不锈钢波纹管膨胀节应力腐蚀研究进展

波纹管膨胀节是现代动力管网和设备进行热补偿的关键部件之一,其作用除了位移补偿外,还兼有减振降噪和密封的功能。波纹管膨胀节不仅广泛应用于石油、化工、冶金、电力、原子能等工业部门,还应用于机车、船舶、城市燃气和民用部门。本文详细阐述了不锈钢波纹管组织结构、形变马氏体含量分布、残余应力分布。不锈钢波纹管在加工、成型过程中,波峰波谷会发生塑性变形,一部分奥氏体组织转变为马氏体组织,马氏体含量在波峰处最高,在波谷最低,均为拉应力。试验研究结果表明,波峰残余应力大,波谷小,固溶处理后残余应力变为压应力。残余应力越大,马氏体含量越高,不锈钢SCC敏感性大;直径小的波纹管,波峰曲率半径小,变形量大,故其残余应力和形变马氏体含量大,SCC敏感性大,易开裂。

Study on stress corrosion testing of bellows in public pipes

Bellow expansion joints is one of important parts in power and chemical equipment and pipe,it has many advantages such as stopping abbreviation and mechanical sealing.It is also widely used in not only petroleum,chemical engineering,met allurgy,nuclear industries,but also automobile,ship,fuel gas and family usage etc.In this paper the micro-structure, marsentite percentage,residual stress distribution of stainless steel bellows were introduced in detail.Stainless steel bellows peaks and troughs could produce plastic deformation in process and forming, then ammonia would change into marsentite.Marsentite percentage in peak was the highest,and in trough was the lowest.The residual stress in peak was more than that in trough and they were all belongs to tensile stress.The result showed that the main residual stress were transformed to compressive stress by solution treatment. The more residual stress and marsentite percentage were,the more stainless steel SCC sensitivity was.The small diameter bellow has a small curvature radius and a great deformation,so it＇s residual stress and marsentite percentage was greater,and the SCC sensitivity was also greater.