IS 1079 : 2017Hot Rolled Carbon Steel Sheets and Strips

IS 1079:2017 is the specification for hot-rolled carbon steel sheet, strip and coil — the flat steel product used for fabrication, forming, ducting, tanks, enclosures, light structural and general engineering work (and as feedstock for further processing). It is graded by intended use (drawing/forming vs structural vs commercial).

It sits in the steel-materials stack:

• IS 2062 — structural steel plate/section (for *primary structural* use) · IS 1977 — ordinary-quality structural steel
• IS 513 — *cold-rolled* low-carbon sheet (the finer-finish counterpart) · IS 10148 — HR strip for welded tubes · IS 800 — steel design

Hot-rolled sheet/strip is supplied in grades distinguished mainly by formability and strength:

• Drawing/forming grades — higher ductility for bending, pressing, deep-drawing (ducts, enclosures, fabricated components)
• Structural grades — guaranteed strength for light structural/load-bearing fabrication
• Commercial grade — general use where neither tight formability nor guaranteed strength is critical
• Plus thickness/width tolerances, surface condition and (for HR) the characteristic mill scale

The engineering point: the grade must match the function — a commercial grade cracks when deep-drawn; a forming grade may lack the guaranteed strength a light structural member needs. And for primary structural members the correct material is IS 2062 (guaranteed properties/weldability), not a general HR sheet grade — IS 1079 covers a wide quality span and selecting the wrong end of it for the application is the recurring error.

Scenario: fabricated steel items — some formed (ducts/enclosures), some light structural.

Step 1 — classify by function: forming-intensive parts → drawing/forming grade; light structural/load parts → structural grade; non-critical → commercial.

Step 2 — primary structure exception: anything carrying IS 800 design load → IS 2062, not a general HR sheet grade.

Step 3 — specify fully: grade + thickness + tolerance + surface condition; HR carries mill scale (remove for painting/welding-critical surfaces).

Step 4 — verify: mill certificate for grade/properties; check thickness within tolerance (a thin-side coil reduces section capacity).

Step 5 — process accordingly: forming grades for bends/draws; account for scale in welding/coating.

Matching grade to function gives parts that form without cracking and carry their loads; mis-grading gives cracked draws or under-strength members.

1. Using a general HR sheet grade for primary structure. Load-bearing members need IS 2062 guaranteed properties/weldability — not a commercial/forming grade.

2. Wrong grade for forming. Commercial grade cracks on deep draws; specify a drawing/forming grade where formability governs.

3. Ignoring thickness tolerance. Coil on the thin side reduces section capacity — verify against tolerance.

4. Forgetting mill scale. HR surface scale must be removed for paint adhesion/critical welds.

5. Confusing HR with CR sheet. IS 513 cold-rolled is the finer-finish/closer-tolerance product — different applications.

• IS 2062 — structural steel (primary load-bearing) · IS 1977 — ordinary-quality structural steel
• IS 513 — cold-rolled low-carbon sheet (finer counterpart) · IS 10148 — HR strip for welded tubes
• IS 800 — steel design · IS 1608 Part 1 — tensile test (grade verification)

IS 1079 is current (2017) and covers a wide quality span of hot-rolled flat steel — from deep-drawing formability grades to light structural grades to commercial — and the recurring error is selecting the wrong end of that span for the job: a commercial grade that cracks when formed, or a general sheet grade used where guaranteed structural properties were needed. Two disciplines matter: match the grade to the function (formability vs strength), and remember that primary structural members belong to IS 2062, not a general HR sheet grade. Specify grade + thickness + tolerance + surface fully, verify the mill certificate and thickness, and account for HR mill scale in coating/welding. It is an unglamorous material spec whose whole value lies in picking the right grade for the use.