Steel aluminum-killed

Aluminum iodide pentadecahydrate, 2 386 Aluminum-iron alloys, 2 308-309 Aluminum-iron-silicon alloys, 2 316-317 a-Aluminum-iron-silicon alloys, 2 317 intermetallic phases, 2 316t P-Aluminum-iron-silicon alloys, 2 317 intermetallic phases, 2 316t Aluminum-killed steel, continuous-cast,... 

Continuous carbon dioxide foaming, 24 21 Continuous-cast aluminum-killed steel, 23 270... 

Figure 5. Elongated manganese sulfide inclusion in aluminum killed steel after hot...

Figure 18 A relationship between the value and grain size of steel. The normal range of conventional rimmed and killed steels is shown. In addition to chemical composition, the value is determined by the coil processing. Two titanium-treated aluminum-killed steels are also shown. To produce an interstitial-free steel with a high r , value, the amount t)f titanium present must exceed six times the amount of carbon plus nitrogen. (From Ref.

Boron Small amounts increase hardenability, used only in aluminum-killed steels... 

Doloma Tundish Nozzle. When aluminum killed steels are cast, the upper tundish nozzle is prone to clogging. Alumina inclusions in the molten steel deposit on the nozzle bore and restrict steel flow from the tundish. At this point the nozzle can be physically reamed open with a rod however, this practice has an adverse effect on the steel quality, so generally the tundish is replaced by a new one. 

Argon purging of the upper tundish nozzle is common when aluminum killed steels are cast. This practice is effective in reducing the rate of alumina buildup on the nozzle bore, but it does not prevent it. Clogging of the upper nozzle limits tundish life in some steel plants. 

Doloma-based refractories have been applied to the continuous caster to prevent alumina clogging when casting aluminum killed steel grades. Tundish nozzles based on doloma have been used at BOF shops that cast a variety of aluminum killed steel grades. It was found that the sulfur content of the steel was critical with maintaining the clogging resistance of the doloma nozzles. 

Low-carbon plate and sheet are made in three qualities fully killed with silicon and aluminum, semikiUed (or balanced), and rimmed steel. Fully killed steels are used for pressure vessels. Most general-purpose structural mild steels are semikiUed steels. Rimming steels have minimum amounts of deoxidation and are used mainly as thin sheet for consumer applications. 

Above 75Q°F (400° C), use silicon-killed (not aluminum-killed) carbon steel. Above 85QflF (4S0BC), use lCr-%Mo or lWCr-%Mo,... 

As a grain-refining addition, niobium has a number of advantages. Unlike aluminum, it does not seriously affect the high-temperature yield stress or creep strength. Also, whereas aluminum-treated steel is necessarily fully killed, niobium may be added to semikilled steel. The latter is particularly advantageous in Britain, where industry is geared to the production and use of semikilled carbon steel. 

It is made from fine-grain, fuUy aluminum-killed (0.02% minimum residual), basic-oxygen steel containing 0.08 to 0.15% carbon, 0.27 to 0.63% manganese, 0.05% max. sulfur, and 0.035% maximum phosphorus. In the usual normalized condition, it has a minimum tensile strength of 40,000 psi, a minimum yield strength of 30,000 psi, and a minimum elongation of 40% in 2 inches. 

Aluminum (Al). Along with nitrogen, aluminum promotes the formation of a refined grain structure. Most importantly, aluminum is added as a deoxidizer to produced killed steel. 

The steel should be aluminum killed to secure a fine-grain material, but it is not certain that a small grain size per se is preferable to a large grain size. 

In the 1990s, trials of doloma-based refractories in the continuous casting of steel were started. It was felt that the high lime content (57%) of the doloma refractory would make it very effective in the prevention of alumina buildup during the continuous casting of aluminum killed carbon and stainless steels. Doloma graphite SENs and ceramic bonded doloma tundish nozzles have both been developed. 

Doloma Graphite SENs. Doloma graphite (DG) pouring shrouds were developed in order to reduce and/or eliminate the tendency for alumina deposition in the SEN or SES. The DG tubes have been used primarily for casting stainless steels prone to alumina clogging and aluminum killed carbon steels that are also prone to this problem. Alumina graphite (AG) are typically used in these applications however, alumina deposition is usually the limiting factor for their performance. Properties for several DG materials are shown as compared to a typical AG material in Table 9. 

The new continuous casting processes, in contrast to ingot cast products, provide tin mill products which are exceptionally clean and formable. The deoxidizing processes required for continuous casting involve either aluminum or silicon killing, which adds aluminum or silicon to the steel. Experience with type D steels indicates that the added aluminum will not cause a corrosion problem. Laubscher and Weyandt (18) have shown that the silicon found in silicon killed, continuous cast, heavily coated ETP will not adversely affect the corrosion performance of plain cans packed with mildly acid food products in which tin usually protects steel. The data on enameled cans is not definitive. Additional published data are required to determine whether or not silicon actually reduces the performance of enameled cans made from enameled, heavily coated, silicon killed, continuous cast ETP. 

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