WHY CYLINDER BARREL NEED STRESS RELEASED AFTER COLD DRAWING

 Stress released is a technique method usually for cold drawn seamless tube and honed cylinder barrel production process. With focus on the Hydraulic Cylinder Industry the following components are made by a Cold Drawing process:

When a 75,000 PSI minimum yield strength is specified for the design of parts in hydraulic and pneumatic cylinder there are several options for the material that will meet this regular specification.

  1. a) Cold Drawn Cylinder Tubes – both welded or seamless

Grades : E355 , AISI-1020 or AISI-1026

  1. b) Cold Drawn Round Bars used for producing Piston Rods

Grades : 1045 to ASTM-A311 or 38MnVS6

For both products is strongly recommend after the Cold Drawing a further annealing process by stress relieving.  The temperature and the time of permanence in the furnace depends on the steel grade of the product and also the cooling temperature and the time is extremely important to achieve the expected result.

Cold Drawing Tubes and Bars induce stresses in the product. These stresses can cause loss of tolerance, cracking and distortion, and contribute to in-service failures.

In the case of Cylinder Barrel Tubes, with the exception of tubes called RTU ready to use or S.S.I.D. that for tolerance reasons and internal roughness do not require heat treatment after the cold drawing operation, in all the other cases stress relieving is  necessary, and in some cases, mandatory.

A stress relief operation is typically used to remove internal (residual) stresses that have accumulated in the material. The stress relief process is performed by heating in a furnace to a temperature below the lower critical temperature (Ac1) and holding at that temperature long enough to achieve the desired reduction in residual stresses

In the case of chrome bars used for the production of piston rods in different steel grades such as: CK-45, C48, Cf53, 20MnV6, 38MnVS6, 42CrMo4 Q+T, etc.

The work cycle to produce a chrome bar may vary depending on the type of material from which you start.

Generally the size of up to 30mm diameter people are using cold drawn bars. The work cycle start with grinding, polishing and chrome plating.

Size greater than the diameter. 30 mm is preferred start from hot rolled steel bars. The working cycle starts with peeling, straightening, grinding, polishing and chrome plating.

Stress relief is a simple heat-treating operation for all Cold Drawn Steel Products that depends strongly on the proper selection of temperature and time at temperature for its success. A proper cooling rate is also a surprisingly important factor.

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