材料期刊网

测试一种新型镍基耐蚀合金(X-2#)手工氩弧焊接接头的拉伸性能和硬度,并结合OM,SEM和EDS等技术研究焊接接头的组织和性能.结果表明,X-2#合金焊接接头焊缝区为铸态组织,熔合区从基体到焊缝金属组织过渡良好,热影响区没有晶粒明显粗化现象,母材晶粒尺寸约为65 μm,有利于接头的焊接.新合金焊缝区的Vickers硬度小于基体,但焊缝重熔区的硬度由于等轴晶数量增多而变大.合金中W和Mo等固溶强化元素及A1和Ti沉淀强化元素使X-2#合金焊接接头具有较好的高温强度及热稳定性.合金焊接接头室温与高温下的抗拉强度均低于母材,焊接系数η大于88％,焊缝区为接头最薄弱环节,拉伸断口均为韧性断口,断裂机制为正断与剪切断的混合断裂.

Industrial wastewater shows the characteristics of high concentration,complex composition and difficulty to degrade.Supercritical water oxidation (SCWO) gains extensive attention and application in wastewater treatment.This method ofwastewater treatment is carried out in the high temperature,high pressure,strong corrosion and oxidation conditions.Thus,the corrosion resistance of the materials used in the treatment equipment should possess excellent performance.Especially for the preheater or reactor piping material,the problem is more outstanding.In this work,a new corrosion resistant Ni-based alloy used in supercritical water oxidation environment was investigated.The microstructure and fracture morphologies of the welding joint were observed and analyzed by OM,SEM and EDS,and the microhardness,tensile strength and other mechanical properties were tested as well.The results indicate that the welding seam of the alloy welding joint can be categorized into cast structure.The microstructure of fusion zone has no welding defect,and the heat affected zone (HAZ) has no grain coarsening phenomenon.The grain size of the alloy is 65 μm.The Vickers hardness of the alloy welding seam are less than the matrix.However,as the number of isometric crystals increases,the Vickers hardness of welding remelting zone becomes large.Because of including W,Mo,A1,Ti in the alloy,X-2# alloy welding joint has good high-temperature strength and thermal stability.Due to the tensile strength of welding joints in the new alloys is lower than the parent materials,the welding seam is the weakest link.The tensile tests at room temperature and high temperature show tenacity fractures,and the fracture mechanism is mixed with normal fault and shear fault.