SM material: Rolled steel for welded structures, JIS G3106 [SM490 material]

Hello,

I would like to briefly explain about JIS G 3106 rolled steel for welded structures, specifically SM material. Rolled steel for welded structures can be considered as a JIS standard product that serves as the basis for Kumagai’s main product, high-tensile steel plates.

What is JIS standard?

The Japanese Industrial Standards (JIS) are national standards in Japan that define criteria for the quality, performance, and safety of products and services.

These standards are applied across various fields, ranging from industrial products to daily necessities and services, playing a crucial role in ensuring the reliability and compatibility of products.The JIS standards for steel products specify in detail the chemical composition, mechanical properties, dimensions and shapes, and test methods of the steel.

These standards play a crucial role in ensuring the reliability and compatibility of the products. Steel products are used in a wide range of industries, including construction, manufacturing, automotive, and shipbuilding. By adhering to JIS standards, domestic and international trade and imports/exports can proceed smoothly.

This ensures improved product quality and safety, providing peace of mind to consumers and businesses.

What is JIS G3106 [SM490 material]?

While JIS G 3101 (General structural rolled steel, commonly known as SS material) does not consider weldability,JIS G 3106 (Rolled steel for welded structures) specifies hot-rolled steel and hot-extruded shapes used in bridges, ships, vehicles, oil storage tanks, containers, and other welded structures, with particularly excellent weldability (quoted from JIS Handbook). It applies to a variety of types, including thick plates, coils, and shapes.

Various types of steel materials

In JIS, there are 11 types of steel materials:

• SM400A, SM400B, SM400C
• SM490A, SM490B, SM490C
• SM490YA, SM490YB
• SM520B, SM520C
• SM570

They are classified based on their yield point or proof stress (N/mm²) and tensile strength (N/mm²).

The numerical value in the designation (e.g., the “400” in SM400) represents the minimum guaranteed tensile strength. Therefore, for SM490, the material guarantees a tensile strength of 490 N/mm².

In general, the larger the number, the harder and stronger the material is, and the more load it can withstand.

What do the letters A, B, and C after the numbers mean?

This indicates the grade differences for each type.

Low: A → B → C : High

The higher the grade, the further it progresses from A to C.

The primary indication of the grade is reflected in the difference in Charpy absorption energy (J).The higher the value of this Charpy absorption energy, the stronger the steel material is in terms of impact resistance.

types	Testing Temperature　（℃）	Charpy Absorption Energy（J）
SM400B	0	27≦
SM400C	0	47≦
SM490B	0	27≦
SM490C	0	47≦
SM490YB	0	27≦
SM520B	0	27≦
SM520C	0	47≦
SM570	-5	47≦

No impact resistance guarantee for [A]

The ones marked with ‘B’ guarantee a Charpy absorption energy of 27J or more. The ones marked with ‘C’ guarantee a Charpy absorption energy of 47J or more. This means that the ones marked with ‘C’ are stronger in terms of impact resistance.

By the way, the setting of 47J for Charpy absorption energy is related to fracture investigation in low-temperature environments (such as cold regions and ships) and is also a notable value for use in low-temperature conditions.

Contact us

We handle JIS G3106 SM materials. Please feel free to contact us.

Please email us at the following address!!↓↓↓

info@kumagai-steel.co.jp