摘要
为探索大型石化筒体根部止口的制造新工艺,采用新研发的2.25Cr-1Mo-0.25V合金丝材,使用CMT电弧熔丝增材制造技术首次堆积2.25Cr-1Mo-0.25V直壁墙,探索增材后的最佳热处理工艺,以改善沉积态显微组织与力学性能。实验发现:增材成形的直壁件内部微观组织主要为板条贝氏体、粒状贝氏体和部分马氏体,堆积方向组织差异明显,显微硬度浮动剧烈,拉伸强度远高于母材,但断裂延伸率较低。对增材后的直壁件施加“消氢处理+去应力处理”和“模拟最小焊后热处理”,发现后者能将其塑性提升至与母材相当。根据显微组织分析,经过“最小焊后热处理”,沉积态的板条贝氏体和部分马氏体可转变成均匀分布的粒状贝氏体,组织间的各向异性显著降低。实验证明,应用新研发的2.25Cr-1Mo-0.25V丝材在最佳的CMT电弧熔丝增材工艺参数下成形直壁件并结合“最小焊后热处理”能够最大程度地改善显微组织和力学性能,最终满足石化容器筒体根部止口的服役指标。相比浇铸-锻造成形止口的工艺,开发的CMT电弧熔丝增材新工艺有望大幅节约生产成本,提高制造效率。
In order to explore the new manufacturing processes of large petrochemical cylinder root edges,a newly self-developed 2.25Cr-1Mo-0.25V flux-cored wire was firstly used to deposit 2.25Cr-1Mo-0.25V straight-walls based on cold metal transfer and wire arc additive manufacturing(CMT-WAAM),and the best post-weld heat treatment was explored to improve microstructure and mechanics properties.The experimental results show that the internal microstructure of the straight-walls deposited by CMT-WAAM are mainly composed of lathy bainite,granular bainite and some martensites,with obvious differences in the building direction,dramatic floating micro-hardness and much higher tensile strength than that of the base metal,but lower fracture elongation.After applying“hydrogen elimination treatment+stress relief treatment”and“simulated minimum post-weld heat treatment”on the deposited walls,the latter was found to increase the plasticity to a level comparable to the base metal.Microstructure observations reveal that original lathy-bainite and partial martensite may be transformed into the uniformly distributed granular bainite after the“minimum post-weld heat treatment”,and the microstructural anisotropy may be significantly reduced.The experiments prove that the newly developed 2.25Cr-1Mo-0.25V wire may be used to deposit straight-walls under the optimal parameters,the subsequent“minimum post-weld heat treatment”may improve microstructure and mechanics properties to the greatest extent,which finally meet the service specifications of petrochemical vessel root edges.Compared with the casting-forging processes,CMT-WAAM is expected to significantly save production costs and improve manufacturing efficiency.
作者
仲杨
秦晓波
郑志镇
李建军
王承
ZHONG Yang;QIN Xiaobo;ZHENG Zhizhen;LI Jianjun;WANG Cheng(Department of Materials Science and Engineering,Huazhong University of Science and Technology,Wuhan,430074;Erzhong(Deyang)Heavy Equipment Co.,Ltd.,Deyang,Sichuan,618000)
出处
《中国机械工程》
EI
CAS
CSCD
北大核心
2022年第10期1251-1259,共9页
China Mechanical Engineering
基金
国家重点研发计划(2018YFB1106501,2018YFB1106505)。
