LFC analysis of various defects - the cause of the collapse of the box when the cause of the collapse of pouring pouring a lot of boxes: a splash when pouring molten steel so serious that the box opening sealed LOI serious film, box mouth exposed surface increases, damage sand box sealed vacuum heat-resistant steel, a sharp decline in the degree of vacuum. 2 casting speed is too slow, especially in the case of drying casting, molten steel can not be sealed sprue crossing, crossing large amount of gas sucked from the sprue, the degree of vacuum of a sharp decline in the sand box. Original vacuum level 3 sand box set too low, especially due to the barrier effect of the appearance of deep cavity wall, a lower degree of vacuum. 4 pouring scheme unreasonable. When the top-pouring of large, easily lead to instant gasification gas can not be excluded from the sand outside the box case, the sandbox vacuum reduction. 5 vacuum pumping system is poor, gauze plugging, plugging the pipeline, pump water level low enough so may result in pumping capacity. Dry sand dust too. 6 model casting in sand box unreasonable position, spans the gap is too large. 7 release coating strength is not enough sand. Paint thinner intolerance erosion. Element effect of alloying elements chromium, aluminum, silicon, these ferrite formation at high temperatures can cause a dense metal oxide film formed on the surface, to prevent further oxidation, the main elements of the steel to improve resistance to oxidation and high-temperature gas corrosion. However, aluminum and silicon content is too high room temperature ductility and thermoplastic serious deterioration. Chromium can significantly improve low alloy recrystallization temperature, content of 2%, the reinforcing effect is best. Nickel, manganese can be formed and stabilized austenite. Ni austenitic steels to improve high-temperature strength and improve anti-carburizing. Although manganese austenitic heat treatment may be able to form a nickel producers, but harm the oxidation resistance of heat resistant steel. Vanadium, titanium, niobium are strong carbide forming elements, can form a fine dispersion of carbides, high temperature strength of steel. Titanium, niobium and carbon bond also prevents austenitic steels at elevated temperatures or intergranular corrosion after welding. Carbon, nitrogen can expand and stabilize austenite, thereby improving high-temperature strength heat-resistant steel. Steel contains chromium, manganese more heat-resistant steel manufacturers, can significantly increase the solubility of nitrogen in Shandong heat-resistant steel, and the use of nitrogen alloyed to replace the more expensive nickel. Boron, rare earths are heat resistant steels in trace elements. Boron manipulation dissolved solid solution crystal lattice distortion, boron grain boundary diffusion can stop elements and grain boundary migration, thereby improving the high temperature strength of steel; rare earth elements can significantly improve the oxidation resistance of the steel, thermoplastic improve. Heat-resistant steel can be divided into four categories according to their organization: pearlite steel: alloying elements chromium, molybdenum based, generally not more than 5% of the total. In addition to its organization pearlite, ferrite in vitro, as well as bainite. Such steel has in the 500 ~ 600 ℃ good high temperature strength and process performance, low price, widely used in the production of heat-resistant parts below 600 ℃. Such as boiler pipe, steam turbine impeller, rotor, fasteners and pressure vessels, piping, etc. Typical steel grades: 16Mo, 15CrMo, 12Cr1MoV, 12Cr2MoWVTiB, 10Cr2Mo1,25Cr2Mo1V, 20Cr3MoWV like. Heat treatment manufacturers, heat-resistant steel, Public Li Xin machinery companies from Linyi Public Li Xin Machinery Limited. Road Zhiyuan, temper forward. Linyi Public Li Xin Machinery Co., Ltd. (www.lyzlx.com) aims to become and you win symbiosis, strategic partners to move forward, more determined to become the most influential enterprises casting, and you leap together to success!