01 Steel Product Processing Condition Symbols
Core Function: Indicate the processing or heat-treatment condition of steel products, reflecting the technological characteristics of the material.
Symbol Rule: The symbol is separated from the preceding designation by a “+”.
Main Symbols and Meanings:
+A: soft annealed
+AC: annealed to achieve spheriodised carbides
+AR: as rolled (without any special rolling and/or heat treatment conditions)
+AT: solution annealed
+C: cold work hardened
+Cnnn: cold work hardened with a minimum tensile strength of nnn MPa
+CPnnn: cold work hardened with a minimum 0.2% proof strength of nnn MPa
+CR: cold rolled
+DC: delivery condition at manufacturer's discretion
+FP: treated to ferritic-pearlite structure and hardness range
+HC: hot rolled followed by cold hardening
+I: isothermically treated
+LC: skin passed (temper rolled or cold drawn)
+M: thermomechanically formed
+N: normalised or normalised formed
+NT: normalised and tempered
+P: precipitation hardened
+Q: quenched
+QA: air quenched
+QO: oil quenched
+QT: quenched and tempered
+QW: water quenched
+RA: recrystallisation annealed
+S: treated for cold shearing
+SR: stress relieved
+T: tempered
+TH: treatment to hardness range
+U: untreated
+WW: warm worked
02 Steel Product Coating and Special Requirement Symbols
Core Function: Indicate special performance requirements of steel products. These requirements usually relate to intrinsic steel properties but, due to practical needs, are treated as part of the product designation.
Symbol Rule: The symbol is separated from the preceding designation by a “+”.
Main Symbols and Meanings:
+CH: core hardenability
+H: hardenability
0: through thickness property; minimum reduction of area= 15 %
0: through thickness property; minimum reduction of area = 25 %
0: through thickness property; minimum reduction of area = 35 %
+A: hot dip aluminium coating
+AS: aluminium silicon alloy coating
+AZ: aluminium zinc alloy(> 50 % Al) coating
+GE: electrolytic chromium/chromium oxide coating (EGGS)
+CU: copper coating
+IC: inorganic coating
+OC: organic coating
+S: hot dip tin coating
+SE: electrolytic tin coating
+T: hot dip lead tin alloy (terne) coating
+TE: electrolytic lead tin alloy (terne) coating
+Z: hot dip zinc (galvanised) coating
+ZA: hot dip zinc aluminium(> 50 % Zn) coating
+ZE: electrolytic zinc coating
+ZF: hot dip zinc iron (galvannealed) coating
+ZN: electrolytic zinc nickel alloy coating
03 Steel Product Selection Examples
Scenario 1: High-Strength Steel Plate for Bridge Structures (with through-thickness properties and corrosion-resistant coating)
Requirement Analysis: Bridge load-bearing structures must withstand vertical loads and environmental corrosion. Steel plates must have good through-thickness mechanical properties (to avoid lamellar tearing) and atmospheric corrosion resistance.
Symbol Selection:
Through-thickness properties, minimum reduction of area 25% → add +Z25
Hot-dip zinc coating for atmospheric corrosion resistance → add +Z
Base Steel Grade: S355J2
Final Designation: S355J2+Z25+Z
Explanation: This grade meets bridge requirements for strength, low-temperature toughness, and through-thickness properties, while zinc coating extends service life in outdoor conditions.
Scenario 2: Automotive Chassis Cold-Stamped Part (with work hardening and phosphating pretreatment)
Requirement Analysis: Automotive chassis components require cold stamping formability. After cold work, the steel must reach the target strength, and the surface must be suitable for subsequent phosphating treatment (requiring a cold-rolled base).
Symbol Selection:
Work hardening with minimum tensile strength 300 MPa → add +C300
Cold-rolled base material → add +CR
Base Steel Grade: DC04 (cold-forming flat steel)
Final Designation: DC04+CR+C300
Explanation: The cold-rolled state (+CR) ensures good stamping formability, while work hardening (+C300) improves strength, meeting both mechanical and processing requirements for chassis parts.
Scenario 3: Chemical Equipment Pressure Pipe (with hardenability and corrosion-resistant coating)
Requirement Analysis: Chemical pipelines carry high-temperature and high-pressure media, requiring uniform hardenability (to ensure consistent mechanical properties) and a corrosion-resistant surface coating against acids and alkalis.
Symbol Selection:
Hardenability requirement → add +H
Electrolytic chromium/chromium oxide coating (for chemical corrosion resistance) → add +CE
Base Steel Grade: 13CrMo4-5
Final Designation: 13CrMo4-5+H+CE
Explanation: The hardenability symbol (+H) ensures uniform wall-thickness properties, while chromium-based coating (+CE) resists aggressive media, making the steel suitable for chemical environments.
Scenario 4: Electrical Steel Sheet for Motor Cores (with annealed condition and no coating)
Requirement Analysis: Motor cores require low iron loss, high magnetic permeability, and annealing to remove stress and stabilize magnetic performance. No surface coating is required to ensure efficient lamination.
Symbol Selection:
Base grade: non-oriented electrical steel 50W400 (iron loss 4.00 W/kg, non-oriented).
Stress-relief annealing → add +A
No coating → no symbol added
Final Designation: 50W400+A
Explanation: Annealing (+A) reduces core loss, while the absence of coating ensures tight lamination, improving motor efficiency.