Study On The Processing Property Of Domestic Petroleum Storage Tank Steel Plate

In order to speed up the construction of national strategic reserve base, our China has to build large floating roof tanks with a single storage volume greater than one hundred thousand, and which need a large number of steel plates. Heretofore, China always used steel plates made in Japan to build petroleum storage tank, it's expensive and could not guarantee the supplying time. Therefore, the State Development and Reform Commission strong request the localization of petroleum storage tank steel plate. But due to this kind of plate requiring high heat input welding more than 100KJ/cm, it's very difficult for industrial production. Thus, lots of techniques need to research and develop. Combining with NEU-Shouqin Metal Material Co., Ltd 4300mm wide heavy plate research platform, the present paper investigated technological properties of melting and et al., of newly rolled petroleum storage tank plate, systematically. The main works involved as follows:(1)Studied the effect of heat treatment parameters on structure and mechanical properties of industrial trial rolled plate, under different temperatures by quenching and tempering experiment, and proper heat treatment temperature parameters were determined as: 930℃×30min quenching plus 660℃×60min tempering for 40mm thick plate; and 920℃×30min quenching plus 650℃×60min tempering for 40mm thick plate. This gave a basis for industrial heat treatment.(2)The effect law of welding heat input on the structure and property of the trial plate was investigated by welding thermal simulation test, and by which it could make sure that acicular ferrite was the main influence on the high heat input weldability. The results shown that 40mm thick plate did not bear high heat input welding, but even when the energy input up to 80KJ/cm, an acceptable property obtained for 21mm thick plate.(3)An experiment of high heat input welding was proceeded on double wires submerged arc welding equipment in the laboratory. By analyzing the structure and property in welding seam and heat affected area, the effect law of alloyed elements on weldability was investigated. It was found that when the practical energy input was 66KJ/cm, the properties of 21mm thick plate could meet the requirement of the standard.(4)The resistance of cold crack of 21mm thick plate was also investigated in this paper, by Y-slit type cracking test. The results showed that:under the preheating and slow cooling condition, the steel has excellent cold crack resistant ability.(5)Selected the same kind of steel plate produced in Baosteel and Japan, and used testing method depicted in (3), (4) and (5), a series of studies have been carried on, and the results were compared to that of the trial steel. Lower impact toughness was found in welding heat affected zone of trial steel. Furthermore, improvement measures were put forward according to several aspects, such as chemical constituents, smelting process, rolling process, heat treatment process and high heat input welding, and it provided a feasible method for next industrial experiment.