层间温度对超级双相不锈钢SAF2507模拟热影响区组织转变规律及力学性能的影响

Puting forward a testing method of heat affected zone considingthe actual welding heat affected zone is too narrow and not accurate test evaluation problem. In this work,the effect of interpass temperature on microstructural development and mechanical property within the heat affected zone (HAZ) of SAF2507, which was simulated by gleeble 3 800 thermal simulation machine was studied. The results indicated that the proportion of α/γ is close to 1:1 and there is no widmanstatten austenitic or intermetallic phase precipitation existed when interpass temperature is 150 ℃, but secondary austenite and widmanstatten austenitic precipated from the grain boundary or within the grain and grow up while the hardness decrease and impact toughness increases with the increasing of interpass temperature. χ phase appeared when the interpass temperature reached to 250 ℃. While the interpass temperature reached to 300 ℃, the hardness increased and impact toughness decrease becaused of a large number of σ phase which were observed by SEM and EDS precipitated. Therefore, to maintain the good phase proportion of α/γ and mechanical properties in the actual welding join, the interpass temperature should be no greater than 150 ℃.