Hot Crack Tendency of 05CuPCrNi Steel

Hot cracks are generated at high welding temperatures. When crystallized, the eutectic with low melting point forms a liquid film, which will lead to cracking under the action of stress, hot cracks are mainly closely related to S, Ni, Mn, etc.

316L and 05CuPCrNi steel have a certain tendency of thermal cracking when welding, the main reasons are:
①The thermal conductivity of 316L stainless steel is smaller than that of 05CuPCrNi steel, but the coefficient of linear expansion is much larger, so greater stress will be generated in the joint after welding;

② 316L contains more Cr, Ni and other elements, and 05CuPCrNi contains higher S and P contents. 316L is easy to form low melting point eutectic with S and P near the seam. For example, the melting point of Ni-Ni3S2 is 644°C, and the melting point of Ni-Ni3P is 880°C. The existence of these eutectics with low melting point can promote the formation of hot cracks. Since 05CuPCrNi steel contains 0.093% P element, it is easy to weld with Ni forms a eutectic with a low melting point, leading to generation of hot cracks.

When 05CuPCrNi steel welding, the use of small welding heat input, multi-layer welding and reasonable welding sequence will help reduce the tendency of thermal cracks.