Stainless Steel Casting Casting Performance
Stainless steel casting casting performance is poor, poor mobility, body shrinkage and line shrinkage larger, thermal stress, easy to produce cracks. Once the castings crack, not only the heavy workload, serious may also be scrapped, resulting in significant economic losses. Casting cracks in the main factors are casting structure, casting process, the production of the following measures to prevent the following:
Casting to fully consider the casting structure, shape, large, wall thickness and its impact on the casting liquid and solid shrinkage factors, select the appropriate process parameters to prevent shrinkage and other casting defects. Casting riser system design should be reasonable, if you want to use cold iron and other technical measures, the placement of the site to be reasonable, it is necessary to ensure the internal organization of the compact, but also try to avoid the stress concentration of the situation. 2, smelting 2, smelting process, try to reduce the P, S and other harmful elements, reduce the N, H, O and other gases and inclusions content. Through the use of low-phosphorus steel alloy, can play a very good effect.
Through the appropriate extension of the casting in the sand in the holding time, mainly to control the box temperature below 70 ℃, to ensure that the casting in the sand to fully complete the liquid and solid shrinkage, to avoid external factors caused by stress concentration occurs.
4, sand in the castings in the process of sand cleaning, is strictly prohibited when the box to the sand and casting watering, is strictly prohibited with a strong external shocks such as impact box sand, to avoid external forces and casting stress interaction between the cracks.
5, cut the riser
According to the casting conditions to select the appropriate thermal cutting riser process to ensure that the thermal start temperature of not less than 300 ℃. Operation, gas cutting torch and oxygen tube with vibration cutting. Important pieces of gas cut after the timely use of asbestos cloth cover or into the furnace heat treatment. For the crown and axial flow of a class of complex structure, the process to take special measures of the castings, the use of secondary thermal cutting.
6, warm up
In the stainless steel casting defect handling, to adhere to the principle of warm-up. In the blowing, welding process, the workpiece should be preheated to above 108 ℃ before operation. If you find a large crack defects, should be carried out to stress annealing, and then processed.
For a major stainless steel castings to be a final elimination of stress annealing process, strictly control the holding time and baked temperature. Its purpose is to reduce the production process to produce new stress concentration, more completely eliminate the casting stress, to prevent the occurrence of cracks.