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Basic Knowledge of Steel – Steel Grades and Naming I. Common Japanese grades for steel plates used in general purposes and mechanical structures 1. In the grades of Japanese steel (JIS series), ordinary structural steel is primarily composed of three parts; the first part indicates the material type – for example, S (Steel) denotes steel, while F (Ferrum) denotes iron； The second part indicates different shapes, types, and uses; for example, P (Plate) denotes a plate, T (Tube) denotes a tube, and K (Kogu) denotes a tool ； The third part indicates the characteristic value, usually the minimum tensile strength. For example: SS400 – the first S stands for Steel, the second S stands for Structure; 400 represents the minimum tensile strength of 400 MPa, indicating that it is a common structural steel with a tensile strength of 400 MPa. 2. SPHC – The first letter S stands for Steel, P stands for Plate, H stands for Heat, and C stands for Commercial; together, this term refers to hot-rolled steel plates and strips that are commonly used. 3、SPHD--refers to hot-rolled steel plates and strips for stamping. 4. SPHE--refers to hot-rolled steel plates and strips for deep drawing. 5. SPCC – refers to cold-rolled carbon steel sheets and strips that are commonly used; it is equivalent to China’s Q195-215A grade. The third letter, C, is an abbreviation for Cold. It is necessary to ensure that, for tensile testing, the letter T is added at the end of the grade to denote SPCCT. 6. SPCD -- refers to cold-rolled carbon steel sheets and strips for stamping, equivalent to China’s 08AL (13237) high-quality carbon structural steel. 7. SPCE – refers to cold-rolled carbon steel sheets and strips for deep drawing, equivalent to China’s 08AL (5213) deep-drawing steel. To ensure it is not time-sensitive, add N at the end of the grade to get SPCEN. Tempering codes for cold-rolled carbon steel sheets and strips: annealed condition is A, standard tempering is S, 1/8 hard is 8, 1/4 hard is 4, 1/2 hard is 2, and hard is 1. Surface finish code: D for dull finish cold rolling, B for bright finish cold rolling. For example, SPCC-SD denotes general-purpose cold-rolled carbon steel sheets with standard quenching and tempering treatment and a matte finish. For example, SPCCT-SB denotes standard quenching and tempering as well as bright finishing, referring to cold-rolled carbon steel sheets for which mechanical properties must be ensured. 8. The notation for steel grades used in mechanical structures according to JIS is: S + carbon content + letter code (C, CK), where the carbon content is expressed as the intermediate value multiplied by 100; the letter C denotes carbon, while K denotes steel used for carburizing. For example, carbon steel coil S20C has a carbon content of 0.18-0.23%. II. Methods for Designating Silicon Steel Sheet Grades in China and Japan 1. Chinese method of grade designation: (1) Cold-rolled non-oriented silicon steel strips (sheets) Method of designation: DW + iron loss value (the iron loss per unit weight at a magnetic flux peak value of 1.5 T at a frequency of 50 Hz and a sine wave shape). ) times 100 plus times 100 times the thickness value. For example, DW470-50 indicates cold-rolled non-oriented silicon steel with an iron loss of 4.7 W/kg and a thickness of 0.5 mm; the new designation for this type is 50W470. (2) Cold-rolled oriented silicon steel strips (sheets) Designation method: DQ + iron loss value (the iron loss per unit weight at a magnetic flux peak of 1.7 T at a frequency of 50 Hz and a sine wave shape). ) times 100 plus times 100 times the thickness value. Sometimes, adding G after the iron loss value indicates a high magnetic flux density. For example, DQ133-30 indicates a cold-rolled oriented silicon steel strip (sheet) with an iron loss value of 1.33 and a thickness of 0.3 mm; the new model designation is 30Q133. (3) Hot-rolled silicon steel sheets are denoted by DR; they are classified into low-silicon steel (silicon content ≤ 2.8%) and high-silicon steel (silicon content > 2.8%) based on their silicon content. Representation method: DR + 100 times the iron loss value (the iron loss per unit weight when magnetized repeatedly at 50Hz and with a maximum magnetic flux density of 1.5T in a sinusoidal pattern) + 100 times the thickness value. For example, DR510-50 denotes a hot-rolled silicon steel sheet with an iron loss value of 5.1 and a thickness of 0.5 mm. The grades of hot-rolled silicon steel sheets for household appliances are denoted by JDR + iron loss value + thickness value, such as JDR540-50. 2. Japanese grade designation method: (1) Cold-rolled non-oriented silicon steel strips are denoted by the nominal thickness (the value multiplied by 100) + code A + iron loss guarantee value (the value obtained by multiplying the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.5 T by 100). For example, 50A470 denotes a cold-rolled non-oriented silicon steel strip with a thickness of 0.5 mm and an iron loss guarantee value of ≤4.7. (2) Cold-rolled oriented silicon steel strip: Nominal thickness (value multiplied by 100) + code G: indicates ordinary material; P: indicates highly oriented material + iron loss guarantee value (value obtained by multiplying the iron loss at a frequency of 50 Hz and a maximum magnetic flux density of 1.7 T by 100). For example, 30G130 denotes a cold-rolled oriented silicon steel strip with a thickness of 0.3 mm and an iron loss value guaranteed to be ≤1.3. III. Naming Method for Baosteel’s 1550 Cold-rolled Product Grades (I) Naming Method for Cold-rolled Steel Strips Used in Stamping 1. General steel for stamping: BLCB – abbreviation for Baosteel (BAOSTEEL) ； L—Low Carbon ； C—Generally refers to (Commercial). 2. Low-ageing resistance yield steel: BLDB—abbreviation for BAOSTEEL ； L—Low Carbon ； D—For drawing 3. Steel for deep drawing that is not susceptible to aging: BUFD (BUSD) B—Abbreviation for BAOSTEEL ； U—Super (Ultra) ； F—Formability ； D—Drawing 4. Steel for non-ageing deep drawing: BSUFDB—abbreviation for BAOSTEEL ； SU—Ultra+Super ； F—Formability ； D—Drawing (II) Naming method for high-strength cold-rolled steel strip grades used in cold forming: B ××× × × B—abbreviation for BAOSTEEL ； ×××—Minimum yield point value ； ×—It is generally denoted by V, X, Y, and Z. V: High-strength low-alloy steel; no specified requirement for the difference between yield strength and tensile strength. X: The difference between the minimum yield strength and the minimum tensile strength in V is 70 MPa. Y: The difference between the minimum yield strength and the minimum tensile strength in V is 100 MPa. Z: The difference between the minimum yield strength and the minimum tensile strength in V is 140 MPa. × – Control of oxide/sulfide inclusions (K: Killed, fine-grained) ； F: K+ sulfide control ； O: K, F, and others) Examples: B240ZK, B340VK (III) Naming method for cold-rolled steel strip grades resistant to denting B ××× × × B – abbreviation for BAOSTEEL ××× – minimum yield strength value × – method of strengthening (P: strengthening) ； H: Baking hardening) ×—indicated by 1 or 2 (1: ultra-low carbon ； 2: Low carbon) Example: B210P1: High-strength steel for deep drawing ； B250P2: Phosphorus-containing high-strength steel for general machining ； B180H1: Bake-hardening steel for deep drawing.