| The nonoxidizable stainless steel smelting process is the most important technology in numerous small and medium scale stainless steel foundries. Though it has many virtues, for example simple technics and low cost, it has a lot of shortcomings such as many non-metallic inclusions, poor mechanical properties and corrosive resistance because of lacking the ability of decreasing carbon and refining process. So, 18-8 type austenite stainless steel, which is a kind of stainless steel applied most extensively, under the most conditions, must be taken solution heat treatment to get good mechanics property and corrosion resistance. But the solution heat treatment of austenitic stainless steel has some characters such as high-temperature, larger energy-consumed and strong-distorted, which limit the application of austenite stainless steel. It has been reported that some trace alloying elements such as Zr, Nb and V can restrain the precipitation of carbides from grain boundaries under some special conditions. Therefore, it is possible to achieve casting available stainless steel without chromium carbides by adding these trace alloying elements.In this study, the influence of some trace strong carbide forming elements on the mechanical properties and corrosion resistance of 18-8 type casting stainless steel has been studied systematically on the basis of adding the self-made refiner. There are primary study contents as below: The effect of different zirconium contents on microstructure and properties of stainless steel is investigated. The function of zirconium element in the stainless steel is also analyzed.The effect of different niobium contents on microstructure and properties of stainless steel is investigated. The function of niobium element in the stainless steel is also analyzed. The effect of different vanadium contents on microstructure and properties of stainless steel is investigated. The function of vanadium element in the stainless steel is also analyzed.The effect of different carbon contents on microstructure and properties of stainless steel is investigated. The synergistic influence of different Zr,Nb and V contents with different carbon contents on the microstructure and properties of casting stainless steel is analyzed.Through measuring the mechanical properties, analyzing the microstructure and inclusions by optical microscope and electron microprobe and measuring corrosive resistance by H2SO4-CuSO4 intergranular corrosion test method, 65%HNO3 liquor intergranular corrosion test method and the FeCl3 liquor pitting corrosion weight-loss test, some conclusions are drawn as bellow:To micro-alloyed 18-8 type stainless steel, both the mechanical properties and intergranular corrosion resistance have been improved greatly; niobium addition can increase the mechanical properties and intergranular corrosive resistance of stainless steel; zirconium element has a good effect on ameliorating the shapes and distribution of inclusions in the steel, at the same time, it decreases the corrosive resistance; vanadium element has an advantageous but unobvious influence on the microstructure and corrosion resistance; It can alleviate the disadvantageous influence of high carbon content on corrosive resistance when some elements such as Zr, V and Nb exist in the steel; The proper alloying-element additions in the melting process should be confirmed according to the working condition and production cost generally.
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