Fracture studies were carried out on bi-metallic pipe weld joints of 324 mm outer diameter having crack at different regions of weld in the circumferential direction. The bi-metallic pipe weld joints were made of low alloy steel (ferritic) and stainless steel (austenitic) materials. Welding consumable used was nickel-based alloy. The initial notch was located in the different regions of the weld joints such as base metals (ferritic and austenitic), centre of weld, buttering (nickel-based alloy on low alloy steel) and heat affected zones. Subsequent to fatigue pre-cracking, fracture tests were carried out under four-point bending under monotonic and cyclic loading. During the fracture tests, load, load-line displacement, deflections, circumferential deformations, surface crack growth, crack mouth opening displacement were recorded. In addition, number of cycles to failure were monitored for tests under cyclic loading. Under monotonic loading, collapse load of the bi-metallic pipe weld joint having initial crack in the centre of buttering reduced by 12% in comparison to the collapse load for crack in the centre of heat affected zone. Crack deviated towards austenitic region for the weld joints having crack in the centre of weld, centre of buttering and heat affected zone. The bi-metallic pipe weld joints subjected to cyclic loading failed at lower number of cycles even when the load amplitude was sufficiently below the collapse load under monotonic loading. Crack growth resistance of bimetallic pipe weld joints under cyclic loading was significantly lower compared to that under monotonic loading under displacement control.

对外径为324 mm的双金属管焊接接头进行了断裂研究，该接头在圆周方向上的不同焊缝区域均具有裂纹。双金属管焊接接头由低合金钢（铁素体）和不锈钢（奥氏体）材料制成。所使用的焊接材料为镍基合金。最初的缺口位于焊缝的不同区域，例如贱金属（铁素体和奥氏体），焊缝中心，黄油（低合金钢上的镍基合金）和热影响区。在疲劳预裂之后，在单调和循环载荷下在四点弯曲下进行断裂试验。在断裂试验中，记录了载荷，载荷线位移，挠度，圆周变形，表面裂纹扩展，裂纹口张开位移。此外，监视失败循环的次数，以进行循环载荷下的测试。在单调载荷下，与在热影响区中心的裂纹的崩溃载荷相比，在黄油中心具有初始裂纹的双金属管焊接接头的崩溃载荷降低了12％。对于在焊接中心，黄油中心和热影响区具有裂纹的焊接接头，裂纹向奥氏体区域偏移。即使在单调载荷下载荷振幅充分低于坍塌载荷时，经受循环载荷的双金属管焊接接头在较低的循环次数下也会失效。双金属管焊接接头在循环载荷下的抗裂纹扩展性比在位移控制下的单调载荷下的低。