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Sales hot rolled steel pipe Factory Quotes

Sales hot rolled steel pipe Factory Quotes

The spheroidizing annealing of the hot-rolled seamless steel pipe is to obtain a structure in which fine, small, uniform and round carbide particles are uniformly distributed on the ferrite substrate, and is prepared for the subsequent cold working and final quenching and tempering. The traditional spheroidizing annealing process is to keep the temperature slightly higher than Ac1 (for example, GCr15 is 780 to 810 ° C), and then slowly cool the furnace (25 ° C / h) to air cooling below 650 ° C.


This process has a long heat treatment time (more than 20h), and the carbide particles are not uniform after annealing, which affects the subsequent cold working and the final quenched and tempered structure and properties.


Then, according to the transformation characteristics of supercooled austenite, an isothermal spheroidizing annealing process was developed: after heating, it was quickly cooled to a temperature range below Ar1 (690-720 ° C) for isothermal, and the austenite orientation was completed during the isothermal The transformation of ferrite and carbide can be directly air-cooled after the transformation is completed. The advantage of this process is that it saves heat treatment time (the whole process is about 12-18 hours), and the carbides in the hot-rolled seamless steel pipe structure after treatment are fine and uniform.


Another time-saving process is repeated spheroidizing annealing: first heating to 810 ° C and then cooling to 650 ° C, and then heating to 790 ° C and then cooling to 650 ° C for air cooling. Although this process can save a certain amount of time, the process operation is more complicated.


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