scholarly journals Decarburization of ferrochrome and high alloy steels with optimized gas and slag phases towards improved Cr retention

2013 ◽  
Vol 49 (2) ◽  
pp. 175-181 ◽  
Author(s):  
H. Wang ◽  
M.M. Nzotta ◽  
L. Teng ◽  
S. Seetharaman
Keyword(s):  
Mass Transfer ◽  
Induction Furnace ◽  
Refining Process ◽  
Endothermic Reaction ◽  
High Carbon ◽  
High Alloy ◽  
High Alloy Steel ◽  
Carbon Ferrochrome ◽  
Alloy Steels ◽  
Gas Molecules

Chromium is a high value metal and the retention of the same during the refining of high carbon ferrochrome as well as high alloy steel has significant economic and environmental impacts. The loss of chromium during the decarburization is generally minimized using argon-oxygen mixtures thereby reducing the oxygen partial pressure (PO2) of the oxidant gas. In the current study, experiments were carried out in an induction furnace and CO2 was introduced with the view to partly reduce PO2 and partly as an oxidizer. During these experiments, the decarburization of molten Cr-alloy was conducted using pure O2, pure CO2 or O2+CO2 mixtures. The results demonstrated that the Cr loss can be minimized under CO2 introduction. The kinetic analysis showed that the mass transfer is effective due to the production of 2CO gas molecules from one CO2 molecule during the reaction which will improve the stirring of the bath. Besides, CO2 reacts with carbon in melt is an endothermic reaction, introduction of CO2 could be a cooler during the refining process, hence the temperature could be controlled by controlling the diluting gas amount, in this case, the over heat of bath refractory could be prevented and the lifetime of refractory could be extended.

scholarly journals Tool surface with a supporting plateau of hard particles for deep drawing of high alloy steel

2018 ◽  
Vol 190 ◽  
pp. 14006 ◽  
Author(s):  
Hannes Freiße ◽  
Thomas Seefeld
Keyword(s):  
Sheet Metal Forming ◽  
Deep Drawing ◽  
Metal Forming ◽  
Adhesive Wear ◽  
High Alloy ◽  
High Alloy Steel ◽  
Hard Particles ◽  
Aluminium Bronze ◽  
Tool Surface ◽  
Alloy Steels

Sheet metal forming normally requires the application of lubricants to protect the tool and the sheet against wear. The parts must be cleaned to remove the lubricants before joining and coating. This process step wastes energy and water resources. In the case of non-lubricated sheet metal forming, cleaning processes would not be necessary anymore and the process chain could be optimized regarding ecological and economical aspects. However, forming without lubrication leads to an intensive contact between the tool and the sheet. Thus, higher wear occurs and process reliability cannot be ensured for industrial mass production. High alloy steels are applied for mass-market products e.g. for appliances. Because of the higher strength, strain hardening and galling effects the austenitic steels are comparatively difficult to form. For dry metal forming of high alloy steels new tool concept must be developed to withstand the higher loads. In this work, a laser generated tool surface with a supporting plateau of hard particles (metal matrix composite (MMC-surface)) is presented. Spherical fused tungsten carbides were injected into the surface by laser melt injection. The metallic matrix of the composite was rejected by applying laser ablation. In consequence, the hard particles stood out of the matrix and were in direct contact with the sheet material. The surface of hard particles had a high hardness about 3000 HV and less metallic character. Cold working steel and aluminium bronze were tested as reference tool materials. Dry and lubricated forming experiments were carried out by strip drawing with bending and deep drawing of cups. Dry deep drawing of cups was not possible by using cold work tool steel. This can be traced back to the occurrence of wrinkles and cup base fracture at the same time. Applying aluminium bronze as tool material for dry metal forming resulted in high adhesive wear. Within this work the feasibility of dry metal forming of high alloy steel could be demonstrated by applying the MMC-surface whereby adhesive wear could be reduced.

scholarly journals Дослідження нагріву високолегованих сталей у нагрівальному колодязі з опаленням з центру поду

2018 ◽  
pp. 81-85
Author(s):  
O.I. Cheprasov ◽  
Yu. M. Kayukov ◽  
I.A. Nazarenko
Keyword(s):  
Initial Temperature ◽  
Temperature Drop ◽  
Exposure Period ◽  
Final Temperature ◽  
High Alloy ◽  
High Alloy Steel ◽  
Temperature State ◽  
Alloy Steels ◽  
Steel Grades ◽  
Steel Ingots

Purpose. Taking into account the steel grade, the mass of the set and the initial temperature state of the metal, it is necessary to estimate the final temperature drop in the steel ingots, which are heated in a recuperative heating well with heating from the hearth. Metodology. The study was performed in the process of heating high-alloy steels in a recuperative heating well by measuring the temperature in an experimental ingot. Findings. The results of thermometry of an experienced ingot with its nod as part of the high-alloy steel set are presented. The final temperature drop in the ingot and the nature of its change in the process of holding the metal have been established. Originality. It was established that the final temperature drop in the experimental ingot is determined by the unevenness of the temperature field of the heating well and is (80 ... 120) ° C. Practical value. Using research results allows us to develop heating modes for stainless steel grades with a shorter (10 ... 20)% exposure period.

Equilibrium concentration of carbon in high-carbon high-alloy steel during carbon partitioning process

2016 ◽  
Vol 33 (3) ◽  
pp. 363-369
Author(s):  
L. N. Zhou ◽  
G. Z. Tang ◽  
X. X. Ma ◽  
L. Q. Wang ◽  
T. B. Wu ◽  
...  
Keyword(s):  
Alloy Steel ◽  
Equilibrium Concentration ◽  
Carbon Partitioning ◽  
High Carbon ◽  
High Alloy ◽  
High Alloy Steel

Kinetics Analysis on Process of Direct Smelting and Alloying between High-Carbon Ferrochrome and Molybdenum Oxide

2015 ◽  
Vol 1095 ◽  
pp. 766-769
Author(s):  
Hong Ming Wang ◽  
Yang Li ◽  
Xiao Jian Fan ◽  
Gui Rong Li
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Contact Area ◽  
Reduction Rate ◽  
Phase Contact ◽  
High Carbon ◽  
Dissolved Carbon ◽  
Carbon Ferrochrome ◽  
Direct Smelting ◽  
Co Gas

Based on the direct reduction alloying theory, the kinetics investigations on process of direct smelting and alloying between high-carbon ferrochrome and molybdenum were conducted. The results indicate that at the high temperature MoO3(g) can easily reduced by carbon dissolved in iron liquid. Reducing the volatilization loss of MoO3is the most effective measure to increase the Mo yield. With regard to the reaction between CaMoO4(l) and dissolved carbon at steelmaking temperature, the increases of mass transfer coefficient of CaMoO4in slag and phase contact area between metal and slag make for increasing the reduction rate. CO gas generated from extra carbon acting as reducing agent can provide favorable kinetics conditions for reduction reaction. The reaction between Cr7C3(l) and MoO3(l) in liquid steel is similar to the reaction between CaMoO4(l) and dissolved carbon. The incensement of mass transfer coefficient of MoO3(l) in slag can improve the reduction rate effectively. The CO gas generated from reaction can stir molten bath promote foam slag formation, so as to increase the phase contact area, which provides favorable kinetics condition.

scholarly journals Development of Universal Mould Geometry for the Teeming of Cylindrical Iron-Base Alloy Ingots

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 471
Author(s):  
Josef Odehnal ◽  
Pavel Ludvík ◽  
Tomáš Studecký ◽  
Pavel Michálek
Keyword(s):  
Alloy Steel ◽  
Base Alloy ◽  
Cast Steel ◽  
Solidification Process ◽  
High Alloy ◽  
High Alloy Steel ◽  
Iron Base Alloy ◽  
Steel Grades ◽  
Borated Stainless Steel ◽  
Filling And Solidification

The presented work is aimed at developing a mould geometry suitable for casting both low- and high-alloy steel grades into 500 kg experimental ingots. The high Height-to-Diameter (H/D)-ratio mould currently used in COMTES FHT Inc. served as a reference and for finite element method simulations (FEM) of the filling and solidification process. The optimized mould geometry, balancing the porosity and segregations, was determined using MAGMA software. Four different steel grades were defined for the simulation. Case studies were carried out for 34CrNiMo6 (W.Nr. 1.6582), DHQ8, CB2 and borated stainless steel grades ranging from low-alloy steel to high-alloy steel. Extended user-defined criteria and verified boundary conditions were used to predict the formation of A-segregations in cast steel. Both primary (PDAS) and secondary (SDAS) arm spacings were modelled as well. The optimized mould shape and the casting assembly were designed based on the simulation results.

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