Description: BBN steel is a well-known steel manufacturer and service provider in China, JIS G3125 SPA-H Weathering Resistant Steel is our superior product, we are favored by customers with high quality, competitive price and excellent service
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JIS G3125 SPA-H Weathering Resistant Steel | Corten Steel Plate & Sheet | Hot Rolled & Cold Rolled
Atmospheric Corrosion Resistant Steel for Rain, Snow, Ice & Fog | Yield ≥345 / ≥335 MPa, Tensile ≥480 / ≥490 MPa | Self-Protecting Dark Brown Oxide Layer | No Painting Required
Self-Protecting PatinaSPA-H resists rain, snow, ice, fog and other meteorological conditions. Its surface forms a dark brown oxide coating that inhibits deeper penetration.
No Painting, Low MaintenanceThe stable patina removes the need for painting and saves the costly rust-prevention maintenance that ordinary carbon steel needs over the years.
Wide Size RangeThickness 0.5–20 mm, width 100–2000 mm, length 100–2000 mm, in hot rolled and cold rolled supply.
01Product Overview & Specifications
JIS G3125 SPA-H is a Japanese Industrial Standard weathering (atmospheric corrosion resistant) steel widely used in air preheaters, economizers, railway carriages, container production, bridge building and construction. SPA-H resists the corrosive effects of rain, snow, ice, fog and other meteorological conditions.
The surface of SPA-H forms a coating of dark brown oxidation which inhibits deeper penetration. Because the patina protects the base metal, SPA-H saves the cost of painting and the costly rust-prevention maintenance that ordinary carbon steel requires over the years.
Item
Specification Details
Steel Grade
JIS G3125 SPA-H Weathering Resistant Steel
Executive Standard
JIS G3125 Hot Rolled Atmospheric Corrosion Resisting Steels for Welded Structure
Product Type
Hot Rolled / Cold Rolled Weathering Steel Plate & Sheet
Thickness
0.5 – 20 mm
Width
100 – 2000 mm
Length
100 – 2000 mm
Delivery Condition
Hot RolledCold RolledNormalizedQuenchedTemperingTMCP
Core Advantage
Atmospheric corrosion resistance; self-forming dark brown protective oxide; no painting and minimal maintenance
Main Application
Air preheater, economizer, railway carriage, containers production, bridge building, construction
MOQ
1 Ton / Negotiable
Certification
MTC, EN 10204 3.1, Third-party inspection supported
Custom Service
Cutting, drilling, welding, milling, machining and steel structure fabrication
02Equivalent & Comparable Grades
SPA-H is the JIS G3125 hot rolled grade for welded atmospheric-corrosion-resistant structures. Comparable weathering grades exist in other major standards, supporting material substitution for international projects.
Standard System
Comparable Grade
Note
JIS G3125 (Japan)
SPA-C
Same standard; thinner / cold-rolled grade mainly for containers and railway carriages
ASTM (USA)
Corten A / A588 Gr.A
Most common Corten / ASTM weathering equivalents
ASTM (USA, legacy)
A242 Type 1
Early-generation high-strength weathering steel
GB/T 4171 (China)
Q355NH / Q355GNH
Chinese weathering steel equivalents
EN 10025-5 (EU)
S355J0WP / S355J2WP
European weathering structural steel
Note: These grades share the same weathering-steel concept but differ in chemistry limits, thickness ranges and test requirements. For critical or long-cycle structures, verify project specifications before cross-standard substitution.
03Chemical Composition (Ladle Analysis)
Cu, Cr and Ni are the key alloying elements that give SPA-H its atmospheric corrosion resistance and its stable dark brown patina. Values below per JIS G3125.
Grade
C ≤
Si
Mn
P
S ≤
Cu
Cr
Ni ≤
SPA-H
0.12
0.25–0.75
0.20–0.50
0.070–0.150
0.040
0.25–0.60
0.30–1.25
0.65
Note: Phosphorus content is intentionally higher than ordinary structural steel (0.070–0.150%). Phosphorus works together with copper and chromium to improve atmospheric corrosion resistance — a defining feature of weathering steels such as SPA-H.
04Mechanical Properties
Tensile requirements for JIS G3125 SPA-H are specified in two thickness brackets (as-delivered condition).
≥ 345 / ≥ 335 MPaYield Strength (ReL)t ≤ 6.0 mm / t > 6.0 mm
≥ 480 / ≥ 490 MPaTensile Strength (Rm)t ≤ 6.0 mm / t > 6.0 mm
≥ 22 / ≥ 15 %Elongation (A)t ≤ 6.0 mm / t > 6.0 mm
Grade
Plate Thickness
Yield Strength
Tensile Strength
Elongation
SPA-H
≤ 6.0 mm
≥ 345 MPa
≥ 480 MPa
≥ 22
SPA-H
> 6.0 mm
≥ 335 MPa
≥ 490 MPa
≥ 15
Note: Heavier plate carries a slightly lower minimum yield strength but a higher minimum tensile strength, and a lower minimum elongation — this is normal for the thickness effect in JIS G3125. Confirm the bracket that matches your design thickness.
05Available Product Forms & Applications
From 0.5 mm cold rolled sheet to 20 mm hot rolled plate, SPA-H covers thin-gauge cladding as well as load-bearing weathering structures — all cut to your size.
1
SPA-H Hot Rolled Plate
The standard supply form for bridges, buildings and welded structures exposed to the atmosphere.
2
SPA-H Cold Rolled Sheet
Thin gauge from 0.5 mm, with a smooth surface for containers, railway carriage panels and cladding.
3
SPA-H Cut-to-Size Plate
Any size within 100–2000 mm width and length, cut to your drawings to cut your scrap cost.
4
SPA-H Fabricated Parts
Drilled, welded and machined components delivered ready for assembly on site.
Application Field
Typical Use of SPA-H
Power & Boiler
Air preheater, economizer components
Railway & Transport
Railway carriage / wagon body panels
Shipping & Logistics
Container production, freight structures
Bridge & Infrastructure
Bridge building, weathering-exposed structures
Building & Construction
Building cladding, structural frames, facades
Note: The forms above reflect the standard plate and sheet supply range. Other forms can be reviewed against your drawings — send us your requirements and we will confirm feasibility.
06Processing Service, Supply & FAQ
With a full deep-processing center and a dedicated logistics team, we deliver SPA-H cut-to-size and fabricated, on a fast and reliable schedule.
1
Cutting
Any size, any shape — plasma, flame and laser cutting to your drawings.
2
Drilling & Milling
Precision drilling, milling and machining for ready-to-assemble parts.
3
Welding
Expert welding and steel-structure fabrication per client specification.
4
Fast Logistics
Dedicated logistics team for fast delivery time and safe shipment worldwide.
Thickness 0.5–20 mm, width & length 100–2000 mm, cut to any size
Hot rolled, cold rolled, normalized, quenched, tempered and TMCP delivery conditions
Any quantity supported — from sample lots to full project volumes
High-quality logistics team ensuring fast delivery and reliable shipment
Q1Why is SPA-H called a weathering steel?
SPA-H resists the corrosive effects of rain, snow, ice, fog and other meteorological conditions. Its surface forms a coating of dark brown oxidation that inhibits deeper penetration, so the steel protects itself instead of corroding through.
Q2Does SPA-H really not need painting?
In normal atmospheric exposure the patina is the protection, and SPA-H saves the cost of painting and costly rust-prevention maintenance over the years. For aggressive environments or a specific architectural finish, painting or coating can still be applied — we can supply primed or uncoated as requested.
Q3What is the difference between SPA-H and SPA-C?
Both belong to JIS G3125. SPA-H is the hot rolled grade normally supplied as plate and sheet up to 20 mm for heavier welded structures such as bridges and buildings; SPA-C is the thinner / cold-rolled grade mainly used for containers and railway carriages. Their chemistry is the same.
Q4What sizes and delivery conditions can you supply?
Thickness 0.5–20 mm, width 100–2000 mm, length 100–2000 mm. Delivery conditions include hot rolled, cold rolled, normalized, quenched, tempered and TMCP. Send us your dimensions and quantity for a stock-based quotation.
Get Your JIS G3125 SPA-H Steel Official Quotation
Send us your product form, dimensions (or part drawings), quantity and processing requirements. We will reply with the latest stock status, competitive wholesale price and complete certification documents within 24 hours.
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