基于平面压入技术研究焊接接头单轴应力-应变关系

目的 获取异种金属焊接接头母材和热影响区局部拉伸应力-应变关系。方法 对压水堆机组蒸汽发生器接管安全端异种金属焊接接头(20MND 5-INCONEL 52-Z2 CND 18.12控氮)进行研究，通过金相检验和显微硬度测试，研究DMWJ母材、热影响区、焊缝熔合线位置的金相组织和维氏硬度分布。采用等直圆棒拉伸试验获得DMWJ低合金钢(20MND 5)母材的应力-应变关系，采用基于能量等效理论的平面压入技术获得DMWJ低合金钢母材、热影响区和焊缝局部材料应力-应变关系。结果 DMWJ材料组织、力学性能不均匀，等直圆棒拉伸试验得到的低合金钢母材拉伸应力-应变关系与平面压入技术测得结果较为吻合。结论 基于能量等效理论的平面压入技术可精确测得DMWJ低合金钢母材、热影响区和焊缝局部材料应力-应变关系，对压水堆核电站DMWJ在役检测及结构完整性评价具有重要意义。

Exploration on Uniaxial Stress-strain Relationship of Welded Joint by Flat Indentation Method

The work aims to obtain the local tensile stress-strain relationship between the base metal and the heat affected zone of dissimilar metal welded joint (DMWJ). The DMWJ (20MnD 5-Inconel 52-Z2CND 18.12 nitrogen control) between the steam generator nozzle and the safe-end of Water Reactor was studied. Through the optical microscope and micro-hardness test, the micro-structure and hardness distribution of DMWJ base metal, heat affected zone and weld fusion line were investigated. The stress-strain relationship of the DMWJ low-alloy steel base metal was obtained by the straight round bar tensile test, and the local stress-strain relationship of the DMWJ low-alloy steel base metal, heat affected zone and weld was obtained by the flat indentation technology based on energy equivalence theory. The micro-structure and mechanical properties of DMWJ were not uniform. The tensile stress-strain relationship of base metal obtained by the straight round bar tensile test was in good agreement with the results obtained by the flat indentation technology. The local stress-strain relationship of the DMWJ low-alloy steel base metal, heat affected zone and weld can be accurately measured by flat indentation technology based on energy equivalence theory, which is of great significance for service inspection and structural integrity evaluation of DMWJ in the water reactor nuclear power station.