Alloy steel pipe, alloy steel tube,  annealing temperature

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Effect of annealing temperature on properties of alloy steel pipe

12Cr1MoVG alloy seamless pipe is mainly seamless steel pipe for high-pressure chemical fertilizer and petroleum cracking. In recent years, with the continuous launch of new or expanded petroleum refining and petrochemical projects, the market space of cracking pipes used in petroleum refining and petrochemical units is increasing, resulting in that the output of domestic petroleum cracking pipes is far from meeting the market demand. At the same time, with the development of chemical industry, the demand for seamless steel pipe for high-pressure chemical fertilizer is increasing. Therefore, aiming at the urgent needs of petroleum industry and chemical industry, 1crsmo seamless alloy pipe for high pressure chemical fertilizer and petroleum cracking was.

As we all know, 1crsmo alloy steel has bainite structure of 380hb under rolling and air cooling conditions, with low plasticity and toughness, which can not meet the needs of petroleum industry and industrial fertilizer production. Therefore, annealing treatment is carried out. In this paper, through the heat treatment process of the steel, the heat treatment process whose performance indexes meet the standard requirements and technical conditions is selected, and the heat treatment system is applied to the on-site batch production.

Technical requirements

According to the standard requirements, the chemical composition requirements of 1crsmo seamless steel pipe for high pressure chemical fertilizer and petroleum cracking.

Heat treatment system and experimental results

The heat treatment system of 1crsmo alloy seamless pipe is annealing treatment. The AC point of 1crsmo alloy steel pipe is 770 ~ 790 ℃, and the AC3 point is 830-850 ℃.

The furnace charging temperature is 750 ℃, the annealing temperature is 800 ~ 980 ℃, the heat preservation is 2h, and the furnace is cooled to 650 ℃ for air cooling. Mechanical properties of 1crsmo alloy steel pipe at different annealing temperatures. Effect of annealing temperature on yield strength, tensile strength, elongation, impact energy and Brinell hardness.

With the increase of annealing temperature, the yield strength, tensile strength and Brinell hardness decreased in Nanchang, and the impact energy and elongation increased with the increase of annealing temperature; It can be seen from the table that various non-metallic inclusions are grade 0.5 ~ 1.0, the grain size is grade 8.08.5, and the microstructure after annealing is pearlite + ferrite.

Effect of annealing holding time on properties

Charging temperature is 750 ℃, annealing temperature is 880 ℃, 900 ℃, holding for 12.5h, cooling to 650 ℃ with the furnace and air cooling. Mechanical properties of 1crsmo alloy steel pipe under different annealing and holding time. Effect of annealing holding time on yield strength, tensile strength, elongation, impact energy and Brinell hardness.