SAE steel grades

Steel grades are the different types of steels. Other designations are steel brand or quality; these names are but dated. The grades differ in their characteristics guaranteed by the manufacturer, which are achieved by varying the composition and thermal treatment.

The designation of steels in Europe is set in EN 10027-1 and 10027-2. In addition to the simple but abstract classification by number of each steel still gets a nickname, which mainly depends on its use determination. Furthermore, it is customary to classify steel on its chemical composition.

Material nicknames

Unalloyed steels

Mass steels / Steels for structural steel

In the structure of the steels according to EN 10025 Structural steels get the prefix symbol S for "structural steel". The following figure indicates the characteristic yield strength in N / mm ². Earlier structural steels were in Germany after the now withdrawn standard DIN 17100 refers to: St x with x = 1 /10 of the tensile strength in N / mm ² structural steels mechanical properties are therefore only with respect characterizes a steel with the same ( still prevalent in language use. ) designation may vary by manufacturer and batch partly have significantly different chemical compositions.

The first letter after the yield point provide information on the impact strength. The following letters indicate other mechanical properties or the intended use of the steel produced. Examples:

• K: cold formed
• A: annealed
• N: normalized
• V: quenched and tempered

Such as a steel is cast, can be characterized by the following identifiers:

• FU: effervescent shed (that is, with a lot of residual oxygen and pronounced segregation zones )
• FN: simply soothes shed (that is, with less residual oxygen)
• FF: double calms (or called fully killed ) shed (that is, virtually all of the oxygen slagged )

Calmed casting of steel means: In the conversion of pig iron to crude steel by the Linz- Donawitz process either silicon or aluminum is added ( in the simple reassurance ) or silicon and aluminum ( at twice the calming ) the liquid material. The effect of these elements that the existing oxygen in the melt is bound to these elements and slagged.

The term " sedation" is due to the fact that during cooling, the solubility of oxygen in the iron and therefore decreases the molten steel during the discharge oxygen " eliminated " and begins to bubble as boiling water. By adding one or both elements of this elimination process is more short term, but then stops suddenly when the oxygen is tied. Only killed steel is ever vergießfähig in the continuous casting process. In addition, the cast steel has calmed down because of its low or non-existent air pockets and the non-existent, pronounced segregation zone better mechanical properties and better weldability.

By October 2004, there was also a quality labeling, which would point to calming and heat treatment condition of the finished product, as they made ​​the manufacturer corresponding specifications:

• G1: If today as good as no longer produced, as in the continuous casting process a rimmed steel may no longer be shed. This would technically only in permanent mold casting possible, but not economically. There is under present circumstances no rational reason why a rimmed steel should be used because it always attracts quality defects in the form of air inclusions in steel by itself.
• G2: Rimming steel not permitted, not normalized steel
• G3: Fully killed steel normalized
• G4: The heat treatment condition of the product is left to the manufacturer. For example: normalized
• Quenched and tempered ( water, air or oil- tempered and a combination of these methods )

Non-alloy quality steels

Non-alloy quality steels are steels, such as exist for the generally established requirements for toughness, grain size and / or formability and which do not meet the definition of non-alloyed stainless steels. The carbon content is 0.2 to 0.65%

• Title: Cx with x = carbon content in percent by mass multiplied by 100
• Reduced content of phosphorus and sulfur compared to ordinary steels (less than 0.045 percent by mass)
• Usually provided no heat treatment
• Example: C60 is a quality steel with a carbon content of 0.60 mass percent.

Previously, the label has been written with spaces, according to the new standard eliminates the space between C and percentage.

Unalloyed steels

Have Unalloyed steels, particularly with regard to non-metallic inclusions, a higher degree of purity than quality steels. This stainless steels do not necessarily reflect the colloquial term of the stainless steel as stainless steel, but unalloyed steels are defined in EN 10020 as steel grades that correspond to one or more of the following requirements:

Name as that of unalloyed carbon steels, but with an attached letter E: cxe ( Cx carbon content in percent by mass multiplied by 100)

• Fixed minimum value of the impact energy (see resistance),
• Specified depth of hardening or surface hardness,
• Very low levels of non-metallic inclusions,
• Further reduced content of phosphorus and sulfur compared to carbon steels (< 0.025 %)
• Electrical conductivity over 9 S * m / mm ²
• Microalloyed steels with niobium, vanadium and / or titanium alloy below the respective limit
• Prestressed steels
• Nuclear reactor steels with limited levels of copper ( ≤ 0.1 %), cobalt ( ≤ 0.05 %) and vanadium ( ≤ 0.05%)

Example: C45E is a stainless steel with a carbon content of 0.45 mass percent. Previous designation according to DIN 17200 (withdrawn 1991): Ck 45

Microalloyed steels

Is referred to as a microalloyed steel, which is alloyed with 0.01 to 0.1 percent by mass of aluminum, niobium, vanadium and / or titanium, in order to achieve a high strength, for example through formation of carbides and nitrides, and grain refinement. Your nickname can be broken down as structural steels from the minimum yield strength:

Example of steel with the material number 1.0545:

• New designation according to EN 10113: sxn, example: S355N
• Old designation to DIN 17102: StU x with x = minimum yield stress in N / mm ², example: StU 355

The alloying elements partially dissolve when heated to forming temperature. They are targeted at cooling with carbon carbides and nitrides with nitrogen. These are finely dispersed in the ferrite and ferrite in the pearlite. The grain refinement caused thereby increases the strength without degrading the toughness.

Low-alloy steels

As low-alloy steels is known in which no alloy element exceeds an average content of 5 percent by mass.

Name:

• At the front, the carbon content in percent by weight times 100, followed by the chemical element symbols of the alloying elements in order of decreasing mass fractions, and end up in the same order, separated by hyphens, the mass fractions of the alloying elements listed above which were multiplied by the following factors in order to more integers to come: X 1000: B X 100: C, N, P, S, Ce × 10: Al, Cu, Mo, Ti, V, Be, Ta, Zr, Nb, Pb × 4: Cr, Co, Mn, Ni, Si, W

Mnemonics for factor 4 are: Cr, Co, Mn, Ni, Si, W "Chrome could not safely perceive " or "You Never Looks 4 White Crocodile "; factor of 10 for " AlCuMoTaTiV "

High-alloy steels

As high alloy steels are referred to, in which at least one alloying element exceeds an average content of 5 percent by mass.

Name:

• High alloy steels are forward characterized by an X, then it follows multiplied by the factor 100 carbon content, followed by the chemical element symbols of the alloying elements in order of decreasing mass fractions, and end up in the same order, separated by hyphens, the mass fractions of the alloying elements listed earlier in weight by weight ( but without multipliers ).

High-speed steels

High-speed steels (abbreviation HS (formerly HSS high speed steel ) ) are characterized by high wear resistance, resistance to tempering and hot hardness up to 600 ° C from. They are used for example as broaches, twist drills, milling cutters, turning tools and inserts.

The carbon content is usually 0.8 to 1.4 %.

Designation according to EN ISO 4957 (tool steels): letters HS and below numbers which indicate the order in W, Mo, V, and Co the mass fractions in whole rounded numbers.

Example: HS2 -10 -1-8

• HS: High Speed ​​Steel
• 2: 2 % W (tungsten)
• 10: 10% Mo (molybdenum)
• 1: 1% V ( vanadium)
• 8: 8% Co ( cobalt)

Sometimes you can still find the term only with S, followed by three to four digits. Only three digits are indicated, no cobalt contained in the high-speed steel:

Example: S6- 5-2

• 6% W (tungsten)
• 5% Mo (molybdenum)
• 2% V ( vanadium)
• 0% Co ( cobalt)

Furthermore, in S6 -5- 2 is still about 4% chromium, which is not apparent from the symbol.

Hardened steels and quenched and tempered steels

The properties of case hardened steel and heat-treated steel are largely defined by their carbon content, and this fact also assigns their nomenclature below.

Here again x is the carbon content in mass percent times 100 ( With a carbon content < 0.25 % of the steel -hardened, about treatable. )

Cast steel

As a cast steel is called steels, which are provided directly to the pouring into their final shape without forming larger.

Name:

• As with the low-alloy steels, but with projecting G.

• Alloyed accordingly:

• Unalloyed similar to steels for mechanical engineering

Material numbers

Material numbers will be issued in Europe by the Steel Institute VDEh.

Title: X.YYZZ (AA) with

• X: Main group
• Y: Species numbers
• Z: counting numbers
• A: Advanced counting numbers when it makes it necessary to increase the number of grades of steel.

The main group X for steel and cast steels is " 1". The variety YY numbers are used for classification, the two counting numbers ZZ be assigned chronologically.

Examples:

1.7218 translates into [ steel ]. [Stainless steel with Cr and < 0.35 mass percent Mo]. [ 0.25 mass percent C, 1.0% Cr, 0.65 % Mn] The nickname would be 25 CrMo 4

Arguably the most well-known material number in the steel industry is the 1.4301, which was associated with the first stainless steel. His short name is X5CrN18 - 10th

After the retracted DIN standard DIN 17007-2:1961-09 the sites were standardized as steel-making techniques 6 and 7 as a treatment condition in addition, usually was but refrained.

A detailed description of the material numbers of all materials is done in a separate article.

Designation according to purpose

• Example: S355J2 N

• Guaranteed notched impact strength:

• Accessories: ( ...) A: precipitation -hardening
• M: Thermo Mechanically treated
• N: Normalized (either annealed or rolled)
• Q: Coated ( quenched )
• H: high-temperature
• L: Low Temperature
• G: Other Features
• Other additives that characterize the intended use, are possible.

• Example: P460M

• N = Normalised or normalized rolled
• M = treated Thermomechanically
• Q = Quenched and tempered

• Example: L360NB

• N = Normalised or normalized rolled
• M = treated Thermomechanically
• Q = Quenched and tempered

• A = steel tubes for lines < 16 bar
• B = steel tubes for cables > 16 bar
• C = steel tubes for exceptional loads

• An example. E235

• Example: H320B

• B = bake-hardening steel
• P = Phosphorlegiert
• X = dual-phase steel
• Y = IF steel ( interstitial free steel )

• Example: DC01

• Cnn = cold rolled, with two-digit code nn
• Dnn = hot-rolled, with two-digit code nn
• Xnn = type of rolling is not required

Furthermore, there are steels whose composition is more important than the minimum yield strength. For this, the composition is specified in accordance with a defined code.

Other names

General is to say that the name of the steels is presently Although clearly defined, but this has changed several times in recent years. Furthermore, there are brand names and historically grown designations (eg St52, V2A, invar, stainless, ...) for certain steels, so that the designation of steels appears to be somewhat confusing in general. In the United States of steel for a system of the American Iron and Steel Institute (AISI ), respectively.