Thermal treatment method for inhibiting and eliminating banded structure in low-alloy and heatproof steel tube
The invention provides a thermal treatment method for inhibiting and eliminating a banded structure in a low-alloy and heatproof steel tube. The method comprises the following steps: sampling low-alloy and heatproof steel tubes which are subjected to smelting and rolling, performing metallographic structure observation and grading the banded structure; machining the low-alloy and heatproof steel tubes which are rolled in a thermal mode to manufacture a cylindrical sample with the diameter of 3mm and the length of 12mm, and welding a K-type thermocouple in a central position along the length direction of the cylindrical sample; heating at a warming speed from the temperature of 20-50 DEG C to 880-910 DEG C and performing heat preservation for 8 minutes to ensure that the cylindrical sample structure is completely austenitized; cooling the cylindrical sample at the cooling speed of 20-100 DEG C/S by jetting nitrogen at a high speed; performing air cooling on the cylindrical sample till reaching the room temperature. The method has the beneficial effects that by using the thermal treatment method, the structure after thermal treatment is a ferrite pearlite, and the banded structure formed in the hot-rolling formation process can be effectively eliminated, and the increase of the production cost is avoided, so that the method is an economic and effective treatment method. 1. A for inhibiting and eliminating low-alloy heat-resistant steel strip in the heat treatment method, the method includes the following steps: 1) the smelting, rolling into the steel tube of the low-alloy heat-resistant steel tube sampling, to observe the metallographic structure, and the strip-like organizations in accordance with the National standard GB/T13299-91 rating; 2) after the hot rolling of the low-alloy heat-resistant steel tube to carry out mechanical processing, to make a diameter of 3 mm, a length of 12 mm of the cylindrical sample, is processed through the thermal expansion test: first, the K-type thermocouple is welded along the columnar shape in the length direction of the center position of the sample, is used for measuring the temperature change of the cylindrical sample; then in order to temperature the 20-50 [...] /min is heated to the temperature rising rate of the 880-910 [...] and thermal insulation 8 minutes, in order to ensure that complete austenitization cylindrical sample organization; subsequently cylindrical the nitrogen through the injection at a high speed in order to sample the 20-100 [...] /S cooling rate of cooling to a temperature the 600-630 [...] ; and then the cylindrical sample is air-cooled to room temperature.