New technique for producing high alloy steel high-end pipe by adopting cross rolling elongation technology

Abstract

The invention relates to a new technique for producing a high alloy steel high-end seamless pipe by adopting cross rolling elongation technology without perforation, comprising: molten high alloy steel which is externally refined is made into a hollow shell by centrifugal casting; the outside surfaces of the front and the rear ends of the hollow shell are respectively processed to be a 'gripping head' and a 'tail end head' with conicity, and machining and quality inspection are carried out on the inside and the outside surfaces as well as the 'gripping head' and the 'tail end head' of the hollow shell; heating is carried out; a mandril is inserted into the heated hollow shell, and then the hollow shell is sent into a cross rolling elongating mill for cross rolling, so that the pipe fittings having the wall thickness, the diameter and the length being in accordance with the requirements can be produced; the mandril is removed, and the head and the tail are cut off; finally, the qualified finished pipes can be obtained after sizing, heat treatment for finished product and finishing operation. The technique has short process flow and does not need cross rolling perforation, thus reducing the cost and improving the quality; due to small tapered treatment for the front and the rear ends, 'tail triangle' is avoided when the medium-thick walled pipes are produced, and the performance of secondary gripping is improved, thus improving the quality of the product and the production efficiency.

Description

Technical field: [0001] The invention relates to the manufacturing technology of seamless steel pipes, in particular to the manufacturing technology of high-end seamless steel pipes with large diameter, medium-thick wall and high alloy steel. Background technique: [0002] Steel has good comprehensive performance, can bear the required load and have the required service life cycle under different working conditions, and has good process performance. It is an indispensable and important basic material for national economic construction. Generally speaking, carbon-iron alloys with a carbon content of 0.02%-2% are called steel, and carbon-iron alloys with a carbon content greater than 2% are called cast iron. According to different classification standards, steel can be divided into different categories. According to the chemical composition of steel, it can be divided into carbon steel and alloy steel: [0003] In addition to iron and carbon, the components in carbon steel a...

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Problems solved by technology

[0008] It is not difficult to see that since cross-rolling perforation is also an indispensable technical link in the existing steel pipe cross-rolling production process, this process is used to produce high-end pipes, especially high-alloy steel pipes with poor plasticity, narrow deformable temperature range, and high deformation resistance. When making steel pipes, perforation defects and excessive temperature drop will cause various technical troubles, thus limiting the popularization and application of the above-mentioned processes in the production of high-end high-end steel pipes.

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