What Is Q460DR Steel Plate?
Q460DR is a high-strength low-alloy structural steel plate specially designed for low-temperature pressure vessels. The designation follows the Chinese naming convention: Q is the first letter of the pinyin for yield strength, 460 is the minimum lower yield strength of 460 MPa, and DR identifies the special grade for low-temperature pressure vessel service. The plate is governed by the Chinese national standard GB/T 713.3-2023, implemented in March 2024, and is often compared with the European grade P460NL1 of EN 10028-3, which has a similar strength and toughness concept.
Chemical Composition
The typical chemical composition of Q460DR is controlled to balance strength, low-temperature toughness, and weldability. Range or maximum values (percent by mass) include carbon 0.12-0.20, silicon 0.15-0.50, manganese 1.30-1.70, nickel 0.40-0.80, vanadium 0.10-0.20, niobium 0.015-0.050, nitrogen 0.025 maximum, and sulfur 0.008 maximum. The nickel addition provides low-temperature toughness, vanadium and niobium refine the grain structure and raise strength, and the tight sulfur and nitrogen limits protect the impact properties and weldability. The phosphorus limit is also specified in the standard and should be confirmed on the mill certificate.
Mechanical Properties
The mechanical requirements for Q460DR are a minimum lower yield strength of 460 MPa and a tensile strength of 630-730 MPa, with the exact values influenced by plate thickness. For plate in the 6-20 mm thickness range, the minimum elongation is 18%. The key low-temperature requirement is the Charpy impact test at -40 deg C, with an impact absorption energy of at least 60 J, which ensures that the plate retains toughness in low-temperature service and resists brittle fracture under pressure and thermal stress.
Applications
Q460DR is mainly used in the manufacture of low-temperature pressure vessels that must withstand high-pressure loads in low-temperature environments, for example in the petrochemical industry, power stations, and engineering machinery. Typical components include low-temperature storage tanks, process vessels, and pressure-retaining equipment where the combination of high strength and guaranteed toughness at -40 deg C allows lighter walls than ordinary carbon steel grades while maintaining safety margins.
Delivery Condition and Inspection
Q460DR plate is supplied in the normalized or normalized plus tempered condition, which develops the fine-grained microstructure required for the specified strength and toughness. Non-destructive testing, such as ultrasonic examination, is applied to the plate as required by the standard, and the acceptance criteria, including the ultrasonic testing scope and impact testing frequency, should be confirmed against GB/T 713.3-2023 and the purchase specification. The mill certificate records the heat analysis and mechanical test results for traceability.
Frequently Asked Questions
What does Q460DR stand for? Q is the pinyin initial for yield strength, 460 is the minimum yield strength of 460 MPa, and DR marks the low-temperature pressure vessel grade.
Which standard covers Q460DR? GB/T 713.3-2023, the Chinese national standard for low-temperature pressure vessel steel plates, implemented in March 2024.
What is the European equivalent of Q460DR? EN 10028-3 P460NL1 is the closest European grade by strength and low-temperature toughness concept; substitution requires verification of the exact acceptance criteria.
What toughness does Q460DR guarantee? Charpy impact testing at -40 deg C with a minimum impact absorption energy of 60 J.
Can Q460DR be welded? Yes, the grade is designed for welded pressure vessel construction with stable welded joints, using qualified procedures and low-hydrogen consumables as required by the design code.
In which condition is Q460DR delivered? Normalized or normalized plus tempered, to develop the required grain structure and mechanical properties.
Is Q460DR suitable for high-pressure low-temperature service? Yes, it is intended for pressure vessels that combine high pressure with low-temperature service, such as petrochemical and power plant equipment.
