Oil hardened & tempered steel wire

Summary:
Oil hardened and tempered spring steel wire, also as called wire for quenched and tempered spring, is sort of high carbon steel wire especially used for making springs in automobile industry.

Brief Introduction:
China oil hardened & tempered steel wire was mainly for high carbon wire and certain 50CrV wire approximately 30 years before. After that, as automobile industry rapidly developed with wire advances in technology, 55CrSi, 67CrV and such wire rod materials gradually occupied more shares in market. At the very beginning, China imported oil hardened & tempered steel wire rods from Japan but later on China domestic steel plants started to manufacture and continuously improve the quality to meet enormous demands from world till today.

Oil hardened and tempered spring steel wire with carbon content of 0.50%-0.80% in percentage from grade to grade is widely used for making springs in automobile industry that require extremely perfect anti-fatigue features, excellent thermo-stability, strong toughness, and also resistance against permanent set. Oil hardened and tempered spring steel wire is specially for making the valve springs of engine, clutch springs, and suspension springs that are regarded as crucial security units of motor. For the wire surface, there is definitely requirement that any harmful defects such as scratch, crack, corrosion, fold, knot, scab and sunken are not allowed by standard. For final purpose, oil hardened and tempered steel wire is divided into three grades by tensile strength & anti-fatigue features, one for general use as grade FD, the other for spring use in automobile as grade TD, and the last for valve spring use as grade VD. Further, the strength tensile tolerance for FD should be 70mpa maximum, for TD 60mpa maximum and for VD 50mpa maximum. Wrapping test should be required for those wires with diameter 3.0mm maximum and torsion test for those wires with diameter 0.70mm-6.00mm and then bending test for those wires with diameter 6.00mm minimum. For any test items beyond manufacturing standard, customer is needed to give the specific requirement in the contract. Delivery packing state of the oil hardened and tempered spring steel wire should be in coil or spool.

Chemical Compostion (%)
Grade	C	Si	Mn	P	S	Cr	V	Ni	Cu
FDC	0.60-0.75	0.17-0.37	0.90-1.20	≤ 0.030	≤ 0.030	≤ 0.25	—	≤ 0.35	≤ 0.25
TDC
VDC
FDCrV	0.46-0.54	0.17-0.37	0.50-0.80	≤ 0.025	≤ 0.020	0.80-1.10	0.10-0.20	≤ 0.35	≤ 0.25
TDCrV
VDCrV
FDSiMn	0.56-0.64	1.50-2.00	0.70-1.00	≤ 0.025	≤ 0.020	—	—	≤ 0.35	≤ 0.25
TDSiMn
FDSiCr	0.51-0.59	1.20-1.60	0.50-0.80	≤ 0.025	≤ 0.020	0.50-0.80	—	≤ 0.35	≤ 0.25
TDSiCr
VDSiCr
VDSiCrV	0.62-0.70	1.20-1.60	0.50-0.80	≤ 0.025	≤ 0.020	0.50-0.80	0.10-0.20	≤ 0.035	≤ 0.12
Cu content should be 0.12% maximum in percentage for grade TD and VD

Wire for quenched and tempered spring
Apply for mechanical & motor industry use
Standard: GB/T18983-2017; ISO8458-3:2002

1. Classify, code and diameter

CLASSIFICATION		STATIC LEVEL (GENERAL)	FATIGUE LEVEL (M)	FATIGUE LEVEL (H)
TENSILE STRENGTH	STRENGTH (L)	FDC	TDC	VDC
	STRENGTH (M)	FDCrV, FDSiMn	TDSiMn	VDCrV
	STRENGTH (H)	FDSiCr	TDSiCr-A	VDSiCr
	STRENGTH (S)	—	TDSiCr-B, TDSiCr-C	VDSiCrV
DIAMETER (MM)		0.50 -18.00	0.50 -18.00	0.50 -10.00

(1) Wire on static level for general use marked with “FD”.
(2) Wire on fatigue level (M) for spring use made into clutch and suspension marked with “TD”.
(3) Wire on fatigue level (H) for frequent & drastic activity such as valve spring marked with “VD”.
Wire diameter of TDSiCr-B and TDSiCr-C should be 8.0-18.0mm

2. Wire on static level and fatigue level (M)

DIA(MM)	T/S (MPA)						SECTION SHRINKAGE (Z: %) MIN
	FDC TDC	FDCrV - A TDCrV - A	FDSiMn TDSiMn	FDSiCr TDSiCr - A	TDSiCr - B	TDSiCr - C	FD	TD
0.50 - 0.80	1800-2100	1800-2100	1850-2100	2000-2250	—	—	—	—
＞ 0.80 - 1.00	1800-2060	1780-2080	1850-2100	2000-2250	—	—	—	—
＞1.00 - 1.30	1800-2010	1750-2010	1850-2100	2000-2250	—	—	45	45
＞1.30 - 1.40	1750-1950	1750-1990	1850-2100	2000-2250	—	—	45	45
＞1.40 - 1.60	1740-1890	1710-1950	1850-2100	2000-2250	—	—	45	45
＞1.60 - 2.00	1720-1890	1710-1890	1820-2000	2000-2250	—	—	45	45
＞2.00 - 2.50	1670-1820	1670-1830	1800-1950	1970-2140	—	—	45	45
＞2.50 - 2.70	1640-1790	1660-1820	1780-1930	1950-2120	—	—	45	45
＞2.70 - 3.00	1620-1770	1630-1780	1760-1910	1930-2100	—	—	45	45
＞3.00 - 3.20	1600-1750	1610-1760	1740-1890	1910-2080	—	—	40	45
＞3.20 - 3.50	1580-1730	1600-1750	1720-1870	1900-2060	—	—	40	45
＞3.50 - 4.00	1550-1700	1560-1710	1710-1860	1870-2030	—	—	40	45
＞4.00 - 4.20	1540-1690	1540-1690	1700-1850	1860-2020	—	—	40	45
＞4.20 - 4.50	1520-1670	1520-1670	1690-1840	1850-2000	—	—	40	45
＞4.50 - 4.70	1510-1660	1510-1660	1680-1830	1840-1990	—	—	40	45
＞4.70 - 5.00	1500-1650	1500-1650	1670-1820	1830-1980	—	—	40	45
＞5.00 - 5.60	1470-1620	1460-1610	1660-1810	1800-1950	—	—	35	40
＞5.60 - 6.00	1460-1610	1440-1590	1650-1800	1780-1930	—	—	35	40
＞6.00 - 6.50	1440-1590	1420-1570	1640-1790	1760-1910	—	—	35	40
＞6.50 - 7.00	1430-1580	1400-1550	1630-1780	1740-1890	—	—	35	40
＞7.00 - 8.00	1400-1550	1380-1530	1620-1770	1710-1860	—	—	35	40
＞8.00 - 9.00	1380-1530	1370-1520	1610-1760	1700-1850	1750-1850	1850-1950	30	35
＞9.00 - 10.00	1360-1510	1350-1500	1600-1750	1660-1810	1750-1850	1850-1950	30	35
＞10.00 - 12.00	1320-1470	1320-1470	1580-1730	1660-1810	1750-1850	1850-1950	30	35
＞12.00 - 14.00	1280-1430	1300-1450	1560-1710	1620-1770	1750-1850	1850-1950	30	35
＞14.00 - 15.00	1270-1420	1290-1440	1550-1700	1620-1770	1750-1850	1850-1950	30	35
＞15.00 - 17.00	1250-1400	1270-1420	1540-1690	1580-1730	1750-1850	1850-1950	30	35

For FDSiMn & TDSiMn, as wire diameter≤5.00mm, Section shrinkage(Z) Should be 35% minimum; As diameter 5.00-14.00MM, section shrinkage(Z) should be 30% minimum

3. Wire on fatigue level (H)

DIA(MM)	T/S (MPA)				SECTION SHRINKAGE (Z: %) MIN
	VDC	VDCrV - A	VDSiCr	VDSiCrV
0.50 - 0.80	1700-2000	1750-1950	2080-2230	2230-2380	—
＞ 0.80 - 1.00	1700-1950	1730-1930	2080-2230	2230-2380	—
＞1.00 - 1.30	1700-1900	1700-1900	2080-2230	2230-2380	45
＞1.30 - 1.40	1700-1850	1680-1860	2080-2230	2210-2360	45
＞1.40 - 1.60	1670-1820	1660-1860	2050-2180	2210-2360	45
＞1.60 - 2.00	1650-1800	1640-1800	2010-2110	2160-2310	45
＞2.00 - 2.50	1630-1780	1620-1770	1960-2060	2100-2250	45
＞2.50 - 2.70	1610-1760	1610-1760	1940-2040	2060-2210	45
＞2.70 - 3.00	1590-1740	1600-1750	1930-2030	2060-2210	45
＞3.00 - 3.20	1570-1720	1580-1730	1920-2020	2060-2210	45
＞3.20 - 3.50	1550-1700	1560-1710	1910-2010	2010-2160	45
＞3.50 - 4.00	1530-1680	1540-1690	1890-1990	2010-2160	45
＞4.00 - 4.20	1510-1660	1520-1670	1860-1960	1960-2110	45
＞4.20 - 4.50	1510-1660	1520-1670	1860-1960	1960-2110	45
＞4.50 - 4.70	1490-1640	1500-1650	1830-1930	1960-2110	45
＞4.70 - 5.00	1490-1640	1500-1650	1830-1930	1960-2110	45
＞5.00 - 5.60	1470-1620	1480-1630	1800-1900	1910-2060	40
＞5.60 - 6.00	1450-1600	1470-1620	1790-1890	1910-2060	40
＞6.00 - 6.50	1420-1570	1440-1590	1760-1860	1910-2060	40
＞6.50 - 7.00	1400-1550	1420-1570	1740-1840	1860-2010	40
＞7.00 - 8.00	1370-1520	1410-1560	1710-1810	1860-2010	40
＞8.00 - 9.00	1350-1500	1390-1540	1690-1790	1810-1960	35
＞9.00 - 10.00	1340-1490	1370-1520	1670-1770	1810-1960	35