具有高强匹配焊缝金属的LDX2101钢接头显微组织表征

Microstructure Characterization of LDX2101 Steel Joint with High⁃strength Matching Weld Metal

综述了涉及高强匹配焊缝金属的LDX2101钢接头显微组织的特征。结果表明,节约型双相不锈钢LDX2101焊接材料的选用,可以采用“准成分匹配”选用原则,即焊缝中所加元素的种类与母材相同,但各元素的含量可能有较大的变化,以确保熔敷金属中具有适量的相平衡,获得满意的综合性能。相同的热循环条件下,接头的组织主要取决于化学成分,即Creq/Nieq比值;在一定范围内,随Creq/Nieq比值降低,提高了铁素体固溶温度,在较高温度下发生δ→γ转变,获得较多的奥氏体。随热输入增加,在所有焊缝金属中,γ奥氏体的含量增大,而且γ奥氏体的含量高于δ-铁素体的含量;在HAZ,随热输入增大,γ奥氏体的含量增大。在650℃时效试件中,焊接接头的组织变化主要是Cr2N析出;650℃时效15 min时,主要是铁素体晶内析出Cr2N;650℃时效90 min时,在接头3个区的晶界上均析出Cr2N。铁素体含量的变化:焊缝为37%,HAZ为40%,母材为45%。

The microstructure characteristics of LDX2101 steel joints involving high strength matched weld metals were reviewed.The results show that the principle of"quasi⁃composition matching"can be adopted in the selection of welding consumables for lean duplex stainless steel LDX2101,that is,the kinds of elements added in the weld are the same as those of the base metal,but the contents of each element may change greatly,so as to ensure proper phase equilibrium in the deposited metal and obtain satisfactory comprehensive properties.Under the same thermal cycling conditions,the microstructure of the joint mainly depends on the chemical composition,that is,Creq/Nieq ratio.In a certain range,with the decrease of Creq/Nieq ratio,the solid solution temperature of ferrite is increased,andδ→γtransformation occurs at higher temperature,and more austenite is obtained.With the increase of heat input,the content ofγ⁃austenite in all weld metals increases,and the content ofγ-austenite is higher than that ofδ⁃ferrite.In HAZ,with the increase of heat input,the content ofγaustenite increases.In the 650℃aging specimen,the microstructure change of the welded joint is mainly Cr2N precipitation.When aged at 650℃for 15 min,the main precipitation is Cr2N within the ferrite grains.When aging at 650℃for 90 min,Cr2N is precipitated on the grain boundaries of the three regions of the joint.The change of ferrite content is 37%in weld,40%in HAZ and 45%in base metal.