火电厂600MW超临界机组用大直径热推A335P91弯头的力学性能探讨

Study on the Mechanical Properties of Induction Piercing Large-diameter A335P91 Elbow for 600MW SC Units

以火电厂600MW超临界机组用大直径热推A335P91弯头为研究对象,对该弯头进行了力学性能试验和相关项目检验。结果表明,该弯头无表面裂纹和晶间裂纹,其几何尺寸、壁厚、圆度等符合DL/T695-1999标准要求,弯头各部位常温和高温拉伸性能符合ASTM A335P91钢的要求。但由于应变硬化和鲍辛格(Bauchinger)效应的影响,使该弯头外弧和内弧力学性能存在明显差异。建议严格控制弯头扩径比,减小弯头推制过程中内外弧的塑性变形量,使弯头各部位获得最佳综合力学性能。

The mechanical tests and other related item tests for induction piercing large-diameter A335P91 elbow used in 600MW SC units were carried out. The results show that the elbow does not have any surface cracks and grain boundary cracks,its dimension,thickness,roundness,etc.are in accordance with the standard DL/T 695- 1999,and the mechanical properties both in room temperature and design temperature comply with the specification of ASTM A335P91.Owing to the effect of stress hardening and Bauchinger,the mechanical properties at the intrados and extrados of the elbow are obvious different.The author put forward the suggestion that the enlarge ratio of elbow diameter shall be strictly controlled and the plastic deformation shall be reduced during production so as to obtain optimum mechanical properties.