What is the yield strength of Mild Steel Grade I?

250 N/mm² for bars up to 20mm diameter, as per Table 2.

Is IS 432 used for modern TMT bars?

No, High Strength Deformed (HYSD) and TMT bars are covered under IS 1786. IS 432 is strictly for plain mild steel and medium tensile bars.

What is the standard tolerance on weight for a 12mm mild steel bar?

±5% for bars over 10mm up to 16mm diameter, specified in Clause 9.

IS 432 Part 1

: 1982

Mild Steel and Medium Tensile Steel Bars and Hard-Drawn Steel Wire for Concrete Reinforcement - Part 1: Mild Steel and Medium Tensile Steel Bars

CurrentRareSpecificationStructural Engineering · Steel and Reinforcement

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This code specifies the manufacturing, chemical, and mechanical requirements for mild steel (Grade I and II) and medium tensile steel bars used as concrete reinforcement. While largely superseded in everyday practice by deformed TMT bars (IS 1786), it remains the active specification for plain Fe 250 reinforcement bars.

Specifies requirements for mild steel and medium tensile steel bars used as reinforcement in concrete, commonly superseded by IS 1786 for new designs.

Quick Reference Values

yield stress mild steel grade 1250 N/mm² (up to 20mm dia)

yield stress mild steel grade 2225 N/mm² (up to 20mm dia)

yield stress medium tensile steel350 N/mm² (up to 16mm dia)

mass tolerance upto 10mm±7%

mass tolerance 10mm to 16mm±5%

mass tolerance over 16mm±3%

Practical Notes

Mild steel (Fe 250) plain bars are rarely used as main reinforcement in modern structural concrete, but they are still preferred for lifting hooks, dowel bars, and ties where high ductility and bendability are required.

Engineers must check the rolling tolerances on mass per meter during site material testing, as negative mass deviations beyond the permissible limit compromise the cross-sectional area.