GARBA 177 Premium

Precipitation hardenable stainless spring wire. Shaved and EC-tested *)
For applications demanding high fatigue properties

GARBA 177 Premium is a semi-austenitic precipitation-hardenable stainless steel with high relaxation resistance at elevated temperatures and excellent fatigue properties. This material has good formability and good form stability during the precipitation hardening heat treatment and a moderate level of corrosion resistance. The shaved surface improves the fatigue resistance as compared to GARBA 177PH.

Chemical composition

C (%) Si (%) Mn (%) P max. (%) S max. (%) Cr (%) Ni (%) Al (%)
0.09 0.70 1.00 0.040 0.015 16.00 - 18.00 6.50 - 7.80 0.70 - 1.50

Mechanical properties

For round wire

Diameter (mm) Tolerance (± mm) Tensile Strength (N/mm²) Tensile strength after heat treatment 480C 1h (N/mm²)
0.30 - 0.40 0.005 1885 - 2165 2205 - 2525
0.41 - 0.50 0.008 1860 - 2130 2180 - 2490
0.51 - 0.65 0.008 1810 - 2070 2130 - 2430
0.66 - 0.80 0.010 1810 - 2060 2130 - 2430
0.81 - 1.00 0.010 1780 - 2030 2100 - 2390
1.01 - 1.25 0.015 1720 - 1960 2040 - 2310
1.26 - 1.50 0.015 1670 - 1910 1990 - 2260
1.51 - 1.75 0.015 1610 - 1850 1910 - 2180
1.76 - 2.00 0.015 1570 - 1800 1900 - 2160
2.01 - 2.50 0.015 1540 - 1770 1860 - 2120
2.51 - 3.00 0.020 1500 - 1710 1820 - 2060
3.01 - 3.50 0.020 1400 - 1600 1660 - 1940
3.51 - 4.25 0.020 1350 - 1550 1620 - 1920
4.26 - 5.00 0.025 1310 - 1500 1580 - 1800
5.01 - 5.60 0.025 1300 - 1490 1550 - 1790

Surface conditions

Surface performance
AC-surface 0.30–5.60 mm Ø. The AC-coating can be removed before heat treatment by using a 10-20% nitric acid pickle at room temperature.

Surface condition

Surface condition – non-destructive testing
In the standard size range 2.00-5,60 mm the wire can be tested continuously in Eddy Current equipment to a surface level of >40 microns.

Physical properties



E and G modulus of elasticity

Abt. 190 kN/mm2 in drawn condition.
Abt. 200 kN/mm2 after heat treatment.

E and G modulus of shear

Abt. 73 kN/mm2 in drawn condition.
Abt. 78 kN/mm2 after heat treatment.
Density: 7.90 kg/dm3.

Heat conductivity

Temperature oC 20 100 300
W/(m* oC) 15.0 15.5 19.0

Linear expansion

Pro oC 30-100 30-200 30-300
x10-6 13.0 13.5 14.0

Recommendations

Heat treatment

Normal procedure for precipitation hardening is heat treatment at 480oC (896oF) for 1 hour and then air cooling. This should be done as soon as possible after spring coiling. The tensile strength of the wire before and after this treatment is given in the table in previous page.

Shot peening

In order to obtain optimum fatigue properties, the process time should be adjusted to get a complete treatment. Size of shots should be adapted to wire dimension, pitch and shot peening equipment.
Shot peening of the inside of the spring coils is particularly critical.