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Deformation by a principle known thermal processing, when thermal processing, high temperature produced compression deformation due to the heating temperature is uneven, the parts of the contract is also by other parts of the (low-temperature cooling zone or the first part) blocking when cooling, resulting in a variety of residual stresses and distortion. The steel market after thermal processing of steel is mainly for bending deformation.

Pipe diameter is small, relatively thick wall, you can take mechanical correction method (such as the use rolling machine, jack and the corresponding fixture) its correction. method is simple and easy. But pipe diameter, relatively thin wall, the inappropriate use of mechanical correction method, because it not only requires huge machinery and equipment and complex fixture, and likely to cause pipe local depression. The use of flame straightening method, although some operational difficulties, but the method is simple and works well.

Cold deformation of its melting temperature range is 0.25 times the absolute temperature. Since melting occurs when the temperature is lower than 0.25T recover small, hardened plastic deformation process in the leading role, which cold deformation of the metal is exposed resistance index as the increase in the degree of deformation continues to rise. Plasticity index, along with the degree of deformation increases gradually decreased, showed significant hardening, when the excessive accumulation of cold deformation of the metal to achieve the desired shape and size before the result of the plastic deformation of the "exhausted" arising from breaking. Therefore, the material of the cold deformation work is generally to be several times, only the nature of the material and the specific process conditions of total deformation of a certain value, and each time the cold deformation of the middle, to be hardened, can not continue billet deformation annealing to restore ductility. The advantage of cold deformation resulting product surface is smooth, precise size, shape regular. Appropriate choice of cold deformation - annealing cycle, we can draw an arbitrary hardness products. It is difficult to achieve thermal deformation.