Despite the tremendous development of casting skills and the use of computer skills to assist in optimizing the structural planning and fluid geometry planning of the casting process, it is still extremely difficult to reach Class 1 or 2 to withstand standard X-ray / MT or PT quality requirements These are the standards required by the harsh environments of nuclear, thermal or petrochemical industries. Therefore, it is necessary to improve the aluminum mold for welding the rotor. However, after welding repair, the overall quality and reliability of the casting valve becomes difficult to ensure. Sometimes all these problems are left in the welded metal frame of the casting. Test rods are generally for each temperature, but their analysis may be uncertain. Even if the round test rod indicates that the chemical and physical properties are tolerable, the step itself may still have internal defects that are difficult to detect, such as loss of strength or corrosion resistance. .According to the requirements of Section IX of the boiler code for regular inspection, the contents that need to be inspected regularly in the course of use include repair welding of casting metals and pipe welds. Records of welding repair positions must therefore be kept, so during the operation of the factory, the occurrence of problems may be related to the original production conditions and standards. During the casting process, the metal cast into the mold cavity may shorten, detach or pores during the condensation process. These problems make the "casting" castings unbearable in harsh environmental applications. The shortening occurs in two processes, with the metal above the melting point shortening as it cools, and then further shortening during the condensation process. Adding molten metal compensation, but the compensation in the solid-state cooling process depends on increasing the scale. . Separation, or chemical separation of the melt, occurs during the condensation process after the inner wall of the mold cavity has solidified. During a long temperature change, the low activity causes small solid particles-crystals-to form a tree structure and Grow. Close to the inner wall of the cavity, the alloy content is small. In the center part of the inside, the alloy content is relatively high, which makes the expected composition have no similarity. Within each crystal branch, there is also microsegregation. The results lead to microporosity, regeneration phase deposition, and turbidity of metallic and non-metallic components. During the cooling process, the gas in the solution escapes to form porosity, or is trapped between the crystal branches to form fine pores. In addition, as the crystal solidifies and the amount is shortened, the substitute for the melt must flow a tortuous path along the interlaced crystal network. The resistance to movement may be too high, resulting in microporosity and porosity. Some other defects inside the casting are the clear cracks and hot tears appearing during the coagulation process under the combined effect of the unevenly shortened stress concentration and the low strength of the metal near the melting point. Lower casting temperatures can create cold scars, and accumulation of sand or slag from molten metal can cause stains. Elementary casting operations may also pose other drawbacks. The improvement of castings to meet the requirements of X-ray quality depends on grinding, welding repair, heat treatment and repeated testing and inspection of defective parts. Even in this case, the seat and gasket faces or bump ends may show fine wire cracks that need to be re-welded and machined.