材料期刊网

对一种新型镍基耐蚀合金(X-2#)与304奥氏体不锈钢手工氩弧焊接接头进行拉伸性能和硬度的测试,并结合OM,SEM和EDS等手段,系统研究了焊接接头的组织和力学性能.结果表明,X-2#/304异种金属焊接母材晶粒尺寸为40～65 μm,有利于异种钢的焊接;X-2#合金一侧熔合区未发现焊接缺陷,而304奥氏体不锈钢一侧有铁素体析出,铁素体中富Cr贫Ni;重熔区附近与靠304奥氏体不锈钢一侧的热影响区晶粒长大严重.X-2#/304异种金属焊接接头热影响区的Vickers硬度最小.X-2#/304焊接接头室温拉伸断裂位置在焊缝区,而高温拉伸断裂位置在304奥氏体不锈钢基体.由于A1,W和Mo元素的强化作用,X-2#合金的高温力学性能优于304奥氏体不锈钢.

With the fast development of industry,a serious global problem,pollution,becomes more apparent.A large number of wastewater is discharged,causing the environment pollution.Supercritical water oxidation (SCWO) becomes the most effective method to treat the wastewater within recent years,but the material used in the equipment plays a key role in restricting the application of the SCWO process.Currently,during the SCWO wastewater treatment process,304 austenitic stainless steel,alloy 625,P91 and P92 steels are the mainly preheater and reactor materials.In order to reduce the serious corrosion and improve economic efficiency of the materials for this process,a new corrosion resistant Ni-based alloy (called X-2# alloy) has been developed with an aim of replacing the previous ones.In particular,it is highly important to the related behavior of this new alloy welding with the original SCWO.Therefore,the microstructure and mechanical properties of the welding joint of the new alloy and 304 austenitic stainless steel with manual argon arc welding were investigated.The microstructure and fracture morphologies of the welding joint were analyzed through OM,SEM and EDS,and the detailed analysis of the micro-hardness,tensile strength and other mechanical properties were performed.The results demonstrated that the parent material with the typical 40～65 μm grains size is helpful for dissimilar steel welding,and the microstructure in fusion zone of X-2# side does not show welding defects.However,some ferrites are further formed near the fusion zone of 304 stainless steel sides.There are Cr-rich and Ni-poor distributions in the ferrites.The grain grows seriously in both the areas near the remelt zone and 304 stainless steel side of heat affected zones (HAZs),which affect heavily the performance of welding joint.In addition,the results also uncover that the Vickers-hardness is the minimum in the HAZ.At room temperature,the fracture location of the tensile tests of X-2#/304 is in the welding seam,whereas at 500 ℃ the corresponding position is in the 304 matrix.Due to the strengthening effects of Al,W and Mo elements,the high temperature mechanical properties of X-2# alloy have been found to be even better than those of the 304 austenitic stainless steel.