Method for performing full annealing heat treatment for alloy steel pipe

Abstract

The invention provides a method for performing full annealing heat treatment for an alloy steel pipe. A stepping continuous quenching and tempering furnace is used for sequentially performing first-order annealing treatment and second-order annealing treatment for the pipe to be treated, and comprises a quenching furnace and a tempering furnace which are sequentially arranged. The first-order annealing treatment includes the steps: feeding the quenching furnace and heating up a preheating section and a first heating section of the quenching furnace; keeping the temperature of a second heating section of the quenching furnace; and cooling a soaking section of the quenching furnace. The second-order annealing treatment includes the steps: discharging the quenching furnace, emptying a quenching device and rapidly feeding the tempering furnace; keeping the temperature of a preheating section and a front half of a first heating section of the tempering furnace and heating up the preheating section and the front half of a first heating section of the tempering furnace; keeping the temperature of a rear half of the first heating section and a second heating section of the tempering furnace; and cooling a soaking section of the tempering furnace, tapping and air cooling. The stepping continuous quenching and tempering furnace is used for performing full annealing heat treatment for the pipe, and technological requirements are met by a continuous efficient heat treatment mode.

Description

technical field [0001] The invention relates to the production field of alloy steel pipes, and more particularly, to a method for performing complete annealing and heat treatment on alloy steel pipes by adopting a step-by-step continuous quenching and tempering furnace. Background technique [0002] In order to ensure that the alloy steel pipe obtains a lower hardness index, a complete annealing heat treatment process is generally required. The traditional complete annealing heat treatment process is to heat the alloy steel pipe to a temperature of 30-50 °C above the austenite temperature and keep it for a period of time. After it is fully austenitized, it is cooled at a slow cooling rate (usually slow cooling with the furnace). After reaching 550 ℃, it is air-cooled to ensure that it meets the requirements of lower hardness indicators. The essence of the above heat treatment process is to provide a very slow cooling rate in the process of austenite to ferrite transformatio...

AI Technical Summary

Problems solved by technology

Generally, the complete annealing heat treatment process is used to produce such steel pipes and it is mainly carried out in chamber furnaces. Although the product quality requirements can be guaranteed, the production efficiency is low, the energy consumption is high, and it is only suitable for small batch production, especially for thin-walled pipes. limited, less efficient

[0007] When encountering the problem that the production batch of steel pipes that require a complete annealing process is large, but due to the limitation of the processing capacity of the chamber furnace, it is impossible to achieve continuous production in large quantities, and even seriously affect the production cycle and delivery time of the product, how to use the existing steps? The high-efficiency and energy-saving production advantages of the advanced quenching and tempering furnace can realize the efficient and continuous complete annealing heat treatment of 1Cr5Mo, 1Cr9Mo and other alloy steel seamless steel pipes, which is of great significance for giving full play to the advantages of scale and reducing production costs

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