The effect of Mn/N ratio on microstructural evolution, mechanical and fracture properties in welding heat affected zone (HAZ) of 22% Cr lean duplex stainless steel (DSS) were investigated. At comparative low heat inputs for low nickel tested DSS, the reformed austenite evolution of HAZ was mainly controlled by N content, and increasing Mn/N ratio promoted the growth of widmanstatten austenite (WA) and inhibited Cr₂N precipitates formation in HAZ, and then significantly reduced its strength and elongation due to weakened strengthening effect and the decrease of austenite fraction. The tensile and yield strength of HAZ for 17.80 Mn/N ratio DSS are higher than that of 2205 DSS, but the obstruction of dislocation movement resulted in a sharp decrease of plasticity at high heat input of 2.935KJmm^-1. The impact fracture of HAZ changed from ductile to brittle mode with the increase of Mn/N ratio, and for 17.80 Mn/N ratio DSS with high nitrogen content, the widening gaps of hardness and elastic moduli between two-phases in HAZ increased crack tendency, and significantly reduced its toughness. More grain boundary austenite (GBA) and WA formation for 51.14 high Mn/N ratio DSS segmented and refined the ferrite matrix in HAZ and improve impact toughness at higher heat input, while the coarsening of WA and (Cr, Mn) O oxides adversely reduced it to a lesser extent.

研究了 Mn/N 比对 22% Cr 贫铬双相不锈钢 (DSS) 焊接热影响区 (HAZ) 组织演变、力学和断裂性能的影响。在低镍测试 DSS 的较低热输入下，HAZ 的重整奥氏体演变主要受 N 含量控制，增加 Mn/N 比促进了威德曼氏体奥氏体 (WA) 的生长并抑制了 HAZ 中 Cr ₂ N 析出物的形成，并且然后由于强化作用减弱和奥氏体分数降低，其强度和延伸率显着降低。HAZ对17.80 Mn/N比DSS的抗拉强度和屈服强度高于2205 DSS，但位错运动受阻导致在2.935KJmm ^{-1高热输入下塑性急剧下降}. 随着 Mn/N 比的增加，HAZ 的冲击断口由韧性模式​​转变为脆性模式，对于 17.80 Mn/N 比的高氮 DSS，HAZ 内两相间硬度和弹性模量差距的扩大增加了裂纹倾向，并显着降低其韧性。更多的晶界奥氏体 (GBA) 和 WA 形成，51.14 高 Mn/N 比 DSS 分段和细化 HAZ 中的铁素体基体，并在更高的热输入下提高冲击韧性，而 WA 和 (Cr, Mn) O 氧化物的粗化不利地减少它在较小程度上。