Steel Glossary-D
time2017/03/18
Deburring 3
The process used to smooth the sharp, jagged edges of a cut piece of steel.
Deep Drawing Applications 1
Parts/applications that require deep drawing in their fabrication. Examples are motor shells, fenders, quarter panels, and door panels.
Defined Benefit Retirement Plan
A type of pension plan whereby the employer promises to make pension payments to retired employees in specified amounts, regardless of the performance of the fund. Because the employees’ total years of service and their length of retirement are uncertain, the employer’s future liabilities must be estimated and can fluctuate over time.
Defined Contribution Retirement Plan
A pension plan in which the employer promises to make specified contributions to the pension fund, but the amount of pension benefits ultimately paid to retired employees depends on how well the pension fund’s assets are managed. There are no balance sheet items for Defined Contribution Plans because all liabilities are satisfied in full each year.
Descaling 1
The process of removing scale from the surface of steel. Scale forms most readily when the steel is hot by union oxygen with iron. Common methods are: (1) crack the scale by use of roughened rolls and remove by a forceful water spray, (2) throw salt or wet sand or wet burlap on the steel just previous to its passage through the rolls.
Desulfurization
What?
Operation that injects a chemical mixture into a ladle full of hot metal to remove sulfur prior to its charging into the Basic Oxygen Furnace.
Why?
Sulfur enters the steel from the coke in the blast furnace smelting operation, and there is little the steelmaker can do to reduce its presence. Because excess sulfur in the steel impedes its welding and forming characteristics, the mill must add this step to the steelmaking process.
Direct Reduced Iron (DRI)
What?
Processed iron ore that is iron-rich enough to be used as a scrap substitute in electric furnace steelmaking.
Why?
As minimills expand their product abilities to sheet steel, they require much higher grades of scrap to approach integrated mill quality. Enabling the minimills to use iron ore without the blast furnace, DRI can serve as a low residual raw material and alleviate the minimills’ dependence on cleaner, higher priced scrap.
How?
The impurities in the crushed iron ore are driven off through the use of massive amounts of natural gas. While the result is 97% pure iron (compared with blast furnace hot metal, which, because it is saturated with carbon, is only 93% iron), DRI is only economically feasible in regions where natural gas is attractively priced.
Drawn-Over-Mandrel
A procedure for producing specialty tubing using a drawbench to pull tubing through a die and over a mandrel, giving excellent control over the inside diameter and wall thickness. Advantages of this technique are its inside and outside surface quality and gauge tolerance. Major markets include automotive applications and hydraulic cylinders.
Drill Pipe
Pipe used in the drilling of an oil or gas well. Drill pipe is the conduit between the wellhead motor and the drill bit. Drilling mud is pumped down the center of the pipe during drilling, to lubricate the drill bit and transmit the drilled core to the surface. Because of the high stress, torque and temperature associated with well drilling, drill pipe is a seamless product.
Ductility
Ability of steel to undergo permanent changes in shape without fracture at room temperature.
Dumping
Dumping occurs when imported merchandise is sold in, or for export to the domestic market at less than the normal value of the merchandise — that is, at a price that is less than the price at which identical or similar merchandise is sold in the comparison market, the home market (the market of the exporting country), or third-country market (in this case, “market” is used as proxy for “home market” in cases where home market cannot be used). The normal value of the merchandise cannot be below the cost of production.
Dumping Margin
The amount by which the normal value exceeds the export price or constructed export price of the subject merchandise.
Duplex
A category of stainless steel with high amounts of chromium and moderate nickel content. The duplex class is so named because it is a mixture of austenitic (chromium-nickel stainless class) and ferritic (plain chromium stainless category) structures. This combination was originated to offer more strength than either of those stainless steels. Duplex stainless steels provide high resistance to stress corrosion cracking (formation of cracks caused by a combination of corrosion and stress) and are suitable for heat exchangers, desalination plants, and marine applications.