Materials

Carbon spring steels

Carbon spring steels contain a carbon percentage between 0.60% and 0.90% and are widely used in the production of springs and high-strength wires.

HEAT TREATMENT OF STEELS C60, C75 and 51CrV4

After blanking operation, carbon steel parts undergo the delicate process of heat treatment in order to achieve the best grade of hardness and elasticity, depending on their function.

Heat treatment can be done in accordance with two different processes:

a) Oil quenching and tempering

Quenching consists in heating the parts at an austenitizing temperature and then cooling them in oil to room temperature. The so obtained martensitic structure features high hardness and brittleness. Tempering consists in reheating the parts, until they achieve the best grade of hardness and toughness. Parts are finally cooled to room temperature.

b) Austempering in Salt bath

Austempering consists in heating parts at an austenitizing temperature and then rapidly cooling them in salt bath to a certain temperature, which is maintained until their structure convert into lower bainite. The so obtained bainitic structure features high tensile strength, hardness and excellent toughness. Parts are then cooled to room temperature. Austempering process can reduce the possibility of material deformations.

Notes:

C60 Material: BENERI retaining rings of small dimensions are made of Steel C60, instead of Steels C67 or C75 as defined in the standards. Steel C60 has a lower percentage of carbon and is therefore more elastic, thus reducing the risk of brittleness defects, which may occur after some galvanic coatings

Decarburization: a full decarburization is not accepted; a maximum 0,05 mm thickness of partial decarburization is accepted by several users of retaining rings.

Hardness: Standard unit of Hardness is HRC. Vickers scale is used when thickness is < 1 mm.

Maximum / lowest usage temperature**:

the performance of a retaining ring is not limited to a specific point of temperature. We can estimate a maximum usage temperature of 125° C. Low temperatures should be avoided as they may cause embrittlement. The application of the ring shall be always considered.

** Consult BENERI® experts for the use at high / low temperatures
 

Hard drawn carbon steel

Hard drawn carbon steel is a highly magnetic material, widely used in the production of snap rings.

Hard drawn carbon steel comes already tempered. After blanking operations, the parts undergo a heat treatment for stress relief at high-temperature in order to reach the best grade of elasticity.

Martensitic stainless steel

Martensitic stainless steel is an alloy of chromium and carbon, which acquires a martensitic structure with cubic-centered body (bcc) after heat treatment. It is a ferromagnetic material; it can be heat-treated and is corrosion-resistant, limited to mild environments.

HEAT TREATMENT OF MARTENSITIC STAINLESS STEEL

After blanking operations, martensitic stainless steel parts undergo the delicate process of heat treatment, in order to achieve the best grade of hardness and elasticity.

Heat treatment for Stainless steel X39 consists in quenching and tempering.

Quenching consists in heating the parts to an austenitizing temperature and then cooling them in a protected atmosphere, thus obtaining a final structure called martensite.

Tempering consists in reheating the parts, until they achieve the best grade of toughness and ductility.

The high temperature of this stage promotes the precipitation of carbides and the depletion of chromium, thus reducing the corrosion resistance properties of the material.

Parts in martensitic stainless steel X39 are therefore subject to brittleness and absorption of brittle elements in some specific environments (such as marine), with consequent limited corrosion resistance and lower performance in flexion test (≈10 ° - 15 °).

We suggest Austenitic stainless steels, when excellent corrosion resistance is required.

Notes:

Maximum / lowest usage temperature**: the performance of a retaining ring is not limited to a specific point of temperature. We can estimate a maximum usage temperature of 300 ° C. Low temperatures should be avoided as they may cause embrittlement. The application of the ring shall be always considered.

** Consult BENERI® experts for the use at high / low temperatures

Austenitic stainless steel

Several laboratory tests we conducted on different types of stainless steels (X39, PH15/7Mo and PH 17/7) have proven Austenitic stainless steels - Series 300 to be the best material with respect of mechanical properties and corrosion resistance.

Austenitic stainless steels have a cubic-face-centered structure (cfc), they are amagnetic in the annealed state and can be hardened only by cold working.

They have and excellent resistance to low temperatures and good resistance to high temperatures.

Austenitic stainless steels is not subject to quenching, so final hardness of the parts depends on material hardness.

For a correct and easier assembly of retaining rings made in austenitic stainless steel we strongly recommend the use of the proper pliers, provided with stop and return screw.

Notes about corrosion resistance and magnetism of each type of austenitic stainless steels:

• AISI 301: its resistance to corrosion depends on environment, temperature and duration of usage. It is resistant in urban environment, soft water, food and many components used in chemical, textile and oil industries. It is not resistant to corrosion in chloride environment. It is not magnetic but becomes ferromagnetic in proportion to cold drawn percentage.

• AISI 304: It is corrosion resistant in several environments and in contact with components used in chemical, textile and food industries. It is nonmagnetic when solubilized.

• AISI 316 L: it has an excellent resistance to localized corrosion in exposed atmosphere and in several types of salts, organic acids and food components; it has a moderate resistance to corrosion in reduced acid solutions. It is sensitive to intercrystalline corrosion and is non-magnetic (it may present a slight magnetism due to cold working)

Notes:

Maximum / lowest usage temperature**: the performance of a retaining ring is not limited to a specific point of temperature. The application of the ring shall be always considered.

** Consult BENERI® experts for the use at high / low temperatures