SPHC steel: properties, composition, equivalents

SPHC is the commercial grade of JIS G3131 hot-rolled mild steel sheet: no guaranteed yield, tensile ≥ 270 MPa, elongation 27–31 %. Full G3131 family, EN 10111 (DD11–DD13) and ASTM A1011 equivalents, and how to read the P/H/C letters.

What is SPHC?

SPHC is the workhorse hot-rolled sheet of Japanese and wider East Asian practice, and the grade most often written on an enquiry that simply means *ordinary hot-rolled coil*. The letters decode as Steel Plate Hot Commercial: JIS G3131 covers three grades in one family — SPHC for commercial use, SPHD for drawing and SPHE for deep drawing — separated by how clean the steel is and how far it will stretch before it tears.

What matters when reading a G3131 certificate is what is *not* there. No yield strength is guaranteed, no impact energy, no carbon equivalent. The standard fixes a minimum tensile strength of 270 MPa, an elongation band and four chemical limits, and nothing else. That is entirely adequate for a bracket, a duct or a pressed panel, and entirely inadequate for a structural member — which is why substituting SPHC for SS400 or S235JR is a specification error, even though the plates look identical.

The practical range is 1.2 to 14 mm; below that the product becomes cold-rolled SPCC and above it hot-rolled plate. Pickled and oiled material carries the suffix P and is what a press shop or a laser cutter should be ordering, because mill scale interferes with both.

SPHC chemical composition

SPHC, SPHD and SPHE share one chemistry table in G3131 with the limits tightening down the list: SPHD is C ≤ 0.10, Mn ≤ 0.50, and SPHE is C ≤ 0.10, Mn ≤ 0.50 with P ≤ 0.030 and S ≤ 0.035. Nothing else is specified — this is a plain low-carbon steel.

SPHC mechanical properties

Elongation depends on thickness: the lower figure applies at 1.2–1.6 mm, the higher above 3.2 mm. No yield strength is guaranteed in any of the three grades — typical values run 210–280 MPa.

Impact toughness

SPHC requires a minimum Charpy V-notch energy of 0 J at °C. No impact requirement. G3131 is a forming standard, not a structural one; if a project needs notch toughness, the structural grades of JIS G3106 (SM400, SM490) or EN 10025-2 apply.

SPHC equivalent grades

Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for SPHC →

Old and superseded designations

Product forms and tolerance standards

Product forms: hot-rolled coil (1.2–14 mm, dominant), cut sheet, slit strip, pickled and oiled (SPHC-P).

Dimensional tolerances: Thickness and width to JIS G3193; the pickled variant carries the suffix P (SPHC-P). Ordinary, cut-edge and mill-edge widths are all covered..

Key property values

SPHC tensile strength

≥ 270 MPa minimum, typically 300–380 MPa in practice. No maximum is specified, which is the main difference from EN 10111, where DD11 is capped at 440 MPa.

Yield strength

Not specified. Typical values are 210–280 MPa. If a design needs a guaranteed yield, the grade is wrong: use SS400 (245 MPa) from JIS G3101 or S235JR from EN 10025-2.

Elongation

SPHC 27 % at 1.2–1.6 mm rising to 31 % above 3.2 mm; SPHD 30–36 %; SPHE 31–39 %. The elongation band is the real difference between the three grades.

Thickness range

1.2 to 14 mm as coil, sheet and strip. The pickled variant SPHC-P is normal above 2 mm for parts that will be welded, painted or laser cut.

Surface

As-rolled with mill scale, or pickled and oiled (P). There is no surface class system comparable to the A/B classes of EN 10130 — surface expectations are agreed between buyer and mill.

Weldability

Welds without difficulty by every common process. Carbon is capped at 0.15 % and manganese at 0.60 %, so the carbon equivalent sits around 0.25 and neither preheat nor post-weld heat treatment is needed at any thickness in the range. Mill scale should be removed from the weld zone on as-rolled material; on pickled sheet the surface is ready. Spot, MAG and laser welding are all routine, and the grade is used in exhaust, chassis and enclosure fabrication precisely because it is so tolerant.

Machining, forming and heat treatment

Soft and gummy rather than hard: 100–120 HB, prone to built-up edge at low speeds. Use positive-rake tooling and higher cutting speeds than the hardness suggests. Punching, shearing and roll forming are all straightforward; the low carbon means cut edges stay ductile and can be bent without cracking.

Typical applications

• Pressed and formed parts: brackets, housings, covers
• Automotive chassis components, wheel rims and exhaust parts
• Welded tube and pipe as feedstock
• Ducting, enclosures and general fabrication
• Drums, containers and light tanks
• Substrate for pickling, galvanizing and further processing

Frequently asked questions

Related grades

Verified against JIS G3131:2018; JIS G3131:2018 Tables 2 and 3; EN 10111:2008 (for the equivalence); ASTM A1011/A1011M. Last checked: September 2026.