1 carbon structural steel consists of Q+ digital + quality grade symbol + deoxidation method. The steel dubbed "Q", representing the yield point of steel, behind the digital representation of the yield point value, in units of MPa such as Q235 (s) said the yield point for carbon steel 235MPa. The necessary grades can be marked behind said deoxidation methods of quality grades and symbols. Quality grade symbols are A, B, C, D. Method of deoxidation symbol: F said the boiling steel; B said semi killed steel: Z said killed steel; TZ said special killed steel, steel can not mark, that is, Z and TZ are not standard. Q235-AF, for example, grade a boiling steel. The carbon steel for special purposes, such as steel, marine steel bridge, basically adopt carbon steel structure representation, but added that the final use of steel letters.
Two digits of 2 high quality carbon steel steel at the beginning of the 1 that the carbon content of steel, the average carbon content of the very few that, for example, the average carbon content of 0.45% steel, steel is "45", it is not the order, we can not read No. 45 steel. High quality carbon structural steel with high manganese content should be marked with manganese elements, such as 50Mn. High quality carbon steel, steel, steel and SEMIKILLED boiling for special purposes should be marked in the steel last special, such as the average carbon content of 0.1% semi killed steel, the grade is 10b.
3 carbon tool steel the steel dubbed "T", so as not to be mixed with other steel types. The steel carbon content in the digital representation, to a few thousandths of the average carbon content of the said. For example, "T8" means that the average carbon content is 0.8%. The manganese content is high, in ganghao finally marked "Mn", such as "T8Mn". The high quality carbon steel of phosphorus and sulfur content than the general high quality carbon steel low, in ganghao finally filling the letter "A", to show the difference, such as "T8MnA".
4 free cutting steel the steel dubbed "Y", which is different from the high quality carbon steel. The letter "Y" after the digital representation of the carbon content, the average carbon content of the very few, such as the average carbon content of 0.3% free cutting steel, the steel grade is Y30". The manganese content is high, also in the steel after the mark "Mn", such as "Y40Mn".
The two digit of 5 alloy steel and steel at the beginning of that the carbon content of steel, the average carbon content of the very few, such as 40Cr. The main alloying elements in steel, except for individual micro alloying elements, are generally expressed in a few percent. When the average content of <1.5% alloy steel in general, showing only the element symbol, without showing the content, but often in special circumstances in confusion, symbols also marked with the number "1", such as steel "12CrMoV" and "12Cr1MoV", the chromium content is 0.4-0.6%, after 0.9-1.2%, the remaining components all the same. When the alloy element average content is more than 1.5%, more than 2.5%, more than 3.5%...... When the element symbol should be marked in the content, can be expressed as 2, 3, 4...... Etc.. Such 18Cr2Ni4WA. The steel vanadium V, titanium Ti, AL aluminum, boron and rare earth alloy elements such as B RE, are micro alloying elements, although the content is very low, still should be marked in the steel. For example 20MnVB steel. Vanadium is 0.07-0.12%, boron is 0.001-0.005%. The high-grade steel should be added in the steel "A" at the end, as distinguished from the general quality of steel. The use of special alloy structural steel, steel dubbed (or suffix) on behalf of the steel used symbols. For example, rivet special steel 30CrMnSi steel ML30CrMnSi said.
Methods 6 high strength low alloy steel of steel, alloy structural steel, and basically the same. For the professional use of low alloy high strength steel, steel should be marked in the end. For example, 16Mn steel, special steel for the bridge as "16Mnq", special steel automobile frames as "16MnL", a special pressure vessel steels "16MnR".
7: spring steel spring steel can be classified according to chemical composition of carbon steel and alloy steel spring spring two, representation of its steel, the former is basically the same with the high quality carbon steel, which is basically the same with alloy structural steel.
The 8 steel rolling bearing steel with the letter "G", said rolling bearing steel. The carbon content of high carbon chromium bearing steel steel is not marked, the chromium content in a few thousandths. Such GCr15. Said method of carburizing bearing steel steel and alloy structural steel, basically the same.
9 the average carbon content more than 1% alloy tool steel and high-speed tool steel of alloy tool steel steel, carbon content is not marked; when the average carbon content of <1.0%, with a few thousandths said. For example, Cr12, CrWMn, 9SiCr, 3Cr2W8V. The method of alloying element content in steel is basically the same as that of alloy structural steel. But the steel alloy tool steel in low chromium content, the chromium content in a few thousandths, and the content in said before the number of "0", in order to representation and it generally content according to a few percent of the difference between. Such Cr06. The tool steel high speed steel carbon content is generally not marked, showing only the average content of various alloy elements of a few percent. For example, high-speed steel tungsten steel is expressed as "W18Cr4V". Steel dubbed the letter "C", said its carbon content is higher than the highest "C" common steel.
The carbon content of 10 stainless steel and heat-resistant steel grades 1 said in a few thousandths. For example, the average carbon content of 2Cr13 steel is 0.2%; if the carbon content is less than 0.03% or less than 0.08% contained in the steel, steel before were dubbed "00" and "0", such as 00Cr17Ni14Mo2, 0Cr18Ni9 etc.. The main alloying elements in steel are expressed by a few percent, while the titanium, niobium, zirconium, nitrogen...... Standard Specification for the use of the above alloy structural steel for micro alloying elements