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How to Avoid Defective Castings and Heat Treatment Standards in Valve Castings

Avoiding the occurrence of defective valve castings

When producing valve castings, attention must be paid to its production process. If not handled properly, it can reduce the product's corrosion resistance and affect its performance. Therefore, we need to pay special attention to the points that require attention during the manufacturing process. Those who are interested can learn more.

  • When casting valve castings, in order to prevent the occurrence of white spots, thicker stainless steel walls should be used in addition to taking measures in the process to ensure that the product does not have this phenomenon during use.

  • To facilitate the extraction of valve castings, the casting slope of the stainless steel casting should be larger than that of the sand casting, and the size of the inclination is not only related to the alloy type, but also to the position and height of the castings. A reputable sand casting factory can help in selecting the appropriate casting slope to produce high-quality valve castings that meet the required specifications. 

  • Because the cooling rate of metal molds is faster than other materials, it is necessary to control the temperature properly during manufacturing.

It can be seen that when producing valve castings, extra care must be taken to avoid substandard quality castings deteriorating quickly under corrosive media, rendering them ineffective. It is also recommended to use a larger wall thickness for the castings compared to sand casting, and to differentiate between good and poor quality products to avoid defects. Vacuum metal casting has emerged as a viable solution for tackling such challenges as it results in high-quality castings with improved surface finish, requiring minimal post-processing. By leveraging vacuum casting technology while maintaining stringent quality procedures and effective measures, manufacturers can produce high-performance valve castings that meet the highest standards of quality and durability.

Heat treatment standard for valve castings

In the casting process of valve castings, there is a step called heat treatment, which is an important process to improve the quality of valve castings. According to the different raw materials of the valve castings, different heat treatment standards will be required. Taking WC6 material as an example, this article will introduce the heat treatment standard for cast steel valve castings.

Heat treatment is a process in the casting process of valve castings, which can be subdivided into two processes: annealing and tempering. Valve castings need to choose the appropriate insulation time according to their wall thickness during both process. During annealing, the temperature in the furnace should be lower than 300°C, but it should be increased to 920°C at a rate of 100℃/hr, and the temperature fluctuation should not exceed 2℃. For valve castings with a wall thickness less than 50mm, the insulation time is 210-240min, and then increases by 60min for every 25mm.

The tempering process is similar to the annealing process, but the subsequent processing temperature upper limit is required to be 700℃, and the insulation time is determined by the wall thickness, starting from 240min and increasing by 30min units. Both processes are cooled by air cooling (due to the nature of cast steel).