What Is Q265GNH Weathering Steel?
Q265GNH is a weathering steel grade specified in the Chinese standard GB/T 4171, and it is commonly referred to in the market as Q265GNH weathering steel or Q265GNH corten steel. The designation indicates a minimum yield strength of 265 MPa, with GNH identifying the atmospheric corrosion resistant grade with enhanced mechanical properties compared with the Q235NH class. Because of its alloying additions, Q265GNH forms a stable patina in atmospheric exposure and can be used unpainted in many outdoor applications, reducing the need for coating maintenance.
Chemical Composition
The typical chemical composition of Q265GNH per GB/T 4171 is carbon 0.12% maximum, silicon 0.10-0.40%, manganese 0.20-0.50%, phosphorus 0.07-0.12%, and sulfur 0.02% maximum, together with controlled additions of copper, chromium, and nickel that provide the atmospheric corrosion resistance. The relatively high phosphorus range contributes to the corrosion-resistant oxide layer, and the tight sulfur limit protects weldability and toughness. The exact limits should be confirmed against the applicable edition of GB/T 4171 and the mill certificate.
Mechanical Properties
Q265GNH has a minimum yield strength of 265 MPa and a minimum tensile strength of 410 MPa per GB/T 4171, with elongation requirements specified in the standard. This strength level is higher than Q235NH and supports structural members in vehicles, bridges, towers, and containers with efficient material use. Mechanical test results should be confirmed on the mill certificate for the ordered thickness.
Typical Applications
Q265GNH steel is mainly used for railways, vehicles, bridges, and towers, where the combination of strength and atmospheric corrosion resistance extends service life in outdoor service. It is also used for containers, oil derricks, harbor construction, and general outdoor steel structures. In all these applications, the plate can serve unpainted in suitable atmospheric environments, and the natural rust-colored surface is often accepted as a design feature in architectural work.
Specification and Additional Conditions
Q235NH and Q265GNH plates are commonly available in thicknesses from 1 to 100 mm, widths from 1000 to 4100 mm, and lengths from 1000 to 12000 mm, subject to mill capability. Additional conditions that can be specified include ultrasonic examination (UT), as-rolled (AR), thermomechanical controlled processing (TMCP), normalized (N), or quenched and tempered (Q+T) delivery, through-thickness (Z-direction) testing such as Z15, Z25, and Z35, Charpy V-notch impact testing, HIC testing, post-weld heat treatment simulation, third-party inspection, and surface treatments such as shot blasting and painting.
Frequently Asked Questions
Is Q265GNH the same as corten steel? Q265GNH belongs to the weathering steel family and behaves like the historic corten grades, but it is a specific Chinese grade defined by GB/T 4171 with its own composition and property requirements.
What is the yield strength of Q265GNH? The minimum yield strength is 265 MPa per GB/T 4171.
What is the tensile strength of Q265GNH? The minimum tensile strength is 410 MPa per GB/T 4171.
Does Q265GNH need painting? In most atmospheric environments it can be used unpainted because the stable patina protects the surface; coating is recommended in marine or heavily polluted conditions.
Can Q265GNH be welded? Yes, Q265GNH is weldable with standard low-hydrogen processes, and weathering-compatible filler metal should be used so the weld zone weathers at a similar rate.
Where is Q265GNH commonly used? It is used in railways, vehicles, bridges, towers, containers, oil derricks, and harbor construction.
Which sizes are available? Typical supply covers 1-100 mm thickness, 1000-4100 mm width, and 1000-12000 mm length, subject to mill capability.
