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Resources/Materials & grades/1070 / 070A72

Materials & grades

1070 high-carbon steel: equivalents 070A72 (EN42), 70C6, C67S and S70C

1070 is a high-carbon steel with about 0.70 % carbon, used for springs, spring wire, blades and wear parts after hardening and tempering. Its closest equivalents are 070A72 (old EN42) in the UK, 70C6 in India, C67S and C75S (1.1231, 1.1248) in Europe, and S70C or SWRH72A in Japan.

Names by standard

What it is called in each region

RegionSystemDesignationStandardMatch
USAAISI/SAE1070Composition limits shown are SAE J403 (P ≤0.030 %). ASTM A29 and older AISI tables give P ≤0.040 %.SAE J403; ASTM A510 / A576 (10L70) / A713 (wire) / A830Same material
UNSG10700—Same material
UKBS 970070A72Carbon 0.70–0.75 %, manganese 0.60–0.80 %: a narrower carbon range than 1070 (Total Materia).BS 970-1Closest equivalent
BS 970 (1955 EN series)EN42Superseded 1955 name. Roymech ties EN42 to 070A72; Total Materia also uses it for 070A78.—Closest equivalent
BS 1449 / BS 5770CS70Cold-rolled spring strip with carbon 0.65–0.75 %, matching 1070's carbon range (West Yorkshire Steel).BS 5770-2 (withdrawn)Closest equivalent
EUEN 10027-1 nameC67S (1.1231)Cold-rolled strip for springs. Carbon 0.65–0.73 %, with tighter phosphorus and sulphur than 1070.EN 10132-4Closest equivalent
EN 10027-1 nameC75S (1.1248)Cold-rolled strip for springs. Carbon 0.70–0.80 %, the next step up from C67S.EN 10132-4Closest equivalent
EN 10027-1 nameC70D (1.0615)Wire-rod grade listed against 070A72 by Total Materia. Composition limits not tabulated here.EN 10016 / EN ISO 16120 (wire rod)Closest equivalent
DIN (legacy)Ck67 / Ck75Superseded German names for C67S and C75S.—Closest equivalent
IndiaIS 157070C6Carbon 0.65–0.75 %, the same as 1070, with manganese 0.50–0.80 %.IS 1570 (Part 2/Sec 1)Closest equivalent
IS 1570 (old designation)C70Superseded Indian name for 70C6.—Closest equivalent
JapanJIS G 4051S70CCarbon 0.65–0.75 % and manganese 0.60–0.90 %, the same limits as 1070, but offered only as plates, sheets and strips.JIS G 4051 (Annex JB)Equivalent
JIS G 4802S70C-CSPCold-reduced spring strip with carbon 0.65–0.75 %.JIS G 4802Closest equivalent
JIS G 3506SWRH72A / SWRH72BHigh-carbon wire rod for drawing, with carbon 0.69–0.76 % (manganese 0.30–0.60 % for A, 0.60–0.90 % for B).JIS G 3506Closest equivalent

On equivalence

  • No single European grade matches 1070 exactly. EN ISO 683-1 stops at C60, so the nearest are the EN 10132-4 strip grades C67S (0.65–0.73 % C) and C75S (0.70–0.80 % C), each with tighter phosphorus and sulphur and a silicon requirement that 1070 does not have.
  • Do not use the designation C70 for 1070 steel. The material number 1.1520, which some cross-reference lists attach to C70, belongs to a tool steel in a different standard.
  • Sources disagree on EN42. Roymech ties it to 070A72 and Total Materia lists it against 070A78 too, so treat the old EN42 name as covering the 0.70–0.80 % carbon spring range rather than one exact code.
  • In Japan, S70C is in JIS G 4051 only for plates, sheets and strips. For round bar the usual route is the SWRH wire-rod grades or a spring-strip grade in JIS G 4802.
  • Indian 70C6 has the same carbon range as 1070 but lower manganese (0.50–0.80 % against 0.60–0.90 %). IS 1570 fixes only carbon and manganese.

Chemical composition

Composition limits, mass %

Element1070USA · SAE J403070A72UK · BS 970-1 (composition as cited from BS 1429:1980)CS70UK · BS 1449 / BS 5770C67S (1.1231)EU · EN 10132-4C75S (1.1248)EU · EN 10132-470C6India · IS 1570 (Part 2/Sec 1):1979S70CJapan · JIS G 4051 (Annex JB)SWRH72AJapan · JIS G 3506:2024
C0.65–0.750.70–0.750.65–0.750.65–0.730.70–0.800.65–0.750.65–0.750.69–0.76
Si——0.05–0.350.15–0.350.15–0.35—0.15–0.35—
Mn0.60–0.900.60–0.800.50–0.900.60–0.900.60–0.900.50–0.800.60–0.900.30–0.60
P≤0.030≤0.050≤0.045≤0.025≤0.025—≤0.030≤0.030
S≤0.050—≤0.045≤0.025≤0.025—≤0.035—
Cr———≤0.40≤0.40—≤0.20—
Ni———≤0.40≤0.40—≤0.20—
Mo———≤0.10≤0.10———
Cu——————≤0.30—
Cr+Ni——————≤0.35—

Mechanical properties

Strength and hardness

ConditionTensile strengthYield strengthElongationHardness
Hot-rolled bar, estimated minimum (1070)Estimated minimum, SAE J1397 basis; typical values run higher and section size is not statedSAE J1397 estimated minimum values as published by ICAST; typical values run higher and section size is not stated700 MPa102 ksi390 MPa57 ksi12 %—
Annealed and skin passed strip (C67S)Specified maximum, EN 10132-4EN 10132-4 as tabulated by Roymech≤640 MPa≤93 ksi≤510 MPa≤74 ksi≥16 %≤200 HV
Quenched and tempered strip (C67S / C75S)Specified range, EN 10132-4EN 10132-4 as tabulated by Roymech1200–1900 MPa174–276 ksi——370–580 HV

In practice

Behaviour, heat treatment and uses

Characteristics

  • About 0.70 % carbon gives high strength, hardness and spring temper with low ductility; SAE J1397 estimates only about 12 % elongation as hot rolled.
  • Hardenable by oil or water quench and tempered to the strength required; plain carbon steels have low hardenability, so only thin sections harden through.
  • Common in strip and wire form: EN 10132-4 strip grades C67S and C75S are specified for springs, and ASTM A713 lists 1070 for wire.
  • Welding is not normally recommended at this carbon level; heating for welding needs preheat and stress relief and the heat-affected zone is brittle.
  • Matthey notes its C75E strip is less ductile than C60E strip, which shows the trend as carbon rises.

Heat treatment

  • Normalizing: about 900 °C (1650 °F) for C75E strip (Matthey), cooled in air.
  • Soft annealing: about 650–720 °C (1200–1330 °F) for C75E strip (Matthey).
  • Hardening: about 820–850 °C (1510–1560 °F) with an oil quench for 070A72 (Total Materia); 790–820 °C (1455–1510 °F) in water or oil for C75E strip (Matthey).
  • Tempering: depends on the hardness required; Matthey gives 350–700 °C (660–1290 °F) for C75E strip.
  • Spring stress relief after coiling: 385–399 °C (725–750 °F), held at least 1 hour, then air cooled (Total Materia, SAE 1070).

Typical uses

  • Flat springs, clutch plates and shims
  • Hardened and tempered blades, saw blades and doctor blades
  • Agricultural and masonry tools
  • Drawn spring wire and wire products

Carbon steels

Similar grades compared

GradeC %Mn %Cr %Ni %Tensile, first listed condition
1070 / 070A720.65–0.750.60–0.90≤0.40≤0.40700 MPa
1060 / C600.55–0.650.60–0.90≤0.40≤0.40680 MPa
1080 / 80C60.75–0.880.60–0.90≤0.30≤0.40700 MPa
1095 / C100S0.90–1.030.30–0.50≤0.40≤0.40830 MPa
1008≤0.100.30–0.50——303 MPa
1010 / C10E0.08–0.130.30–0.60≤0.30—320 MPa
1015 / C15E0.13–0.180.30–0.60≤0.30—340 MPa
10180.15–0.200.60–0.90≤0.20—400 MPa
1020 / C22E0.18–0.230.30–0.60≤0.30≤0.40380 MPa
1025 / C25E0.22–0.280.30–0.60≤0.30≤0.40400 MPa

Composition from the US standard where one exists, otherwise the first standard listed on each grade's page. Strength conditions differ between grades; open a grade for its full table.

Questions answered

Common questions

What is the equivalent of 1070 steel?

070A72 (old EN42) in the UK, 70C6 in India and S70C or SWRH72A in Japan are the usual equivalents. In Europe the nearest are the spring-strip grades C67S (1.1231) and C75S (1.1248). None is identical to 1070.

Is 1070 a spring steel?

Yes. Its 0.65–0.75 % carbon and hardenability suit springs, spring strip and spring wire, and ASTM A713 and EN 10132-4 list grades in this range. It is lower in cost than alloy spring steels but has lower hardenability.

What is the difference between 1070 and 1080?

1080 has more carbon (0.75–0.88 % against 0.65–0.75 %), so it hardens harder and is less ductile. Manganese is the same, 0.60–0.90 %. Both have low hardenability.

Is 1070 weldable?

Not readily. At 0.65–0.75 % carbon the heat-affected zone becomes hard and brittle. Welding needs preheat and post-weld heat treatment, and it is usually avoided.

What is the Japanese equivalent of 1070?

SWRH72A or SWRH72B wire rod (JIS G 3506, 0.69–0.76 % carbon) and S70C-CSP spring strip (JIS G 4802) are used. S70C in JIS G 4051 has the same limits as 1070 but only for plates, sheets and strips.

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1060 / C601060 is a high-carbon steel with about 0.60 % carbon, supplied hot rolled, annealed or normalized for parts that need a hard, wear-resistant surface or a spring-like temper.1080 / 80C61080 is a high-carbon steel with about 0.80 % carbon, used for spring strip, blades, tools and wear parts after hardening and tempering.1095 / C100S1095 is a high-carbon steel with about 0.95 % carbon, used for knives, blades, flat springs and hardened wear parts.AnnealingAnnealing heats steel to a set temperature, holds it and cools it slowly to make it softer, more ductile and easier to machine or cold form.Quenching and temperingQuenching and tempering hardens steel by cooling it rapidly from the austenite range to form martensite, then reheats it below Ac1 to trade some hardness for toughness.SAE / AISI numbersA four-digit SAE/AISI number such as 1045 or 4140 names a carbon or alloy steel by its chemistry: the first two digits identify the steel family and the last two give the nominal carbon content in hundredths of a percent.EN 10027 names and numbersEuropean steels carry two identifiers under EN 10027: a steel name (Part 1) such as S235JR, C45 or 42CrMo4 that describes the steel's use or chemistry, and a material number (Part 2) such as 1.0503 or 1.7225.BS 970 and the EN seriesBS 970 names steels with a six-character code such as 080M40, in which the first three digits give the steel type, the letter says how the steel is specified and the last two digits give the carbon content.IS 1570 and Indian designationsIndian steel names follow the letter-symbol code in IS 1762 (Part 1), which the IS 1570 schedules use: 45C8 means about 0.45% carbon, C for carbon steel and about 0.8% manganese, while alloy names such as 40Cr4Mo3 list each element with a multiplied content figure.JIS steel designationsJapanese JIS steel symbols start with S for steel and add letters for the steel family or its use, but the number means different things in different standards.

References

Sources

  1. SAE J403: Chemical Compositions of SAE Carbon Steels — Governs the US composition limits for 1060, 1070, 1080 and 1095.
  2. ICAST: SAE J403 / SAE J1397 UNS G10700, Hot Rolled — J1397 estimated minimum properties.
  3. Roymech: EN 10132 cold rolled narrow steel strip for heat treatment — EN 10132-4 spring-steel grades C60S to C100S: composition and strip properties.
  4. JIS G 4051: Carbon steels for machine structural use (Japanese Standards Association) — Limits for S58C, S60C, S65C, S70C and S75C checked against the 2016 edition; S60C to S75C apply only to plates, sheets and strips (Annex JB).
  5. IS 1570 (Part 2/Sec 1):1979 Schedules for wrought steels: carbon steels (public copy) — Table 1 carbon and manganese limits; Table 2 hot-rolled or normalized tensile limits.
  6. Total Materia: SAE 1070 — SAE J403:2014 composition and spring stress-relief treatment.
  7. Total Materia: B.S. 070 A 72 — Composition, heat treatment and cross-references; lists En42.
  8. Lamineries Matthey: Ck75 (C75E) strip datasheet — Heat treatment temperatures for C75E strip.
  9. Roymech: British Standard steel numbers — Links old EN numbers to BS 970 codes: 43D with 080A62, 42 with 070A72, 44 with 060A96.
  10. Total Materia: JIS S70C-CSP (JIS G 4802) — Carbon 0.65–0.75 %.
  11. Total Materia: JIS SWRH72A (JIS G 3506:2024) — Carbon, manganese and phosphorus limits.
  12. West Yorkshire Steel: CS70 spring steel — CS70 composition and related BS 1449 / BS 5770 names.
  13. BS 5770-2: steel strip for springs, cold rolled carbon and low alloy (withdrawn 2000) — Superseded British strip specification behind the CS70 to CS100 names.
  14. Nippon Steel: special steel sheet and strip catalogue (U006) — Mill check of S70C composition (strip grade).
  15. Tata Steel Thailand: high carbon wire rod grades (JIS G 3506) — SWRH62A/B, 72A/B and 82A/B carbon, silicon, manganese, phosphorus and sulphur.
  16. Rewon: BS 970 carbon steel grades with nearest SAE — Independent check of the BS 970 A-series carbon and manganese limits and the 080A62 / En43D pairing.

Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.