9. Alloy tool steel and high-speed tool steel

① When the average carbon content of alloy tool steel grade is ≥ 1.0%, the carbon content is not indicated; When the average carbon content is less than 1.0%, it is expressed in thousandths. For example, Cr12, CrWMn, 9SiCr, 3Cr2W8V.

② The expression method for the content of alloying elements in steel is basically the same as that of alloy structural steel. But for alloy tool steel grades with lower chromium content, the chromium content is expressed in thousandths, and a "0" is added before the number indicating the content to distinguish it from the general element content expressed in percentage. For example, Cr06.

③ The steel grade of high-speed tool steel generally does not indicate the carbon content, but only the average percentage of various alloy elements. For example, the steel grade of tungsten based high-speed steel is represented as "W18Cr4V". Steel grades with the letter "C" indicate that their carbon content is higher than those of general steel grades without the letter "C".

10. Stainless steel and heat-resistant steel

① The carbon content in steel grades is expressed in thousandths. For example, the average carbon content of "2Cr13" steel is 0.2%; If the carbon content in the steel is ≤ 0.03% or ≤ 0.08%, it is indicated by "00" and "0" before the steel grade, such as 00Cr17Ni14Mo2, 0Cr18 Ni9, etc.

② The main alloying elements in steel are expressed in percentage, while titanium, niobium, zirconium, nitrogen, etc. are marked according to the above method for representing microalloyed elements in alloy structural steel.

11. Welding rod steel

Its steel grade is preceded by the letter "H" to distinguish it from other steel classes. For example, stainless steel welding wire "H2Cr13" can be distinguished from stainless steel "2Cr13".

12. Silicon steel for electrical purposes

① The steel grade consists of letters and numbers. The first letter of the steel grade DR represents hot-rolled silicon steel for electrical purposes, DW represents cold-rolled non oriented silicon steel for electrical purposes, and DQ represents cold-rolled oriented silicon steel for electrical purposes.

② The number after the letter represents 100 times the iron loss value (W/kg).

③ Adding the letter "G" to the end of the steel grade indicates that it is inspected at high frequencies; Those without "G" indicate those tested at a frequency of 50 cycles.

For example, steel grade DW470 indicates that the maximum unit weight iron loss of cold rolled non oriented silicon steel products for electrical purposes is 4.7W/kg at a frequency of 50 Hz.

13. Pure iron for electrical purposes

① Its brand consists of the letter "DT" and numbers, where "DT" represents pure iron for electrical purposes and numbers represent the sequential numbers of different brands, such as DT3.

② The letters added after the numbers indicate electromagnetic performance: A - Advanced, E - Super, C - Super, such as DT8A.