Application characteristics of P91 seamless pipe

Thick wall P22 seamless alloy pipe is a new type of ferritic steel, similar to stainless steel. As an ideal boiler steel in the temperature range of 600-650 ℃, it is widely used in high-capacity thermal power generating units all over the world. P22 seamless alloy pipe, especially the supercritical unit developed in recent years, has the comprehensive properties required by its main steam pipe, hot reheat steam pipe and its corresponding high-temperature header steel. P91 steel has become a material because of its high normal temperature mechanical properties, high-temperature instantaneous properties and high-temperature properties.

The steel was and improved in the mid-1980s, and began to be applied in developed countries such as Europe and Japan in the 1990s. In recent years, it has been introduced to China and localized. At present, our company has been able to independently produce seamless tube blanks of this material. As a process to determine the end use performance of the product, heat treatment is optimized in the process of continuous exploration and improvement, so as to obtain good comprehensive mechanical properties. However, as the developed high alloy seamless tube blank, there are coarse grains and mixed grains after heat treatment.

At the initial stage, the bad grain size of P91 alloy seamless pipe is not used as the acceptance basis, but only the reference data. With the gradual improvement of ordering seamless alloy tube manufacturers and technical agreement requirements, and the revision of the new standard, the grain size of seamless tube blank of this kind of material was also included in the product acceptance index at the end of 2010. In view of this increasingly prominent problem, based on continuous exploration and improvement, analysis and utilization of the material and its manufacturing and processing characteristics, and combined with the actual production conditions, the annealing process of the seamless tube blank of the material is optimized.