Product introduction

JIS G3106 SM490 is a high-strength structural steel formulated according to the Japanese Industrial Standard (JIS), which is widely used in bridges, buildings, ships and vehicle manufacturing. SM490 is a specific steel grade in the JIS G3106 specification, where "SM" stands for "Structural Metal" and "490" means that its minimum tensile strength is 490 MPa. Its main components include carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), etc. The carbon content usually does not exceed 0.20%, and it has good weldability and high tensile strength (490 MPa level).

Product Characteristics

SM490A JISG3106 SM490 Chemical Composition

Chemical composition % max
Grade	TH(MM)	C	Si	Mn	P	S
SM490A	≤50	0.20_	0.55	1.65	0.035	0.035
SM490A	>50≤200	0.22	0.55	1.65	0.035	0.035

JIS G3106 SM490A Low-alloy High-strength Steel Plate Mechanical Property

SM490A Mechanical properties min
Yield strength (N/mm2)						Tensile strength (N/mm2)		Elongation %
≤16	>16-40	>40-75	>75-100	>100-160	>160-200	≤100	>100-200	≤15	>5-16	>16-50	>40
325	315	295	295	285	275	490~610	490~610	≥22	≥17	≥21	≥23

Product features

High Strength Performance
The tensile strength of JIS G3106 SM490 steel can reach a minimum of 490 MPa, and the yield strength is between 325-365 MPa (varies according to different thicknesses), which is higher than ordinary structural steel (such as Q235, whose tensile strength is only 375-500 MPa). This high strength is due to the hot rolling process, which controls the rolling process of steel at high temperature to make the internal grains smaller and more tightly arranged, which is similar to repeatedly kneading dough to enhance toughness and elasticity. Through this design and process, SM490 can effectively reduce the problem of fracture or deformation caused by insufficient material strength.

Good Welding Performance
The tensile strength of JIS G3106 SM490 steel can still reach more than 470 MPa during welding, and the welding is well fused and has no obvious cracks. This is because sulfur and phosphorus are the main impurity elements that are prone to thermal cracking during welding, and the sulfur content of A516 Gr 70 is less than 0.035% and the phosphorus content is less than 0.04%, which greatly reduces the possibility of cracking during welding. This performance is particularly suitable for welding pressure equipment with complex structures, such as multi-layer tank welding, which can ensure that the weld and the parent material have consistent strength, thereby ensuring the overall reliability of the equipment.

Corrosion Resistance
In a salt spray environment, the corrosion resistance life of SM490 after coating exceeds 1,000 hours, while that of ordinary steel is about 700 hours. Its corrosion resistance comes from low sulfur and phosphorus content and surface treatment processes (such as sandblasting and coating). Low sulfur and phosphorus content (≤0.035%) reduces the inclusions precipitated in the steel plate, which are easy to form corrosion points in the corrosive medium, thereby effectively improving the corrosion resistance. In addition, sandblasting can remove the oxide scale and impurities on the surface, so that the coating can be more evenly attached to the surface of the steel plate; the coating further extends the corrosion cycle of the steel plate by isolating oxygen and moisture. This performance is particularly suitable for chemical storage tanks and marine engineering equipment. For example, in storage tanks in coastal environments, the corrosion cycle is extended by 1.5 times that of ordinary carbon steel, which greatly reduces the maintenance frequency and cost of the equipment and improves economic benefits.

FAQs

Q: What is JIS G3106 SM490?

A: JIS G3106 is a specification for high-strength steel for welded structures defined in the Japanese Industrial Standards, of which SM490 is a steel grade in this standard, representing high-strength steel with a tensile strength between 490-610 MPa.

Q: What is the chemical composition of SM490?

A: The main components of SM490 are carbon (C) ≤ 0.18%, manganese (Mn) ≤ 1.60%, silicon (Si) ≤ 0.55%, and phosphorus (P) and sulfur (S) ≤ 0.035% each.

Q: What are the mechanical properties of SM490?

A: The tensile strength of SM490 is 490-610 MPa, and the yield strength is ≥ 325 MPa (applicable to thickness ≤ 16 mm), which decreases with increasing thickness. Its elongation (tensile test in 200 mm specimen) is ≥ 17% (thickness ≤ 16 mm).

Q: What are the uses of SM490?

A: SM490 is often used in construction engineering, bridge manufacturing, shipbuilding and mechanical processing. For example, frame supports of high-rise buildings in construction engineering usually use SM490 steel to ensure strength, and its excellent tensile properties are used in bridge manufacturing to build long-span bridges.

Q: How is the welding performance of SM490?

A: SM490 has excellent welding performance and is suitable for a variety of welding methods, including manual welding (SMAW), gas shielded welding (GMAW) and submerged arc welding (SAW). The low carbon content reduces the risk of weld cracks, and the tensile strength of its welded joints is usually comparable to that of the parent material. For example, in the gas shielded welding process, the incidence of weld cracks is less than 5%, which greatly improves welding reliability.

Q: What is the standard thickness range of SM490?

A: According to JIS G3106, the standard thickness range of SM490 steel is usually between 6 mm and 50 mm. For example, SM490 steel plates used for bridge structures are usually 20 mm thick, while steel used for building frames is mostly 10 mm to 25 mm, which can be processed according to specific needs.

Q: How is the corrosion resistance of SM490?

A: SM490 has good corrosion resistance in general atmospheric environments, but requires additional protection measures such as spraying anti-corrosion coating or galvanizing in high humidity, salt spray or chemical corrosion environments. SM490 steel that has been treated with anti-corrosion treatment can maintain no obvious corrosion for more than 500 hours in salt spray tests.

Q: What is the price of SM490?

A: The price of SM490 steel fluctuates according to specifications, quantity and market demand. Taking the market price in 2024 as an example, the average price of SM490 steel plate is around 5,000-6,000 yuan/ton, which is slightly higher than ordinary carbon steel (such as Q235, about 4,000 yuan/ton), but considering its higher strength and longer service life, the overall cost-effectiveness advantage is significant.

Q: How is the fatigue performance of SM490?

A: SM490 shows extremely high durability in fatigue tests. Experiments show that when the number of load cycles exceeds 10^6 times, its fatigue limit remains at around 220 MPa, which is nearly 50% higher than Q235 steel. This makes it suitable for structures with large dynamic loads, such as large robotic arms or bridge suspension structures.

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