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JIS G3106 Hot Rolled for Welded Structure SM400A Steel

SM400A Steel is a material designation defined in JIS G3106 standard, SM400A Steel is a Hot Rolled Steel for Welded Structure.

What is SM400A Steel?
SM400A STEEL is hot rolled steel for welded structure in the form of plates, sheets & strips for architecture, engineering structures. SM400A 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 SM400A steel is less reliable in its tensile strength than SM490 steel.

Dimensional Characteristics of SM400A steel:
The applicable thickness for this SM400A steel material as defined in the JIS G3106, it is from 6 mm to 300 mm.

The Chemical Composition of SM400A Steels:
JIS G3106 defines the percentage of chemical composition of SM400A steels as under:
Maximum Carbon (C) percentage is 0.23.
Maximum Manganese (Mn) percentage is 2.5 times of actual percentage of Carbon.
Maximum percentage of Phosphorous (P) is 0.035.
Maximum percentage of Sulphur (S) is 0.035.
Maximum percentage of Silicon (Si) is not mentioned.
Remaining is iron (Fe) percentage and with few negligible impurities.


Mechanical Properties of SM400A Steels:
The tensile strength of the SM400A 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 SM400A Steel varies with the ranges of thickness. The minimum percentage range for elongation is 18.

SM490A comparison with this grade of SM400A Steel material will show how SM400A differs with SM490A in chemical composition & mechanical properties.


Applications of this kind of steel are in making architecture, engineering structures, and in manufacturing of angles, rods and frames.


Engineer Ali Alvi is an industrial engineer who has post graduated from the NED University, then completed his Masters in Industrial Engineering from the University of Ontario. He has also served as an engineer in International Steel Ltd as A Cold rolling mill engineer.

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