Welding cold crack test of X80 pipeline steel
X80 pipeline steel is made of high strength and toughness by deformation strengthening, and X80 steel is also ultra-fine grain, high purity steel. Therefore, the steel puts special requirements on the welding process, mainly in how to prevent grain coarsening, local softening and embrittlement in the heat affected zone, how to achieve the purity of the weld metal and grain refinement, how to choose Welding methods and improved welding processes. Grain coarsening in the heat affected zone is an unavoidable phenomenon, and the grain growth weakens the performance of the welded joint. In order to control the grain growth of the heat affected zone of the pipeline steel at high heat input, the small welding heat input or high energy beam welding method is often used to narrow the coarse crystal zone so as not to affect the serviceability of the welded joint. However, cold cracks are likely to occur at the weld seam under small line energy. Therefore, it is necessary to preheat the wel...