Large diameter stainless steel tube annealing treatment process introduction
Posted by： Hangao Time：2024-2-24 16:02:16
I. Overview
Stainless steel pipe is a high-performance material widely used in petroleum, chemical, pharmaceutical, food, machinery, aviation and other fields, and its excellent corrosion resistance, mechanical properties and aesthetics make it widely favored. However, stainless steel pipe in the production process, due to cold working, welding and other reasons, will lead to internal stress, carbide precipitation, grain coarsening and other defects within the stainless steel pipe, thus reducing the corrosion resistance and plasticity of the stainless steel pipe, affecting the service life and quality of the stainless steel pipe. In order to eliminate these defects and improve the performance of steel pipe, it is usually necessary to annealing solution heat treatment of stainless steel pipe.
Solution treatment is a heat treatment process, the principle is to heat the steel pipe to a high temperature, so that the various phases in the steel pipe (such as ferrite, carbide, etc.) fully dissolved in austenite, and then rapidly cooled, so that the dissolved phase is too late to precipitate, retained in the austenite, the formation of a single-phase austenitic organization. In this way, the internal stress of the steel pipe can be eliminated, reduce the hardness, increase plasticity and toughness, improve corrosion resistance, so that the steel pipe has a uniform organization and performance.
II. Process flow
The process flow of annealing solution heat treatmentof large diameter stainless steel pipe is as follows: 1、Automatic loading device will deliver the pipe on the roller conveyor.
2、Pipe rotating transportation, uniform speed into the induction heating section and insulation section to annealing heat treatment.
3、Pipe enters 360℃ spraying device to cool evenly.
4、Pipe enters blanking table after cooling.
5、Trigger the automatic blacking device, automatically lifting the pipe to the discharging platform.
6、The whole process of steel pipe will not cause any scratch.
III. The principle of process The main process parameters of annealing treatment of large diameter stainless steel pipe include annealing solution temperature, insulation time, cooling speed, the selection of these parameters has an important impact on the organization and properties of the steel pipe, should be based on the material of the steel pipe, specifications, uses and other factors for comprehensive consideration, to determine a reasonable process parameters. The following are the principles and scope of selection of these parameters: 1. Annealing temperature: annealing temperature refers to the steel pipe in the annealing furnace heated to the highest temperature, which determines the degree of dissolution of various phases in the steel pipe, affecting the corrosion resistance, plasticity and toughness of the steel pipe. Generally speaking, the higher the annealing temperature, the more fully dissolved in the various phases of the steel pipe, the better the corrosion resistance and formability of the steel pipe, but too high a annealing temperature will also lead to excessive growth of the grain, reduce the toughness and strength of the steel pipe, and even cause overcooking phenomenon, so that the steel pipe loses its value. Therefore, the annealing temperature should be selected so that the various phases in the steel pipe is fully dissolved, and will not cause excessive growth of grains within the range.
2. Insulation time: insulation time is the time that the steel pipe is kept at the annealing temperature, which determines the dissolution uniformity of the various phases in the steel pipe, affecting the organization of the steel pipe uniformity and performance consistency. Generally speaking, the longer the insulation time, the more uniform the dissolution of various phases in the steel pipe, the more consistent the organization and performance of the steel pipe, but too long insulation time will also lead to excessive growth of grains, reduce the toughness and strength of the steel pipe, and even cause overcooking phenomenon, so that the steel pipe loses its use value. Therefore, the insulation time should be selected so that the various phases in the steel pipe dissolved uniformly, and will not cause excessive growth of grains within the range. According to different steel pipe materials and specifications to determine the insulation time.
3. Cooling speed: Cooling speed refers to the cooling of steel pipe from solid solution temperature to room temperature.
