Study On Wear Resistance Of The Electrodes Of Cr13 Alloy System For Valve Sealing Surface

As important parts, valves are widely used in various industrial sections, such as oil refinery, power plant, nuclear power station, fertilizer factory etc. In the application of Valves the different forms of failure such as causing leakage, stopping production, out of control, and other fatal accidents to property and personal safety have been brought about to cause immeasurable loss. It can be seen that the quality of the valves will have a direct impact on national economic development. For a long period of time, sealing surface is suffered from corrosive wear, erosion, friction and wear between the sealed pair. But abrasion of sealing surface is an important factor to affect the valve service life. Therefore, in order to increase the quality of valves at the beginning, to increase corrosion and wear resistance of sealing surfaces should be done. And according to service circumstance the overlying materials are chosen against high temperature, corrosion or wear, then to increase sealing surface bearing the ability of bad work condition.Surfacing is a kind of processes by which metal layers to bear wear, corrosion and other special function on metallic materials or part surfaces are prepared. As a kind of economic but fast craft method in surface modification technologies of materials and renovating and surfacing is just a valid path to increase the ability of corrosion, wear and thermal resistance. Therefore, surfacing is a common method for repairing in production. This requests to research different kinds of high-quality valve electrodes to accommodate the demand of all kinds of work condition. This thesis puts forward the goal of increasing wear ability of middle and high pressure valve, intending to research to a new kind of Cr13 alloy system electrodes. It's based on 2Cr13 alloy coating, adding certain alloy chemical elements of V, Mo, C, Cr,Ti etc. ,and systematically studying the effect of different alloy elements on hardness and wear ability of surfacing layers. The compositions, microstructures and properties of the surface layers and their regular patterns are analyzed and summarized by surveying macromorphologies, composition and microstructures and macro-hardness measurement and erosion test.In the initial development of electrode coatings, the 4th coating gives a comprehensive good performance. Its core is H08A and slag system is combined with CaO-CaF2-SiO2. When welding, property of slag coverage is better than that of the 3rd electrode, with good formability of landscaping, arc stability, easily wiping slag off simultaneously.On the condition of single-factor experiment,the law of the surfacing wear resistance is affected by alloying elements as following: increasing C content of surfacing layers decreases weight loss gradually, and compared with 90°experimental conditions ,variable of grinding weight loss on 30°experimental conditions is bigger. Different contents of Mo addition can improve the wear resistance of surfacing overlay, and for the same sample, wear resistance of surfacing layers at large angle erosion conditions is better than one at small condition. With increase of V in Cr13 system, wear resistance of surfacing layers increasing and dropping trend is the same at both erosion angles, and weigh loss reaches the maximum at 2.08% V, and its inverse proportion is 2.1﹕1.From the curve of Cr content to weight loss, at 90°erosion experimental conditions, range of weight loss is wide, and the greatest weight loss of 26.4㎎, minimum weight loss of 6.8㎎. Thus Cr plays a critical role at improving the wear resistance of surfacing overlay.On the condition of orthogonal experiment, 30°angle erosion, compared with D516Mn electrode, except 45 mark, wear resistance is developed by the welding rod coverings among them wear resistance of 43, 42, 46 three formulas is improved obviously, which increased volume is about 50 percent bigger than the wear resistance of D516Mn electrode. At 90°erosion, compared with D516Mn rod cladding layer, wear resistance is improved by the welding rod cladding layers of this thesis at different erosion angles. Among all the orthogonal experiments, the wear resistance of 47 mark has the most prominent performance, itsεA=1.83。It proves that the surfacing electrodes have wonderful metallurgy behavior by testing measurement and analyses. Compared with D516Mn rod cladding, the wear resistance of experimental cladding layers is improved obviously.