JIS G3106 Hot Rolled for Welded Structure SM400B Steel

SM400B Steel is a material designation defined in JIS G3106 standard, SM400B Steel is a Hot Rolled Steel for Welded Structure.

What is SM400B Steel?   

SM400B Steel is hot rolled steel for welded structure in the form of plates, sheets & strips for architecture, engineering structures. SM400B steel is a material grade and designation defined in JIS G3106 standard. JIS G3106 is a Japanese material standard for hot rolled steel for welded structure steel plates, sheets, strips for Architecture, Engineering Structures.

The hot rolled steel for welded structure SM400B steel is less reliable in its tensile strength than SM490B steel.

Dimensional Characteristics of SM400B steel:

The applicable thickness for this SM400B steel material as defined in the JIS G3106, it is from 6 mm to 300 mm.

The Chemical Composition of SM400B Steels:

JIS G3106 defines the percentage of chemical composition of SM400B steels as under:

Maximum Carbon (C) percentage is 0.20.

Maximum Manganese (Mn) percentage is 1.5 and starts from 0.6 percent.

Maximum percentage of Phosphorous (P) is 0.035.

Maximum percentage of Sulphur (S) is 0.035.

Maximum percentage of Silicon (Si) is 0.35.

Remaining is iron (Fe) percentage and with few negligible impurities.


Mechanical Properties of SM400B Steels:

The tensile strength of the SM400B Steels is expressed in Newton per millimeters and it must be at-least 400 N/mm2 (MPa) and maximum can be 510 N/mm2 (MPa). The yield strength is minimum 245. The elongation property of SM400B Steel varies with the ranges of thickness.  The minimum percentage range for elongation is 18.

SM490B comparison with this grade of SM400B Steel material will show how SM400B differs with SM490B in chemical composition & mechanical properties.


Applications of this kind of steel are in making ship building, engineering structures, and in manufacturing of highly specialized equipment. 

Leave a Reply