P91 High Alloy Steel Continuous Casting Billet Solidification Structure And Mechanical Properties After Research

P91/T91steel is a new martensitic steel, developed by the Oak Ridge National Laboratory and The United States of America Combustion Engineering Company. P91steel has good hot strength, oxidation resistance and corrosion resistance, widely used as a steam pipe and other important high-temperature pressure components.P91steel is mainly concentrated in the microstructural of welding area and influence of alloying elements, but the reports about the microstructure and properties the P91steel in solidification is rare. In-depth study of the steel process, organizational control and We argue the P91steel continuous casting ingots of Hengyang Valin Steel Tube Co.Ltd to study phase transformation and microstructure alloy element distribution during solidification.(1)combined with optical microscopy and scanning electron microscopy, we analyzed the microstructure of P91continuous casting ingots after solidification, finding that in the center of the ingot, the microstructure was consisted of ferrite and martensite, while away from the center towards surface, the volume fraction of ferrite was continuously reduced until disappear somewhere around middle portion where that of martensite being increased.(2)combined with chemical analysis and energy spectrum, we analyzed alloy element distribution in P91continuous casting ingot after solidification. The result show that the distribution of alloying elements in the ingot is uniform, without solidification temperature, cooling rate and location.(3)by the surface hardness and tensile tests on the P91continuous casting ingots after solidification, we found that the hardness of increase from the center towards surface. With the poor plastic, it’s difficult for P91continuous casting ingots to process.(4)The residual stress was tested using X-ray Stress Testing Instrument and the result presented was determined to be thermal stress with740MPa tensile stress appeared in the inner part (center) while435MPa compressive stress occurred in the outside (surface).