Applying the Masteralloy Concept for Manufacturing of Sinter Hardening PM Steel Grades

2021 ◽  
Vol 42 ◽  
pp. 17-23
Author(s):  
Stefan Geroldinger ◽  
Raquel de Oro Calderon ◽  
Christian Gierl-Mayer ◽  
Herbert Danninger
Keyword(s):  
Heat Treating ◽  
Processing Route ◽  
Cooling Rates ◽  
Base Powder ◽  
Martensitic Microstructure ◽  
Special Alloy ◽  
Steel Grades ◽  
Gas Quenching ◽  
One Step ◽  
Cct Diagrams

Sinter hardening is a powder metallurgy processing route that combines the sintering and the heat treating processes in one step by gas quenching the components immediately after they have left the high temperature zone of the furnace. It is both economically attractive and ecologically beneficial since it renders deoiling processes unnecessary. The slower cooling rates associated with gas compared to oil quenching however requires special alloy concepts different to those known from wrought steels. In the present study it is shown that by admixing atomized masteralloy powders consisting of suitable combinations of Mn, Cr, Si, Fe and C to base iron or pre-alloyed steel powders, sinter hardening PM steel grades can be produced that transform to martensitic microstructure at cooling rates of 2-3 K/s as typical for industrial sinter hardening. This is confirmed by CCT diagrams and hardness measurements. However, metallographic investigations are also necessary because in sintered steels, the cores of the largest base powder particles are alloyed very slowly during sintering and therefore tend to result in soft spots in the sinter hardened microstructure which are mostly not discernible in the CCT diagrams. Here, even slight pre-alloying of the base powder with Mo and/or Cr is helpful, both increasing the hardenability of the steels compared to base plain iron and avoiding soft spots in the microstructure.

scholarly journals High Pressure Gas Quenching Evolution

2019 ◽  
Author(s):  
Dennis Beauchesne
Keyword(s):  
High Pressure ◽  
Heat Treating ◽  
Carbon Steels ◽  
Cooling Rates ◽  
Single Chamber ◽  
Heat Treat ◽  
Automotive Transmission ◽  
Gas Quenching

Abstract Gas quenching has been involved in heat treating for many years. Over those years, the technology has been looked at by many who heat treat to be limited to single chamber furnaces, which would standardly be 2, 6, 10 and 12 bar systems with varying methods of introducing the gas through the load. High pressure gas quenching has evolved tremendously to produce quenching with gas to provide properly hardened carbon steels for many applications including most automotive transmission products today. We will show that the technology used in high pressure gas quenching has improved and how the amount and method of cooling has evolved. Along with using new steels with higher hardenability, we will look at the evolution of high pressure gas quenching in heat treating and the systems available today with data from different loads at various cooling rates.

Comparing fast inductive tempering and conventional tempering: Effects on microstructure and mechanical properties

2018 ◽  
Vol 115 (4) ◽  
pp. 407 ◽  
Author(s):  
Annika Eggbauer Vieweg ◽  
Gerald Ressel ◽  
Peter Raninger ◽  
Petri Prevedel ◽  
Stefan Marsoner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Impact Energy ◽  
Charpy Impact ◽  
Heat Treating ◽  
Processing Route ◽  
High Heating Rate ◽  
Heating Rates ◽  
High Heating ◽  
Tempering Treatment ◽  
Carbide Distribution

Induction heating processes are of rising interest within the heat treating industry. Using inductive tempering, a lot of production time can be saved compared to a conventional tempering treatment. However, it is not completely understood how fast inductive processes influence the quenched and tempered microstructure and the corresponding mechanical properties. The aim of this work is to highlight differences between inductive and conventional tempering processes and to suggest a possible processing route which results in optimized microstructures, as well as desirable mechanical properties. Therefore, the present work evaluates the influencing factors of high heating rates to tempering temperatures on the microstructure as well as hardness and Charpy impact energy. To this end, after quenching a 50CrMo4 steel three different induction tempering processes are carried out and the resulting properties are subsequently compared to a conventional tempering process. The results indicate that notch impact energy raises with increasing heating rates to tempering when realizing the same hardness of the samples. The positive effect of high heating rate on toughness is traced back to smaller carbide sizes, as well as smaller carbide spacing and more uniform carbide distribution over the sample.

NITRALLOY 125

Alloy Digest ◽  
1957 ◽  
Vol 6 (9) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Alloy Steel ◽  
Low Temperatures ◽  
Heat Treating ◽  
Ammonia Gas ◽  
Steel Mills ◽  
Special Alloy

Abstract NITRALLOY 125 (0.20-0.30% C) is a special alloy steel which can be nitrided, that is, surface hardened, without final quenching, by the action of ammonia gas at relatively low temperatures. Nitralloy 125 is also known as Nitralloy H. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-61. Producer or source: Alloy steel mills and foundries.

NITRALLOY N

Alloy Digest ◽  
1956 ◽  
Vol 5 (3) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Alloy Steel ◽  
Low Temperatures ◽  
Heat Treating ◽  
Appreciable Amount ◽  
Dispersion Hardening ◽  
Ammonia Gas ◽  
Steel Mills ◽  
Special Alloy

Abstract NITRALLOY N is a special alloy steel which can be nitrided, that is, surface hardened, without final quenching, by the action of ammonia gas at relatively low temperatures. The presence of an appreciable amount of nickel in Nitralloy N both strengthens and toughens the case and develops dispersion hardening in rhe core during nitriding. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-39. Producer or source: Alloy steel mills and foundries.

Effect of boron on the continuous cooling transformation kinetics in a low carbon advanced ultra-high strength steel (A-UHSS)

2012 ◽  
Vol 1485 ◽  
pp. 83-88 ◽  
Author(s):  
G. Altamirano ◽  
I. Mejía ◽  
A. Hernández-Expósito ◽  
J. M. Cabrera
Keyword(s):  
Research Work ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructural Characterization ◽  
Low Carbon ◽  
Transformation Kinetics ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Cct Diagrams

ABSTRACTThe aim of the present research work is to investigate the influence of B addition on the phase transformation kinetics under continuous cooling conditions. In order to perform this study, the behavior of two low carbon advanced ultra-high strength steels (A-UHSS) is analyzed during dilatometry tests over the cooling rate range of 0.1-200°C/s. The start and finish points of the austenite transformation are identified from the dilatation curves and then the continuous cooling transformation (CCT) diagrams are constructed. These diagrams are verified by microstructural characterization and Vickers micro-hardness. In general, results revealed that for slower cooling rates (0.1-0.5 °C/s) the present phases are mainly ferritic-pearlitic (F+P) structures. By contrast, a mixture of bainitic-martensitic structures predominates at higher cooling rates (50-200°C/s). On the other hand, CCT diagrams show that B addition delays the decomposition kinetics of austenite to ferrite, thereby promoting the formation of bainitic-martensitic structures. In the case of B microalloyed steel, the CCT curve is displaced to the right, increasing the hardenability. These results are associated with the ability of B atoms to segregate towards austenitic grain boundaries, which reduce the preferential sites for nucleation and development of F+P structures.

scholarly journals Effect of Intercritical Annealing and Austempering on the Microstructure and Mechanical Properties of a High Silicon Manganese Steel

Metals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1448 ◽  
Author(s):  
Mattia Franceschi ◽  
Luca Pezzato ◽  
Claudio Gennari ◽  
Alberto Fabrizi ◽  
Marina Polyakova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Intercritical Annealing ◽  
High Strength ◽  
Xrd Analysis ◽  
Tensile Tests ◽  
Manganese Steel ◽  
Microstructure And Mechanical Properties ◽  
Martensitic Microstructure ◽  
Steel Grades ◽  
High Silicon

High Silicon Austempered steels (AHSS) are materials of great interest due to their excellent combination of high strength, ductility, toughness, and limited costs. These steel grades are characterized by a microstructure consisting of ferrite and bainite, accompanied by a high quantity retained austenite (RA). The aim of this study is to analyze the effect of an innovative heat treatment, consisting of intercritical annealing at 780 °C and austempering at 400 °C for 30 min, on the microstructure and mechanical properties of a novel high silicon steel (0.43C-3.26Si-2.72Mn wt.%). The microstructure was characterized by optical and electron microscopy and XRD analysis. Hardness and tensile tests were performed. A multiphase ferritic-martensitic microstructure was obtained. A hardness of 426 HV and a tensile strength of 1650 MPa were measured, with an elongation of 4.5%. The results were compared with those ones obtained with annealing and Q&T treatments.

scholarly journals The Phase Transformations in Hypoeutectoid Steels Mn-Cr-Ni

2015 ◽  
Vol 60 (1) ◽  
pp. 497-502 ◽  
Author(s):  
E. RoŻniata ◽  
R. Dziurka
Keyword(s):  
Chemical Composition ◽  
Phase Transformations ◽  
Critical Points ◽  
Light Microscope ◽  
Cooling Curves ◽  
Critical Temperatures ◽  
Martensitic Microstructure ◽  
Cct Diagrams ◽  
Kinetics Of ◽  
Undercooled Austenite

Abstract The results of a microstructure and hardness investigations of the hypoeutectoid steels Mn-Cr-Ni, imitating by its chemical composition toughening steels, are presented in the paper. The analysis of the kinetics of phase transformations of undercooled austenite of steels containing different amounts of alloying elements in their chemical composition, constitutes the aim of investigations. Metallographic examinations were carried out on a Axiovert 200 MAT light microscope. Sections were etched with a 3% HNO3 solution in C2H5OH. Dilatometric tests were performed using L78 R.I.T.A dilatometer. Using dilatometer the changes of elongation (Δl) of the samples with dimensions Ø 3×10 mm as a function of temperature (T) were registered. Obtained heating curves were used to precisely determine the critical temperatures (critical points) for the tested steels, while the differentiation of obtained cooling curves allowed to precisely define the temperatures of the beginning and the end of particular transition to draw CCT diagrams. Four CCT diagrams worked out for the tested hypoeutectoid steels (for quenching of steel) are - in the majority of steels - separated by the undercooled austenitic range and are of the letter „C” shape. However, for steels with Mn and Ni the separation of diffusive transformations from the bainitic transformation by the stable austenitic range is not observed. Hardenability of four investigated hypoeutectoid steels is similar, but still not high. To obtain martensite in the microstructure of these steels, it is necessary to apply the cooling rate higher than 25°C/s. The exception constitutes the Mn - Ni steel, in which only cooling with the rate higher than 50°C/s allows to achieve the martensitic microstructure and to avoid diffusive transformations (pearlitic and ferritic).

The Role of Continuous Cooling Transformation Diagrams in Material Design for High Strength Oil and Gas Transmission Pipeline Steels

2006 ◽  
Author(s):  
Douglas G. Stalheim ◽  
Govindarajan Muralidharan
Keyword(s):  
Oil And Gas ◽  
Alloy Composition ◽  
Processing Route ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Effective Manner ◽  
Final Microstructure ◽  
Cct Diagrams ◽  
Transmission Pipelines

The economical, environmental, and safe movement of gas and oil to the marketplace requires transmission pipelines to be designed to operate at higher pressures and/or with improved toughness over a variety of temperature ranges. To meet the higher strength and toughness specification requirements of these transmission pipelines, appropriate materials and processes must be used in their design and construction. This includes selection of appropriate alloy composition, processing routes, microstructure control, and cost. A continuous cooling transformation (CCT) diagram is a tool that can be used to select alloy composition and processing route in order to obtain a specific, desirable microstructure for transmission linepipe steels in a cost-effective manner. In the past, CCT diagrams were developed experimentally under laboratory conditions, thus requiring extensive time and effort. However, with the vast data available and improved computational tools, reasonably accurate computer generated CCT diagrams can be produced quickly. These computer generated diagrams can give the materials design engineer a reasonable understanding of the effect of subjecting a given alloy to various processing routes and hence the resultant microstructures. Since final microstructure is a key variable in determining the linepipe steel material properties, the chosen alloy/processing route and its effect on the final microstructure needs to be understood. This paper will discuss the role of CCT diagrams in the design of steels (cost, alloy, processing, and microstructure) for oil and gas transmission pipelines. Examples of computer generated CCT digrams for various API alloy designs are included.

Effects of Vanadium on the Continuous Cooling Transformation of 0.7 %C Steel for Railway Wheels

2016 ◽  
Vol 367 ◽  
pp. 60-67 ◽  
Author(s):  
Solange T. Fonseca ◽  
Amilton Sinatora ◽  
Antonio J. Ramirez ◽  
Domingos J. Minicucci ◽  
Conrado R. Afonso ◽  
...  
Keyword(s):  
Room Temperature ◽  
Initial Temperature ◽  
Volume Fraction ◽  
Martensite Formation ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Xrd Techniques ◽  
Railway Wheels ◽  
Cct Diagrams

To understand the effect of vanadium on the austenite decomposition of a 0.7 %C steel used in railway wheels the Continuous Cooling Transformation (CCT) diagrams were obtained and the microstructures analyzed with optical, SEM, TEM and XRD techniques. Vanadium refined the austenitic grain (12 and 6 μm for 7C and 7V, respectively), what can be explain by the presence of fine (10 nm in diameter) V4C3 precipitates, which restricts the austenitic grain growth. In addition, vanadium, in solid solution, reduced the pearlite interlamelar spacing (0.13 and 0.11 μm for 7C and 7V, respectively) by depressing the initial temperature pearlite formation (644 and 639 °C for 7C and 7V, respectively). He increased the ferrite volume fraction from 1 to 3 % at cooling rate of 1 oC/s, due the fact that vanadium is a ferrite stabilizer. Vanadium addition did not affect the initial temperature for martensite formation, but increased the hardenability with martensite formation at slower cooling rates (10 and 5 oC/s for 7C and 7V, respectively). For higher cooling rates (20 to 100 oC/s), the austenite transformation to martensite at room temperature was incomplete and all steels presented martensite and retained austenite, which volumetric fraction was near the same for both steels varying from 20 to 40 %.

NITRALLOY EZ

Alloy Digest ◽  
1956 ◽  
Vol 5 (12) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
Alloy Steel ◽  
Low Temperatures ◽  
Heat Treating ◽  
Ammonia Gas ◽  
Steel Mills ◽  
Special Alloy

Abstract NITRALLOY EZ is a special alloy steel which can be nitrided, that is, surface hardened, without final quenching, by the action of ammonia gas at relatively low temperatures. It is the free-cutting grade of the nitriding steels. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-51. Producer or source: Alloy steel mills and foundries.

Sign in / Sign up

Export Citation Format

Share Document