General Information

The spring is required to change its shape elastically under any load and re-gain its previous shape when the load is removed. At that point, the elasticity of the material used for producing the spring becomes important. The spring steels are the steel materials for producing a variety of springs. The steel materials for spring production vary depending on the operational conditions. The operational conditions of the springs may be in form of loading, pulling, pressing and torsional.

The typical examples for the springs according to the loading types can be listed as follows: Leaf springs forced by torsion, bendable springs; helical springs loaded by pulling or pressing, spring washers for loading by torque, stabilizer springs turned inside out.

CLASSIFICATION.
The spring steels are divided in to two classes according to their characteristics:

-Quality steels, and
-Noble steels

TYPES
The spring steels made of quality steels are divided in to 3 types based on their alloy elements:

- Silicate (38 Si 7,46 Si7, 5lSi 7, 55 Si 7, 65 Si 7)
- Silicate-Chromium (60 Si Cr 7)
- Silicate-Manganese (60 Si Mn 5)

The spring steels made of noble steels are divided in to 5 types based on their alloy elements
- Silicate (66 Si 7)
- Chromium (55 Cr 3)
- Silicate -Vanadium (50 Cr V 4 and 58 Cr V 4)
- Chromium-Molybdenum-Vanadium (51 Cr Mo V 4)

On the other hand, some of the properties are classified as cold for the thin cross sections especially and hot for the thick cross sections.

The C percentage of the cold springs is generally high, with high surface smoothness and cold processed.

The hot wound springs have larger cross sections and have hardening characteristics absolutely .

Stainless steels

DESCRIPTION

The term Stainless Steel is used for the materials that are resistant to the atmospheric effects, corrosive materials and high temperatures, containing essentially iron, chromium, nickel and carbon. When alone, the iron contained in the stainless steel by about 75%, is not resistant to the external effects, but when alloyed with chromium and or chromium-nickel at various proportions, it gains the property of not rusting
The chromium incorporated in the steel forms an oxide layer on the surface of the steel when it comes in contact with the air. The protection of this rust-proofing layer increases with the luster of the surface.

CLASSIFICATION

The stainless steels are grouped under three main categories according to their structure:
- Ferritic
- Austenitic, and
- Martensitic steels.

Ferritic steels:
This type of steels are essentially iron and chromium alloys,
The anti-magnetic austenitic group in included in the AISI standard as Group 300. A material with suitable properties for almost any application may be selected out that group containing a large variety of types. The types with wide applications areas are 304 309, 310 and 316

Martensitic steels:
The steels of this type essentially contain chromium not less than 11.5%. High carbon content (15-20%) in the structure is the most prominent characteristic of the group. Based on the foregoing, they can be hardened by tempering as opposed to the previous two groups.

The Martensitic steels are magnetic and are used mostly in the places open to corrosion and requiring tempering resistance in particular (pump shafts, valves etc.). The widest used varieties are 410 and 420.