What Is SS540 Steel
SS540 is a structural hot-rolled steel grade defined in JIS G3101, the Japanese material standard for hot-rolled steel plates, sheets, and strips for general structural applications. The designation "SS" stands for structural steel, and "540" refers to the minimum tensile strength of 540 N/mm² (MPa). The grade is used in the form of plates, sheets, and strips where higher strength is required than that offered by SS400 or SS490.
Chemical Composition Requirements
JIS G3101 sets the chemical limits for SS540 primarily on phosphorus and sulfur, which are each limited to a maximum of 0.050%. The standard does not impose minimum carbon or manganese requirements for the grade, which gives the steelmaker flexibility in balancing strength, weldability, and cost. Buyers should note that the chemical limits in JIS G3101 differ from those of ASTM A572, and the two standards should not be mixed when writing purchase specifications.
Mechanical Properties
SS540 provides a minimum yield strength of about 400 MPa and a minimum tensile strength of 540 MPa. Compared with SS400, which has a minimum yield strength of 245 MPa and a tensile strength range of 400–510 MPa, SS540 offers significantly higher strength for the same cross-section, which is why it is selected for applications where strength matters but weight is a concern. The exact yield point, tensile strength, and elongation values depend on plate thickness and should be confirmed against the latest edition of JIS G3101.
SS540 Equivalent Grades
Commonly listed equivalents for SS540 include DIN 17102 STE 380 in the German system, NFA 36201 E 375R in the French system, MNC 810E SS21,42,01, CSA G40-21 400W and 400WT in the Canadian system, and ASTM A572 Grade 60 and Grade 65 in the American system. These grades are similar in strength level but are not identical in chemistry and testing requirements, so each equivalent should be verified against the relevant national standard before substitution is approved for a project.
Typical Applications
Because of its higher strength and minimum yield strength above 400 MPa, SS540 steel plate is widely used in general buildings, plant construction, and all kinds of construction machinery, including mines and various types of drilling rigs, power shovels, hydraulic supports, and coal mining machinery and equipment. It is also suitable for other structures where a high strength-to-weight ratio is required.
Frequently Asked Questions
What grade of steel is SS540? SS540 is a structural hot-rolled steel grade defined under JIS G3101, distinguished by a minimum tensile strength of 540 N/mm² (MPa). The material is commonly supplied in thickness ranges from 6 mm to 120 mm with robust mechanical properties.
What is the difference between SS400 and SS540? Compared with SS400 and SS490, SS540 has much higher strength, with a minimum yield strength of about 400 MPa and a minimum tensile strength of 540 MPa. The higher strength makes it popular for applications where strength is needed but weight is an issue.
What is the steel equivalent of SS540? Commonly listed equivalents are DIN 17102 STE 380, NFA 36201 E 375R, MNC 810E SS21,42,01, CSA G40-21 400W and 400WT, and ASTM A572 Grade 60 and Grade 65.
Is SS540 weldable? Yes. As a structural carbon steel grade, SS540 can be welded with conventional processes, although the higher strength of the grade should be considered when selecting filler materials and welding parameters.
Which standard defines SS540? SS540 is defined in JIS G3101, the Japanese standard for hot-rolled steel plates, sheets, and strips for general structural usage.
Can SS540 be used outdoors? SS540 is not a weathering steel and does not have the corrosion resistance of atmospheric corrosion-resistant grades; for unprotected outdoor service, protective coating or the use of weathering steel should be considered.
