| The phosphoric-chemical industry play a very important role in the national economy. Its products like phosphoric acid, nitric phosohate and phosphate fertilizer, which are widely used. But the interaction between corrosion and abrasion, which leads to the short service life of the equipment in the phosphorous producing process, seriously restricts the smooth development of phosphoric-chemical. Developing and applying of new corrosion-abrasion resistant material according to the characteristics of this industry, can bring huge economic benefits to the enterprise.Based on the analysis of destruction of the pump cover and impeller of pump from the Shan Xi Tian Ji group used in the actual working condition, we succussed in designing a noval material named XDB-11 that can be used in the manufacture of phosphorus chemical industry equipment of duplex stainless steel. Including the chemical composition of alloy steel designing, melting and casting process improving, the heat treatment process designing, as well as electron microscopy, X-ray diffraction, scanning electron microscopy, mechanics experiment, electrochemical corrosion test and immersion corrosion test were applied to study on the structure properties of the duplex stainless steel XDB-11.Results show that the melting of the material contains austenitic and ferritic phase and the production of carbide.It is easy to cause intergranular corrosion to the materials. Therefore we chose to solution treatment, through the experiment result, we found that the harmful phase in the materials were eliminated under the condition of 1150 ℃ heating 4 h. At this point, hardness of the material is HRC22.1. In order to improve the hardness of materials, we did a large number of aging treatment, finally we found that solid solution treatment followed by aging treatment at 850 ℃ heating 3 h peak, the hardness can reach HRC43.4. At the same time,we found that in the the result of the corrosion experiment the performance if anti-corrosion is the order of solid solution treatment samples > aging treatment of metal samples > original casting sample.By using the σ phase as the second phase strengthening, the hardness of XDB-11 are improved without sacrificing the resistant corrosion performance. The highest hardness is obtained HRC43.4. Therefore, using weak negative poles of materials for the second phase strengthening, the designed material has excellent corrosion and abrasion resistance and can cope with phosphorus chemical equipment in the production process with complex conditions. |
PDF Full Text Request