Spring Steel

The desired properties of the steel to be used as a spring material can be described as sufficient load-bearing capacity, good elasticity, and unlimited resistance to fracture. These properties can only be achieved by selecting the appropriate steel and applying the correct heat treatment. It is crucial that the increase in the material’s strength does not lead to a loss of toughness.

An important aspect of manufacturing elastic components is that welding the parts can be problematic. Additionally, phenomena such as surface cracking effects, internal cracks resulting from heat treatment, and decarburization, which affects the homogeneous hardness of the material, can increase the risk of fracture. Furthermore, surface roughness, thermochemical hardening treatments (e.g., nitriding), and processes such as shot peening help reduce the risk of fracture.

When the steel material is shaped at room temperature, high bending stresses occur, which reduce the flexibility of the produced part. Therefore, it is advisable to relax the formed parts at lower temperatures.

Spring Steels and Their Alloys
Material Number	DIN	SAE / AISI	C	Si	Mn	Pmax	Smax	Cr	Mo	Nmax
1.0900	38 Si 6	-	0.35-0.42	1.40-1.60	0.50-0.80	0.050	0.050	-	-	0.007
1.0902	46 Si 7	-	0.42-0.50	1.50-1.80	0.50-0.80	0.050	0.050	-	-	0.007
1.0903	51 Si 7	-	0.47-0.55	1.50-1.80	0.50-0.80	0.045	0.045	-	-	0.007
1.0904	55 Si 7	9255	0.52-0.60	1.50-1.80	0.70-1.00	0.045	0.045	-	-	-
1.0906	65 Si 7	-	0.60-0.68	1.50-1.80	0.70-1.00	0.050	0.050	-	-	0.007
1.0908	60 SiMn 5	-	0.55-0.65	1.00-1.30	0.90-1.10	0.050	0.050	-	-	0.007
1.0961	60 SiCr 7	9262	0.55-0.65	1.50-1.80	0.70-1.00	0.045	0.045	0.20-0.40	-	0.007
1.0970	38 Si 7	-	0.35-0.42	0.15-035	0.50-0.80	0.045	0.045	-	-	0.007
1.1231	Ck 67	1070	0.65-0.72	0.15-0.35	0.60-0.90	0.035	0.035	-	-	-
1.1248	Ck 75	1075	0.70-0.80	0.15-0.35	0.60-0.80	0.035	0.035	-	-	-
1.1269	Ck 85	1086	0.80-0.90	1.50-1.80	0.45-0.65	0.035	0.035	-	-	-
1.1274	Ck 101	1095	0.95-1.05	0.15-0.35	0.40-0.60	0.035	0.035	-	-	-
1.5028	65 Si 7	-	0.60-0.70	1.50-1.80	0.70-1.00	0.035	0.035	-	-	-
1.5029	71 Si 7	-	0.68-0.75	1.50-1.80	0.60-0.80	0.035	0.035	-	-	-
1.5225	51 MnV 7	-	0.48-0.55	0.15-0.35	1.60-1.90	0.035	0.035	-	-	-
1.7103	67 SiCr 5	-	0.62-0.72	1.20-1.40	0.40-0.60	0.035	0.035	0.40-0.60	-	-
1.7138	52 MnCrB 3	50B50	0.48-0.55	0.15-0.35	0.75-1.00	0.035	0.035	0.40-0.60		B 0.0005
1.7176	55 Cr 3	5155	0.52-0.59	0.15-0.40	0.70-1.00	0.035	0.035	0.60-0.90	-	-
1.7701	51 CrMoV 7	-	0.48-0.56	0.15-0.40	0.70-1.00	0.035	0.035	0.90-1.20	0.15-0.25	-
1.8159	50 CrV 4	6150	0.47-0.55	0.00-0.40	0.70-1.00	0.035	0.035	0.90-1.20	-	-
1.8161	58 CrV 4	-	0.55-0.62	0.15-0.40	0.70-1.00	0.035	0.035	0.90-1.20	-	-

Mechanical Properties of Spring Steels
Material Number	DIN	SAE / AISI	Yield Strength	Tensile Strength	Elongation at Break
Material Number	DIN	SAE / AISI	( N/mm2 )	( N/mm2 )	( % )
1.0900	38 Si 6	-	1030	1180-1370	6
1.0902	46 Si 7	-	1080	1275-1470	6
1.0903	51 Si 7	-	1130	1320-1570	6
1.0904	55 Si 7	9255	1080	1275-1470	6
1.0906	65 Si 7	-	1080	1275-1470	6
1.0908	60 SiMn 5	-	1030	1320-1520	6
1.0961	60 SiCr 7	9262	1130	1320-1570	6
1.0970	38 Si 7	-	1030	1180-1370	6
1.7103	67 SiCr 5	-	1320	1470-1670	6
1.7176	55 Cr 3	5155	1180	1370-1620	6
1.7701	51 CrMoV 7	-	1180	1370-1670	6
1.8159	50 CrV 4	6150	1180	1370-1620	6
1.8161	58 CrV 4	-	1320	1470-1670	6

Heat Treatment of Spring Steels
Material Number	DIN	SAE / AISI	Forging Temperature (°C)	Warm Forming Temperature (°C)	Normalizing Temperature (°C)	Annealing Temperature (°C)	Quenching			Tempering Temperature
							(°C )	 Water 	Oil
							(°C )	 Water 	Oil
1.0900	38 Si 6	-	1050-850	900-800	850-880	640-680	830-860	*	-	350-550
1.0902	46 Si 7	-	1100-850	900-830	850-880	640-680	830-860	*	-	430-500
1.0903	51 Si 7	-	1050-850	900-820	850-880	640-680	830-860	*	-	350-550
1.0904	55 Si 7	9255	1050-850	900-830	850-880	640-680	830-860	+	*	430-500
1.0906	65 Si 7	-	1050-851	900-830	850-880	640-680	830-860	-	*	430-500
1.0908	60 SiMn 5	-	1100-851	900-830	850-880	640-680	830-860	-	*	400-550
1.0961	60 SiCr 7	9262	1050-850	900-830	850-880	640-680	830-860	-	*	350-550
1.0970	38 Si 7	-	1050-850	900-830	850-880	640-680	830-860	*	-	350-550
1.1231	Ck 67	1070	-	-	-	650-690	815-845	-	*	300-500
1.1248	Ck 75	1075	-	-	-	650-690	810-840	-	*	300-500
1.1269	Ck 85	1086	-	-	-	650-690	800-830	-	*	300-500
1.1274	Ck 101	1095	1050-850	880-800	800-830	640-680	830-860	-	*	430-500
1.5028	65 Si 7	-	1050-853	900-830	830-860	640-680	830-860	-	*	470-540
1.5029	71 Si 7	-	1100-853	900-820	850-880	640-680	830-860	-	*	430-500
1.5225	51 MnV 7	-	1050-850	880-800	830-860	640-680	830-860	-	*	430-500
1.7103	67 SiCr 5	-	1050-850	900-820	850-880	640-680	830-860	-	*	430-500
1.7138	52 MnCrB 3	50B50	1050-854	900-800	850-880	640-680	830-860	-	*	350-550
1.7176	55 Cr 3	5155	1100-854	900-800	850-880	640-680	830-860	-	*	350-550
1.7701	51 CrMoV 7	-	1050-850	920-830	850-880	640-680	830-860	-	*	350-550
1.8159	50 CrV 4	6150	1050-850	920-820	850-880	640-680	830-860	-	*	350-550
1.8161	58 CrV 4	-	1050-855	920-830	850-880	640-680	830-860	-	*	350-550

Applications of Spring Steel
Material Number	DIN	SAE / AISI	Areas of Use
1.0900	38 Si 6	-	For rail vehicles: Leaf springs, large tension and compression springs, plate springs, disc springs, spring washers.
1.0902	46 Si 7	-	In general mechanical engineering, especially leaf springs, helical springs, disc springs, and spiral springs, for vehicles and airplanes.
1.0903	51 Si 7	-	In general mechanical engineering, particularly leaf springs, helical springs, disc springs, and spiral springs, for vehicles and airplanes.
1.0904	55 Si 7	9255	Leaf springs, plate springs, and disc springs thicker than 7 mm.
1.0906	65 Si 7	-	Leaf springs for vehicles thicker than 7 mm, helical springs and helical springs with medium and high preloading.
1.0908	60 SiMn 5	-	Leaf springs for vehicles thicker than 7 mm, with medium and high preloading, disc springs, helical springs, and spring washers.
1.0961	60 SiCr 7	9262	For vehicles: Leaf springs thicker than 7 mm, also helical and disc springs in general mechanical engineering.
1.0970	38 Si 7	-	Spring washers and safety washers for screws, tension springs for superstructure applications.
1.1231	Ck 67	1070	Cold-rolled steel strips for springs with high precision and surface quality.
1.1248	Ck 75	1075	Cold-rolled steel strips for springs with high precision and surface quality.
1.1269	Ck 85	1086	Cold-rolled steel strips for springs with high precision and surface quality.
1.1274	Ck 101	1095	For overloaded tension springs, cold-rolled strip steel for springs, especially in the watchmaking industry.
1.5028	66 Si 7	-	For vehicles up to 25 mm thick: Leaf springs, helical springs, and torsion bars.
1.5029	71 Si 7	-	For the watch industry and similar applications, heavily loaded tension springs.
1.5225	51 MnV 7	-	For high loads: Leaf springs, helical springs, and conical springs.
1.7103	67 SiCr 5	-	Particularly heavily loaded helical springs, torsion bars with diameters of 25 to 40 mm, valve springs, disc springs, and spring washers.
1.7138	52 MnCrB 3	50B50	Leaf springs for vehicles under high load.
1.7176	55 Cr 3	5155	For vehicles: Leaf springs, torsion bars, and helical springs, especially large tension and compression springs.
1.7701	51 CrMoV 7	-	For vehicles: Overloaded tension, helical, compression springs, and torsion bars.
1.8159	50 CrV 4	6150	For overloaded vehicle leaf springs.
1.8161	58 CrV 4	-	Highly overloaded, large-sized spiral springs, helical springs, disc springs, and spring washers.