SU1196048A1 - Method of producing cold-deformed thick-walled tubes from austenite stainless steel - Google Patents

Abstract

METHOD OF MAKING AREA and the ratio of the fractional deformation of 15-30. Sh

Description

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00 1 The invention relates to the processing of metals by pressure and can be used in the manufacture of boiler tubes. The purpose of the invention is to reduce the grain size of the metal pipe and increase its heat resistance. CjnuHocTb of the method lies in the fact that hot billets of austenitic stainless steels are subjected to single-pass periodic cold rolling with two pairs of rolls 48 with a reduction of 60% or more and a fractional strain factor of 15-30. The method was tested when rolling tubes of steel 12X18H12T on HPT90 mills with one and two pairs of rolls along the routes 93X14-9-50x8 mm with variation of deformations from 55 to 70% and fractional deformation within 13-40. To each of the options rolling from 5 to 10 pcs. The results of the experiments are given in table.1 and 2. Table 1

Note. When fractional deformation of less than 13 is the destruction of the pipe.

Note. Time to destruction 3-6 thousand hours.

As follows from the above results, when rolling according to a known method on a HPT mill with one pair of rolls, the grain size in all cases x reaches 6-8 points, the long-term ductility (elongation -8 10-17% with durability 3-6 thousand h .

When rolling tubes according to the proposed method, on a CPT mill with two pairs of rolls with a reduction of 60-70, the grain size decreases to 4-6 points, and when the deformation is fractional in the range of 15-30, the graininess does not exceed 4 points. The pipes manufactured by this method have an increased long-term ductility of about 28-35% with the same test duration as pipes manufactured by a known method.

Investigations of the non-uniformity of money formations across the wall thickness

It is believed that when rolling pipes according to the proposed method it is minimal. This is due to the considerable back pressure between the pairs of rolls, leading to the equalization of the flow rates of the metal layers along the wall thickness.

Under the proposed method, a batch of extremely thick-walled boiler tubes of steel 12X18H12T measuring 42x11.0 mm in an amount of 50 tons was manufactured under industrial conditions. The pipes were rolled on an HPT90 mill with two pairs of rolls along the route

93x14.042x11.0 mm with n 20.

The grain size of the finished pipes is within 3-7 points. Durable plasticity 5 is in the range of 27-35%. The code of suitable uniformity is increased to 100%.

Thus, the proposed method in comparison with the known permissible 511960486

The proposed method makes it possible to reduce the long-term plasticity of the metal to increase the yield of the suitable one (reducing the pipe with the same long-term strength, by applying Srak) by 40% differently grain size. increase their heat resistance. tosti and heat resistance.

Claims (1)

METHOD FOR PRODUCING COLD DEFORMED SPECIFIC WALL PIPES FROM AUSTENITIC STAINLESS STEELS, which includes single-pass periodic cold rolling of hot-rolled billets, characterized in that, in order to reduce the different grain size of the pipe metal and increase the heat resistance of more than 60%, deformations 15-30. 1196048 ² with a compression of 60% or more and a crushing coefficient of deformation of 15-30. The method was tested during rolling of 12Kh18N12T steel pipes at KhPT90 mills with one and two pairs of rolls along the routes 93X14-9-50x8 mm with varying strains from 55 to 70% and fractional strain within 13-40. For each of the options rolling from 5 to 10 pcs. The experimental results are shown in tables 1 and 2.