Mo对高强度纯奥氏体气保焊丝熔敷金属力学性能的影响

The Influence of Mo on Mechanical Properties of a High Strength Pure Austenite Welding Wire Deposited Metal

测试了两种不同Mo含量的高强度纯奥氏体气保焊丝熔敷金属力学性能,并采用扫描电子显微镜对熔敷金属冲击断口和金相磨面微观形貌进行了观察,采用透射电子显微镜和XRD物相分析技术对第二相成分、结构进行了分析。试验结果表明,在该成分系下,随Mo含量的增加,熔敷金属强度有一定程度升高,但塑性和韧性均明显下降,主要原因是由于Mo的偏析,在晶界附近形成了Mo的富集区。随着Mo含量的增加,Mo的富集程度加剧,有力地促进了晶界附近χ相的形成,导致χ相数量增加,尺寸增大,由颗粒状弥散分布转变为层片状沿晶界呈网状分布,大大削弱了基体的连续性,造成熔敷金属强度上升而塑性、韧性显著下降。

The mechanical properties of high strength pure austenite welding wire deposited metals with two different Mo contents were tested, the impact fracture morphologies and metallurgical structures were studied by SEM, and the structures and composi- tion of secondary phases were analyzed by TEM and XRD. The results showed that with the increasing of Mo content, the strength of deposited metal increased while the ductility and toughness decreased evidently; the main cause was a Mo-rich zone was formed near the grain boundaries because of the segregation of Mo ; when Mo increased, concentration degree increased ac- cordingly, which strongly promoted the formation of χ phase and increased the amount and size of χ phase ; moreover the distri- bution of χ phase changed from being dispersed to along the grain boundaries in network, which resulted in the increase of strength and the decrease of ductility and toughness.