HIPed alloy. The HIPed alloy showed significant improvement in contact fatigue performance, indicating its superior impact and fatigue resistance without compromising the hardness and sliding∕abrasive wear resistance, which makes it suitable for relatively higher stress applications.

EFFECT OF HEAT TREATMENT ON (Cr, Fe)7C3/γ-Fe COATINGS IN SITU SYNTHESIZED BY VACUUM ELECTRON BEAM IRRADIATION

2017 ◽  
Vol 24 (Supp02) ◽  
pp. 1850028
Author(s):  
BINFENG LU ◽  
YUNXIA CHEN ◽  
MENGJIA XU
Keyword(s):  
Heat Treatment ◽  
Wear Resistance ◽  
Electron Beam ◽  
Impact Toughness ◽  
Composite Layer ◽  
Test Machine ◽  
Iron Matrix ◽  
Heat Treated ◽  
The Impact

(Cr, Fe)7C3/[Formula: see text]-Fe composite layer has been in situ synthesized on a low carbon steel surface by vacuum electron beam VEB irradiation. The synthesized samples were then subdued to different heat treatments to improve their impaired impact toughness. The microstructure, impact toughness and wear resistance of the heat-treated samples were studied by means of optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), microhardness tester, impact test machine and tribological tester. After heat treatment, the primary and eutectic carbides remained in their original shape and size, and a large number of secondary carbides precipitated in the iron matrix. Since the Widmanstatten ferrite in the heat affected zone (HAZ) transformed to fine ferrite completely, the impact toughness of the heat-treated samples increased significantly. The microhardness of the heat-treated samples decreased slightly due to the decreased chromium content in the iron matrix. The wear resistance of 1000[Formula: see text]C and 900[Formula: see text]C heat-treated samples was almost same with the as-synthesized sample. While the wear resistance of the 800[Formula: see text]C heat-treated one decreased slightly because part of the austenite matrix had transformed to ferrite matrix, which reduced the bonding of carbides particulates.

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