Uddeholm Tooling Research Articles

The CO2 -binding by Ca-Mg-silicates in direct aqueous carbonation of oil shale ash and steel slag

Abstract This study was focused on carbonation of waste materials having low water-solubility in which Ca and Mg are generally bound as silicates. Here, pulverized firing oil shale ash (PFA from Narva Power Plants, Estonia), electric arc furnace slag (EAFS, types 1 and 2 from Uddeholm Tooling, Sweden) and ladle slag (LS from Uddeholm Tooling, Sweden) were studied as sorbents for binding CO 2 from flue gases in direct aqueous mineral carbonation process. The experiments were carried out at room temperature and atmospheric pressure. Results showed that Ca-Mg-silicate phases bound up to 9 g of CO 2 per 100 g of initial ash, which formed 30% of the total CO 2 bound in direct aqueous carbonation of PFA. The CO 2 uptakes for steel slags (EAFS1, EAFS2 and LS) were 8.7 g CO 2 /100 g EAFS1, 1.9 g CO 2 /100 gEAFS2 and 4.6 g/100 g LS. Quantitative XRD analysis indicated that Ca 2 SiO 4 and Ca 3 Mg(SiO 4 ) 2 were the main CO 2 binding low solubility components of oil shale ash as well as steel slags. The main carbonation product was calcite (CaCO 3 ), indicating that Mg-compounds were not reactive towards CO 2 at these mild conditions. Based on multifaceted studies on carbonation of oil shale ash, a new method for eliminating CO 2 from flue gases by Ca-containing waste material was proposed. The process includes contacting the aqueous suspensions of Ca-containing waste material with CO 2 containing flue gas in two steps: in the first step the suspension is bubbled with flue gas keeping the pH levels in the range of 10–12 and in the second step keeping the pH levels in the range of 7–8. The water-soluble components such as free lime are carbonated in the first step and the components of low solubility, in which Ca is generally contained in the form of silicates, are carbonated in the second step.

Retention, Recovery and Recycling of Metal Values from High Alloyed Steel Slags

Retention, Recovery and Recycling of Metal Values from High Alloyed Steel SlagsThe work was carried out in four parallel directions. The thermodynamic activities of oxides of Cr in steel slags were determined by slag-gas equilibration technique. The ratio of Cr2+/Cr3+in CaO-MgO(-FeO)-AlO3-SiO2-CrO×system slags was measured by X-ray absorption near edge spectra (XANES). High-temperature mass spectrometry method was also used to obtain the distribution of chromium oxides. A mathematical correlation was established for estimating the ratio of Cr2+/Cr3+as a function of temperature, partial pressure of oxygen and slag basicity. Laboratory investigations of the decarburization of high alloy steels under controlled oxygen potentials have been carried out to retain Cr in the steel phase. A mathematical model has been developed for the decarburization process with controlled oxygen partial pressure. Experimental and theoretical investigations have been carried out in optimizing the Mo-additions to steel in the EAF practice in Uddeholm Tooling AB. Substantial saving of Mo as well as less emissions of Mo-bearing dust are indicated in the study. A salt extraction process was developed to extract the metal values from steel slags. Successful extractions, followed by electrolysis indicate that this could be a viable route towards recovery of metals from metallurgical slags.

Inclusions Generated during Ingot Casting of Tool Steel

AbstractAn industrial trial study was carried out at Uddeholm Tooling AB, Sweden, to investigate the mechanisms of the formation of inclusions, especially macro inclusions during ingot casting. Strong evidence of reoxidation was observed. Two types of inclusions generated during casting were detected in the ingot. Inclusions of Type C1 originated from mould powder with reoxidation product Al2O3 as a part of it. Inclusions of this type were usually small. The number of Type C1 inclusions increased from the centre of the ingot toward the side wall of the mould. Type C2 inclusions were macro size. They could be the results of reoxidation and erosion of runner.

The Effect of Ladle Treatment on Inclusion Composition in Tool Steel Production

An in‐depth SEM‐investigation of the inclusion composition change in the ladle refining process during tool steel production was done. Plant trials were carried out at Uddeholm Tooling AB in Hagfors, Sweden. A series of samples was taken during ladle refining, from deslagging through vacuum treatment. The goal was evaluating the effects of the top slag and other process parameters on the inclusion composition during ladle refining. The main conclusion was that normal variations in the process have a large influence on inclusion composition. Furthermore, it was concluded that the MgO content in the top slag had a large influence on the inclusion composition throughout the whole ladle refining process. Also, the SiO2 content in the ladle slag originating from the EAF‐slag, had a noticeable effect on the inclusions. The inclusions belonging to the system Al2O3‐CaO‐MgO‐SiO2 showed a continuous composition change throughout the ladle refining process, from high Al2O3, via MgO‐spinel to finally complex types rich in CaO and Al2O3.

MATERIAL RESPONSE OF RAMAX-2 DURING HIGH-SPEED MACHINING USING QUICK-STOP DEVICE

Ramax-2 is chromium-alloyed stainless holder steel. It is manufactured by Uddeholm Tooling AB (Hagfors, Sweden) and supplied in prehardened and tempered condition. It is used for plastic and rubber molds and for dies for plastic extrusion. It has excellent machinability and corrosion resistance and has uniform hardness comparable with AISI 420F. It was machined by turning process and the formation of shear bands and their width was observed in the chips collected at cutting speeds from 50 to 250 m/min. The chemical composition of the workpiece material is given in Table 1. The mechanical and physical properties are given in Table 2. The samples were taken from a round bar of 28 mm diameter. The purpose of this research was to experimentally measure the response of Ramax-2 at cutting speeds ranging from 50 to 250 m/min, the upper limit being in the domain of high-speed machining. Shear band formation at various strain rates will be measured, and consequently, the strain rates generated in high-speed machining of Ramax-2 will be calculated.

A new approach for the study of slag–metal interface in steelmaking

The main focus of the present work was to develop a sampler to obtain the physical description of the slag–metal interface in the presence of bulk flow. Industrial trial experiments were carried out in the ladles at Uddeholm Tooling, Hagfors, Sweden using the designed sampler. Samples of the slag–metal interface were successfully taken in both gas stirring and induction stirring modes. The similarities of the appearance as well as the micrographs of the samples suggested that the slag–metal interfaces in the two stirring modes were very similar except in the open eye area. In the case of both stirring modes, metal droplets were found in the slag bulk. On the other hand, no appreciable amount of slag was detected in the metal bulk. Further systematic investigation using a large number of samples is required to obtain a quantitative description of the interface.

An Experimental Study of Number Concentration Gradients of Inclusions during Deoxidation using Inductive and Gas Stirring

Concentration gradients of inclusions during inductive and gas stirring of AISI H13 tool steel in a ladle have been studied using a unique experimental technique at Uddeholm Tooling AB in Sweden. ...

Impact of slag–refractory lining reactions on the formation of inclusions in steel

The present study was carried out to investigate the impact of slag– refractory lining reactions on the formation of inclusions during ladle treatment of steel. The experiments were conducted on an industrial scale in the ladle at Uddeholm Tooling AB in Hagfors, Sweden. The inclusion chemistry and population during ladle treatment were studied along with the composition of the ladle glaze, taken from the ladle lining. The inclusions in the steel were classified into four groups according to the Swedish standard SS 111116. SEM/EDS analyses were carried out to identify the phases present in both the inclusions and the ladle glaze. The number of inclusions in the steel before deoxidation was found to increase with the ladle age, i.e. the number of times the ladle had been in use. A similar increase was also found after vacuum degassing and before casting. A great portion of inclusions before casting was found to be supplied by ladle glaze. This observation was further confirmed and explained by thermodynamic analysis. The present results show that ladle glaze is a major source of inclusions in the ladle at Uddeholm Tooling.

Non‐metallic inclusions in the ingot and final products of a medium‐carbon tool steel

The present work was carried out at Uddeholm Tooling AB, Sweden to study the inclusion characteristics in the ingot and the final product of a ‘medium‐carbon’ tool steel. Steel samples were taken during the mould filling, after casting and from the final product. The inclusion populations in the steel samples were examined under a light optical microscope. The chemical compositions of the inclusions were analysed using a scanning electron microscope attached with EDX. The steel samples taken during the mould filling were found to contain alumina‐based inclusions, originated from the erosion of the closing gates, the inner nozzle and the outer nozzle. The analyses of the steel samples from the solidified ingot revealed a non‐uniform distribution of inclusions. The inclusion population was found to be highest in the centre part of the ingot and lowest between the central line and the mould wall. The steel samples from the bars of the final products were taken at an identical position in each case, corresponding to the central part of the ingot. The inclusion populations were found to be somewhat higher in the final product in comparison with the populations before casting. The inclusion populations in the final products were also found to increase with the ladle age.

Ladle glaze: major source of oxide inclusions during ladle treatment of steel

Samples of ladle lining covered by glaze were taken from industrial ladles of different ages at Uddeholm Tooling AB, Hagfors, Sweden. It was found in the samples taken at and below the slag line that a slag infiltrated layer was covered by an outer layer containing many MgO 'islands' of various sizes. The microstructure of the infiltrating slag was the same as the matrix of the outer layer. The slag was found to decompose into the compound 3CaO.Al2O3 and a liquid phase during the cooling process. The former phase along with tiny MgO particles from the ladle glaze was found to be one of the major sources of inclusions during the degassing and flotation periods of ladle treatment. Thermodynamic analysis indicated that the reaction between the ladle glaze and the slag from the electric arc furnace resulted in the formation of MgO–Al2O3 spinel and an oxide solution, which were also the main inclusions found at the initial stages of ladle treatment. Evidence of this reaction was found in the lining samples taken above the slag line.

Effect of ladle age on formation of non-metallic inclusions in ladle treatment

An experimental study was carried out at Uddeholm Tooling, Hagfors, Sweden to examine the impact of ladle glaze on the formation of non-metallic inclusions during the ladle treatment process. Steel samples were taken at various stages of the process and from ladles of different ages. Inclusion numbers were counted under an optical microscope. It was found that the total number of inclusions increased with the ladle age before deoxidation and at the end of the ladle treatment. The increase was substantial after the ladle had been used more than 18 times. Inclusions having the smallest sizes were found to make a large contribution to this increase. This observation was further confirmed by the difference between total oxygen content and dissolved oxygen content in the steel samples, which also showed an increase with ladle age. Analysis by SEM–EDX revealed two types of inclusions before casting, namely, inclusions consisting only of an oxide solution having a composition very close to 3CaO. Al2O3, and inclusions consisting of the same oxide solution as well as MgO phase. This finding was in accordance with the reported result that both 3CaO. Al2O3 and MgO were present in the slag infiltrated layer of the ladle glaze. It was concluded that ladle glaze is the foremost source of non-metallic inclusions in tool steel during ladle treatment.

Studies on dust recycling in the electric arc furnace at Uddeholm Tooling AB

The electric arc furnace (EAF) generates dust containing about 21% Zn during primary steelmaking at Uddeholm Tooling AB. Research work on upgrading of the dust has been carried out jointly by Uddeholm Tooling AB and MiMeR, Minerals and Metals Recycling Research Centre, at Luleå University of Technology. The work included laboratory studies and plant trials. The laboratory studies, with 6 dust smelting tests at temperatures around 1650°C, demonstrated that the smelting had no negative effects on qualities of the steel and slag. It was also shown that both carbon and silicon could be used to reduce the oxides in the dust, leading to high metal recoveries. Based on the study results, plant trials were performed at Uddeholm Tooling AB. The trials consisted of 100 EAF heats, recycling dust at a rate of 925 kg/heat. No negative impact has been found on the furnace products and production. The Zn content of the obtained dust increased by 11% and the weight of the generated dust decreased by 42%. The material costs for the dust recycling during the trials were rather low, $0.4 (4–5 SEK)/tonne steel. Some of the test results are interpreted by virtue of mass and energy balances of the dust smelting calculated using the computer software “Chemsage.” By utilizing results from the tests and calculations, the energy consumption for dust smelting was estimated.

Determination of macroinclusions during clean steel production

There are very few macroinclusions in clean steel, but the few that exist are very harmful for material properties of the final steel product. To date, very little information on large, so called macroinclusions in clean steel production has been presented. Therefore, the present study has focused on providing information on these inclusions during different stages of the steelmaking process, based on plant trials carried out at Uddeholm Tooling, Hagfors, Sweden. Macroinclusion size distributions have been determined using optical microscopy and classified according to a modified version of the Swedish standard SS 111116, as well as using immersed ultrasonic scanning. For the sake of completeness, the size distribution of microinclusions has also been determined using optical microscopy. Inclusion compositions were determined using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). Two types of liquid steel sampler were used in the investigation: a rapid solidifying (RS) sampler and the LSHR (liquid sampling hot rolling) sampler, suitable for immersed ultrasonic scanning. The results are critically discussed with respect to process conditions, such as alloy additions that took place during the plant trials.

Study of the deoxidation of steel with aluminum wire injection in a gas-stirred ladle

In the present work, the deoxidation of liquid steel with aluminum wire injection in a gas-stirred ladle was studied by mathematical modeling using a computational fluid dynamics (CFD) approach. This was complemented by an industrial trial study conducted at Uddeholm Tooling AB (Hagfors, Sweden). The results of the industrial trials were found to be in accordance with the results of the model calculation. In order to study the aspect of nucleation of alumina, emphasis was given to the initial period of deoxidation, when aluminum wire was injected into the bath. The concentration distributions of aluminum and oxygen were calculated both by considering and not considering the chemical reaction. Both calculations revealed that the driving force for the nucleation fo Al2O3 was very high in the region near the upper surface of the bath and close to the wire injection. The estimated nucleation rate in the vicinity of the aluminum wire injection point was much higher than the recommended value for spontaneously homogeneous nucleation, 103 nuclei/(cm3/s). The results of the model calculation also showed that the alumina nuclei generated at the vicinity of the wire injection point are transported to other regions by the flow.

RAMAX S

Abstract Uddeholm Ramax S is a 17-chromium alloyed-stainless holder steel that is supplied in the hardened and tempered condition. The alloy has both excellent corrosion resistance and machinability. Applications include corrosive plastic molds. 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 heat treating, machining, and joining. Filing Code: SS-778. Producer or source: Uddeholm Tooling Svenska AB. See also Alloy Digest SS-499, December 1988.

CORRAX

Abstract CORRAX is a precipitation-hardening (PH) stainless mold steel that may be used for many demanding applications. Its superior resistance to corrosion, combined with a hardness of up to 50 HRC, makes it well suited for molds making medical parts, all molds running in a clean-room environment, parts made of corrosive plastics (such as polyvinyl chloride, PVC), and molds for parts made of rubber. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating, machining, joining, and surface treatment. Filing Code: SS-774. Producer or source: Uddeholm Tooling Svenska AB.

OPTIMAX

Abstract Mold steels need to meet high demands, especially for surface finish. OPTIMAX is a stainless mold steel designed to have good characteristics in polishability, corrosion resistance, wear resistance, machinability, and hardening. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating and surface treatment. Filing Code: SS-759. Producer or source: Uddeholm Tooling Svenska AB.

PM tool steels for cold work applications: O.Sandberg, L.Jönson. (Uddeholm Tooling AB, Hagfors, Sweden.)

PM tool steels for cold work applications: O.Sandberg, L.Jönson. (Uddeholm Tooling AB, Hagfors, Sweden.)

UDDEHOLM AISI D2

Abstract Uddeholm AISI D2 is a high-carbon, high-chromium, air-hardening tool and die steel capable of great hardness and high resistance to abrasive wear. It is nondeforming and is also somewhat corrosion resistant. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on heat treating, machining, and joining. Filing Code: TS-567. Producer or source: Uddeholm Tooling AB.

VANADIS 30

Abstract Vanadis 30 is cobalt alloyed high-performance, high-speed steel made by powder metallurgy. The cobalt addition of approximately 8.5% has a positive influence on the hot strength, hot hardness, temper resistance, and modulus of elasticity. Punches are a suitable application for this alloy. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on wear resistance as well as heat treating and surface treatment. Filing Code: TS-566. Producer or source: Uddeholm Tooling AB.