What is the production process of the elbow

　　During the heating and cooling process for Stainless Steel Elbow, due to the difference of cooling rate and time between the surface and the core, the temperature difference will cause stress and thermal expansion. Under the action of thermal stress, because the surface temperature is lower than the heart and the contraction is larger than the heart, the heart is pulled. When the cooling is over, the surface tension of the surface is pulled down because of the final cooling volume contraction of the heart. That is, under the action of thermal stress, the surface of the workpiece is pressed and the heart is pulled.

　　This phenomenon is influenced by factors such as cooling rate, material composition and heat treatment process. When the cooling rate is faster, the carbon content and alloy composition is more high, the cooling process in the thermal stress under nonuniform plastic deformation, the final shape of the residual stress is bigger. On the other hand, during the heat treatment process for ASTM Bw Stainless Steel Elbow, because of the transformation of austenite to martensite during heat treatment, the volume expansion of workpieces will occur as the specific volume increases, and the locations of workpiece will undergo phase transformation.