scholarly journals Reaction of Unalloyed and Cr-Mo Alloyed Steels with Nitrogen from the Sintering Atmosphere

2016 ◽  
Vol 16 (2) ◽  
pp. 86-98
Author(s):  
Magdalena Dlapka ◽  
Christian Gierl-Mayer ◽  
Raquel de Oro Calderon ◽  
Herbert Danninger ◽  
Sven Bengtsson ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Critical Temperature ◽  
Structural Steels ◽  
Low Alloy Steel ◽  
Alloying Element ◽  
Sintering Atmosphere ◽  
High Affinity ◽  
Different Temperatures ◽  
Steel Grades ◽  
The Subject

Abstract Nitrogen is usually regarded as an inert sintering atmosphere for PM steels; however, this cannot be taken for granted in particular for steels alloyed with nitride forming elements. Among those elements, chromium has become more and more important as an alloying element in sintered low alloy structural steels in the last decade due to the moderate alloying cost and the excellent mechanical properties obtainable, in particular when sinter hardening is applied. The high affinity of Cr to oxygen and the possible ways to overcome related problems have been the subject of numerous studies, while the fact that chromium is also a fairly strong nitride forming element has largely been neglected at least for low alloy steel grades, although frequently used materials like steels from Cr and Cr-Mo prealloyed powders are commonly sintered in atmospheres consisting mainly of nitrogen. In the present study, nitrogen pickup during sintering at different temperatures and for varying times has been studied for Cr-Mo prealloyed steel grades as well as for unalloyed carbon steel. Also the effect of the cooling rate and its influence on the properties, of the microstructure and the composition have been investigated. It showed that the main nitrogen uptake occurs not during isothermal sintering but rather during cooling. It could be demonstrated that a critical temperature range exists within which the investigated CrM-based steel is particularly sensitive to nitrogen pickup.

scholarly journals Sintered Structural Steels Containing Mn, Cr And Mo – The Summary of the Investigations

2016 ◽  
Vol 16 (2) ◽  
pp. 59-85
Author(s):  
Maciej Sulowski
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Sintered Material ◽  
Structural Steels ◽  
Processing Conditions ◽  
Alloying Element ◽  
Sintering Atmosphere ◽  
Sintered Steels ◽  
Method Of Production ◽  
Better Than

AbstractThe paper is presented the development and method of production of modern, Ni-free sintered structural steels which contain carbide forming alloying elements (Cr) with high affinity for oxygen (Cr, Mn) and the much smaller additive of an expensive alloying element (Mo), enabling the production of structural sintered steels in commercial belt furnaces, using safe sintering atmospheres. The investigations reported deal with the analysis of microstructure and mechanical properties of these sintered structural steels produced in different processing conditions, especially modification of chemical composition of sintering atmosphere and also the connections between the microstructure of sintered material and its mechanical properties. This analysis was done to propose the appropriate chemical composition of sintered Ni-free steels with properties which are comparable or even better than those of sintered structural steels containing rich and carcinogenic nickel. The investigations of PM Mn- Cr-Mo steels were preceded by those on Mn steels.

scholarly journals A novel method of sintering hybrid steels in an improved semiclosed container system

2013 ◽  
Vol 45 (3) ◽  
pp. 379-383 ◽  
Author(s):  
A. Cias
Keyword(s):  
Mechanical Properties ◽  
Structural Steels ◽  
Laboratory Scale ◽  
The Other ◽  
Reduction Reactions ◽  
High Affinity ◽  
Conventional Sintering ◽  
Superior Mechanical Properties ◽  
Novel Method

Conventional sintering techniques for structural steels have been developed principally for Cu and Ni containing alloys. Applying these to Cr and Mn steels (successful products of traditional metallurgy) encounter the problem of the high affinity for oxygen of these elements. A solution is employing a microatmosphere in a semiclosed container which favours reduction reactions. This has already proved successful on a laboratory scale, especially with nitrogen as the furnace gas. Further modifications to the system, now described, include the use of two sintering boxes, one inside the other. Superior mechanical properties, even using air as the furnace gas, are attainable.

Three Generations Micro-Allying Steel Processing: Thirty Years of Successive Work at CMRDI

2020 ◽  
Vol 835 ◽  
pp. 324-334
Author(s):  
Maha El-Meligy ◽  
Taher El-Bitar
Keyword(s):  
Mechanical Properties ◽  
Temper Embrittlement ◽  
Steel Plates ◽  
Alloying Elements ◽  
Recrystallization Temperature ◽  
Low Carbon ◽  
Alloying Element ◽  
Hot Strip ◽  
Steel Processing ◽  
Steel Grades

The present article presents cumulative works, which were carried out in the field of micro-alloying steel processing at Central Metallurgical R&D Institute (CMRDI) and/or full scale trials in collaboration with the Egyptian steel industry.It was agreed upon defining three main generations of processing micro-alloying steel. The 1stgeneration starts officially on 1975 and continues up to 1995, where it deals with using Ti and V as micro-alloying elements for steel long products. On the year 1985, Central Metallurgical R&D Institute (CMRDI) succeeded to implement of HSLA V-micro-alloyed rebar steel grades at Delta steel mills instead of conventional rebar grades.The 2nd generation was starting on late 1995 and continued to 2005. It was dealing mainly with low carbon content steel (0.04-0.08 %) for flat products (plate and sheet). The most successfully used micro-alloying element was Nb. Beside its precipitate forming effect, Nb is working as substitution solid solution strengthener. Moreover, it raises the recrystallization temperature (Tr). Mainly, micro-alloyed flat steels were developed to fulfill the requirements of the American Petroleum Institute (API) specifications 5L- Product Specification Levels (PSL1) and (PSL2) for manufacturing oil and natural gas pipelines. Meanwhile, a newly born Compact Slab Processing (CSP)-hot strip direct rolling technology was created. On years 2002, the metal forming department in CMRDI succeeded to implement controlled rolling of hot strip Nb-steel sheet at the Compact Slab Process (CSP) Machine in Alexandria National Iron and Steel (ANSDK) Company. Controlled hot rolling schedules were used and followed by early and late cooling at the run out table (ROT). Both contracts were fruitfully succeeded to introduce the API X52 grade at ANSDK Company, followed by X60, and X70 steel grades at Ezz Flat Steel (EFS) Company. The essential mechanical properties of the processed API steel sheets were matched with the API 5L-PSL2 specifications.The 3rd generation was initially developed after 2005 and continued up to day. It deals with micro-alloying with special functional elements like Boron (B). Boron was favored as a micro-alloying element for bilateral effects. Boron carbide (B4C) precipitates are the hardest after diamond, which would be reflected on raising the mechanical properties of the steel. Moreover, Boron was favorably used because it delays the temper embrittlement phenomena. On year 2014, the National for Military Industrialization authority requested from CMRDI to collaborate with Military Factory 100 to develop a technology package for processing armor steel plates. Trials were started with a 3rd generation B-micro-alloyed steel alloy. Many other alloying elements were used beside Boron to develop extra high strength 6.0 mm thickness plates. Finish hot rolled plates were then subjected to a subsequent water quenching from 900 °C and followed by tempering at 250 °C for 20 min. Representation 50X50 cm2 steel plates were successfully passed after 3 bullets in front and 3 bullets rear shooting.

scholarly journals The Influence of Nickel and Tin Additives on the Microstructural and Mechanical Properties of Al-Zn-Mg-Cu Alloys

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Haider T. Naeem ◽  
Kahtan S. Mohammed ◽  
Khairel R. Ahmad ◽  
Azmi Rahmat
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloys ◽  
Base Alloy ◽  
Copper Alloys ◽  
Aging Treatment ◽  
Alloying Element ◽  
Cu Alloys ◽  
Different Temperatures ◽  
Retrogression And Reaging ◽  
Better Than

The effects of nickel and nickel combined tin additions on mechanical properties and microstructural evolutions of aluminum-zinc-magnesium-copper alloys were investigated. Aluminum alloys containing Ni and Sn additives were homogenized at different temperatures conditions and then aged at 120°C for 24 h (T6) and retrogressed at 180°C for 30 min and then reaged at 120°C for 24 h (RRA). Comparison of the ultimate tensile strength (UTS) of as-quenched Al-Zn-Mg-Cu-Ni and Al-Zn-Mg-Cu-Ni-Sn alloys with that of similar alloys which underwent aging treatment at T6 temper showed that gains in tensile strengths by 385 MPa and 370 MPa were attained, respectively. These improvements are attributed to the precipitation hardening effects of the alloying element within the base alloy and the formation of nickel/tin-rich dispersoid compounds. These intermetallic compounds retard the grain growth, lead to grain refinement, and result in further strengthening effects. The outcomes of the retrogression and reaging processes which were carried on aluminum alloys indicate that the mechanical strength and Vickers hardness have been enhanced much better than under the aging at T6 temper.

Review on the mechanical properties and biocompatibility of titanium implant: The role of niobium alloying element

2021 ◽  
Vol 112 (6) ◽  
pp. 505-513
Author(s):  
Ahmad Farrahnoor ◽  
Hussain Zuhailawati
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloys ◽  
Elastic Moduli ◽  
Stress Shielding ◽  
Titanium Implant ◽  
Implant Loosening ◽  
Alloying Element ◽  
Different Temperatures ◽  
Low Modulus

Abstract Biomedical titanium alloys with elastic moduli close to that of cortical bone have gained great attention in the field of bone implantation. A low modulus is desirable in an implant to prevent stress shielding, which usually leads to critical clinical issues, such as bone resorption and implant loosening. The use of β-type titanium with nontoxic alloying elements, such as niobium, as a novel candidate of implant material for replacing failed hard tissues has shown great potential. This review describes a titanium implant application alloyed with niobium and the mechanical properties and bioactivity of various titanium alloys sintered at different temperatures.

Effect of the Si Additions on the Mechanical Behaviour and High-Temperature Performance of Hydrogen Sintered 434L Stainless Steels

2009 ◽  
Vol 289-292 ◽  
pp. 195-202
Author(s):  
Asuncion Bautista ◽  
Francisco Velasco ◽  
A. González-Centeno
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Stainless Steels ◽  
Comparison Standard ◽  
Lower Mass ◽  
Vacuum Sintering ◽  
Sintering Atmosphere ◽  
Temperature Performance ◽  
Hardness Tests ◽  
Different Temperatures

Non-commercial, 434L ferritic stainless steel powders prealloyed with 2% of Si were uniaxially compacted at 700 MPa and sintered in 100% H2 atmosphere for 30 min at three different temperatures (1225, 1250 and 1275 °C). For comparison, standard, commercial 434L powders were sintered in the same conditions, and 434L+2%Si powders were also sintered in vacuum. The porosity and grain size of the 9 sintered stainless steels were measured by image analysis methods. Tensile strength and Vickers hardness tests show that the steels with 2% of Si exhibit higher mechanical properties. Oxidation tests were carried out in air at 800 and 900 °C. H2-sintered 434L steels prealloyed with Si exhibit higher weight gains per unit of apparent surface than 434L steels sintered in the same conditions, due to the higher porosity of the former. The sintering atmosphere affects the nature and morphology of the scales observed by XRD and SEM. Vacuum sintering of 434L+2%Si stainless steels promotes the formation of more protective scales and lower mass gains (for identical porosity volume) than H2 sintering.

Computer-Aided Optimized Design for Multi-Alloyed Steels Specifying Hardenability Requirements

2007 ◽  
Vol 353-358 ◽  
pp. 3112-3115
Author(s):  
Yue Peng Song ◽  
Xiao Zhang ◽  
Guo Quan Liu
Keyword(s):  
Computer Aided Design ◽  
Mathematic Model ◽  
Structural Steels ◽  
Design System ◽  
Optimized Design ◽  
Alloying Element ◽  
Computer Aided ◽  
Steel Grades ◽  
Improved Model ◽  
Aided Design

The Jominy end-quench curves of non-alloyed and alloyed steels can be predicted by nonlinear equation method. Without considering the interaction effects of alloying elements on the curves, however, the prediction for multi-alloyed steels may be different markedly from that experimentally determined. Hence, an improved mathematic model for predicting the Jominy end-quench curves of multi-alloyed steels was proposed by introducing a parameter named “alloying element interactions equivalent” to the nonlinear equations. With the improved model, the predicted Jominy curves agree very well with the experimental ones for more than 300 steel grades found in the literature. A computer-aided design system for hardenability of structural steels was then developed. The system not only can quantitatively evaluate the hardenability of structural steels, but also is very helpful to design steels and hardenability-aimed components. The optimal composition range of a new steel was so successfully designed as an example. Further research results show that the computer-aided design system so developed can also be used for monitoring of hardenability variation in steel industrial production.

The Formation of Multiphase Microstructures in Low-Alloy Steel

2010 ◽  
Vol 638-642 ◽  
pp. 3520-3530 ◽  
Author(s):  
Jilt Sietsma
Keyword(s):  
Mechanical Properties ◽  
Alloy Steel ◽  
Dual Phase ◽  
Low Alloy Steel ◽  
Microstructure Formation ◽  
Basic Principles ◽  
Dp Steel ◽  
Transformation Induced Plasticity ◽  
Steel Grades ◽  
Multiphase Steel

Although relatively simple in its chemical composition, low-alloy steel can form in a wide variety of microstructures, which directly implies that the (mechanical) properties of the material can vary strongly. Mankind has been using this to his advantage for ages, but the requirements for modern production and use of the material necessitate an ever better insight in the formation of these microstructures. Newly developed steel grades like DP-steel (Dual-Phase) or TRIP-steel (Transformation-Induced Plasticity) consist of several of the well-known phases ferrite, bainite, martensite, austenite, which need to be carefully balanced in their amount, composition and morphology to attain the desired material properties. An overview is given of the basic principles of microstructure formation in low-alloy steel, and the implications for several types of multiphase steel microstructures, in relation to the mechanical properties, are discussed.

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