The split flange of steam turbine cylinder block steel casting is the upper and lower half of the cylinder block. Ultrasonic flaw detection is required after the split is processed to meet JB / t9630 2 according to the level 2 requirements of ultrasonic flaw detection and quality classification method for steam turbine steel castings, there shall be no defects affecting product quality after flange drilling.
After ultrasonic flaw detection, the steam turbine cylinder block castings produced by ZHY casting have defects such as porosity and porosity between the risers of the split, high repair rate and high production cost, which seriously restrict the delivery time. Taking the middle cylinder block steel castings for a steam turbine as the research object, the casting process of the cylinder block is systematically studied by using numerical simulation technology and ultrasonic flaw detection results. After several improvements, the casting defects in the middle split of the cylinder block are solved.
In view of the casting defects such as looseness between the split risers of the steam turbine cylinder block, the connection between the risers is used as the riser subsidy or the integral riser is used on the flange surface, which effectively solves the loose defects in the split flange of the steam turbine cylinder block steel castings, and the casting quality fully meets the requirements of ultrasonic flaw detection, so as to improve the production efficiency and speed up the production progress.