Technical terms for steel properties

Aging – Changes in the physical and mechanical properties of low-carbon steel after a period of storage. Increased temperature accelerates the aging process.

Annealing – A processing technique involving high-temperature heating and cooling of a cold-rolled sheet to reduce its hardness, making it softer or easier to form.

Sickle Bending – The deviation of one edge of a strip from a straight line; measured by taking the concave surface of the straight edge.

Carbon Steel – Primarily refers to steel whose mechanical properties depend on its carbon content and generally do not contain large amounts of alloying elements; sometimes also called plain carbon steel or carbon steel.

Chemical Treatment – A processing technique involving coating the surface of plated products with waterproof and corrosion-resistant chemicals such as chromates or phosphates.

Tensile Strain Marks – Surface defects such as a series of parallel lines at a 45° angle to the rolling direction, irregular folds, or orange peel patterns, appearing on the sheet after stamping. These defects typically extend across the entire width of the steel sheet or strip. They are caused by the aging of the steel.

Cold-rolled products - Flat rolled products rolled at room temperature to achieve the required final thickness and dimensional requirements.

Commercial grade steel (CS) - This quality of sheet metal can be easily bent or lightly formed. At room temperature, it can be bent and conform to itself in any direction.

Continuous casting - The process of continuously drawing and solidifying a continuous cast billet from the bottom of a crystallizer.

Corrosion - The gradual chemical or electrochemical corrosion of metals under the influence of moisture or other media in the atmosphere.

Critical surfaces - Surfaces intended for exposure or painting; surface defects that would affect the coating should be avoided.

Coverage - The profile of a steel sheet whose thickness gradually increases from the edge to the center.

Sheared edge - The edge shape formed after shearing the edge of the strip to obtain the user-specified width.

Sheared length - Specified equal or unequal lengths.

Deep drawing - A processing technique that uses a die on a punch press to shape a metal billet into a cup-like shape.

Stamping – A machining process that forces the plastic flow of metal into a concave shape using a die to form a part.

Stamping Steel (DS) – This quality grade of steel offers higher ductility and property uniformity compared to commercial steel.

Deep Drawing Steel (DDS) – Deep drawing steel is used when the ductility of stamping steel cannot meet the stringent requirements of manufacturing parts, or when the steel sheet must not exhibit aging. Its properties are achieved through special smelting and manufacturing processes.

Bake Hardening Steel – This steel possesses both strength and high formability. The strength of the final part is achieved through work hardening during processing and aging during the baking process.

Ultra-Deep Drawing Steel – This steel offers excellent formability and superior property uniformity. It is a gapless steel with very low carbon content and added alloying stabilizing elements. It is a steel that does not undergo aging.

DS Type B Steel – Used for products with more stringent stamping and forming requirements.

Ductility – The allowable deformation capacity before fracture. For flat rolled products, ductility is typically measured by hardness or mechanical properties in tensile tests.

Elongation after fracture – The percentage of elongation at break of a specified length before fracture in a tensile test.

Straightness – A measure of how well a steel sheet conforms to a horizontal plane. It is usually measured by the flatness index, which refers to the maximum deviation of the steel sheet surface from the horizontal plane. Straightness can also be expressed in steepness or units (I).

Hardness – The ability of a metal surface to resist indentation.

High-strength low-alloy steel (HSLA) – A specific class of steels that achieves the desired strength level by adding small amounts of alloying elements. The most common alloying elements are niobium, vanadium, and titanium.

Hot-rolled sheet – A steel sheet rolled at high temperatures on hot rolling mills to its final thickness.

Hot-rolled pickled product – A hot-rolled product that has undergone pickling, oiling, leveling, and trimming to meet specified dimensions and tolerances.

Inclusions – Foreign substances (such as oxides, sulfides, or silicates) present in the steel after casting. Inclusion Shape Control – Using rare earth metals or calcium alloys to control the morphology of inclusions, providing improved mechanical properties for specific applications.

Killed Steel – Deoxidized steel with silicon or aluminum before solidification, minimizing the oxygen content in the molten steel. Compared to other types of steel, killed steel has more uniform properties and chemical composition.

Straightening – Straightening rolled sheets by reducing or eliminating deformation.

Mechanical Properties – The elastic and inelastic properties exhibited by a material when subjected to external forces, indicating its suitability for mechanical applications.

Oil Coating – Oiling after pickling or leveling rolling reduces scuffing between coils, improves lubrication, and provides a degree of rust prevention, aiding customers in processing their products.

Oiled Sheet – Sheet metal products with oiled surfaces after final processing. The purpose of oiling is usually to prevent rust during transportation and storage. These oils are called rust-preventive oils. Oiling can also aid in subsequent processing, but this is usually not the primary purpose. Oils used to improve formability are often called "pre-lubricants."

Pickling – Removing oxides from metal surfaces through a chemical reaction.

Pre-lubricant – An oily coating applied to steel sheets to improve formability (deep drawing). This type of lubricant is used when the user wishes to avoid applying forming lubricants to their workpiece.

Quality – A term used to describe the perfection of a steel sheet. It usually refers to the surface quality of the steel sheet, such as the absence of scratches and cracks. Quality can also refer to other characteristics, such as the absence of internal defects and the precision of dimensional control.

Roll forming – A processing technology in which metal sheets are continuously deformed in a single pass through a series of continuous rollers to obtain a predetermined shape.

Slitting – A processing technology that cuts a steel sheet into two or more sections in the width direction.

Swivel – Generally refers to the appearance of the grains formed after hot-dip galvanized sheets are drawn from the zinc pot and the zinc layer cools and solidifies. The size, brightness, and surface morphology of the swivel depend on a number of factors, but are mainly related to the zinc layer composition and cooling method.

Structural steel: refers to steel that meets specific strength and formability grades. Formability is expressed as elongation after the tensile test is interrupted. Structural steel is generally used for load-bearing applications, where strength is an important design criterion.

T-bend: A mechanical operation that allows a sheet metal sample to be bent to fit itself with an inner bending radius determined based on the sheet thickness. For example, 2T indicates that the bending radius is equal to twice the thickness of the tested steel sheet.

Tensive straightening: A process of stretching a steel coil through a tensile straightening device to exceed the product's yield point, causing permanent deformation. Tensile straightening achieves good straightness.

Leveling rolling: A process of slightly thinning and cold-pressing a steel sheet. Leveling aims to improve straightness, eliminate discontinuous plastic deformation, and obtain a uniform surface.

Tensive strength: The maximum stress a material can withstand in a tensile test. It is the ratio of the maximum load to the original cross-sectional area.

Tolerance: A term for the allowable deviation of a dimension. For example, sheet metal thickness, width, straightness, and camber have tolerances.

Yield point – The load or stress value at which steel continues to deform even without further increase in applied load is called the yield point. Yield point is one of the characteristics of low-carbon steel after annealing.

Yield strength – The stress corresponding to a specified value when the material deviates from the linear segment of the load-elongation curve. In tensile tests, the yield strength of a material is usually defined as the load corresponding to a 0.2% strain deviation from the linear segment of the curve.