ULCB熔敷金属组织与碳、氧含量对力学性能的影响

MICROSTRUCTURE OF ULCB DEPOSITED METAL AND EFFECT OF CARBON AND OXYGEN CONTENTS ON MECHANICAL PROPERTY

不同保护气氛下焊接得到的超低碳贝氏体(ULCB)熔敷金属的组织由贝氏体板条和少量针状铁索体组成,贝氏体主要在原始奥氏体晶界及先形成的贝氏体条侧面形核,形成相互交叉的分布形态.Ar+1.5%02保护熔敷金属性能最好;Ar+4%CO_2保护时由于焊缝增碳,组织中生成了碳化物,熔敷金属强度升高,韧性降低;Ar+4%O_2保护时由于组织中生成大量氧化物夹杂,韧性急剧降低.

The microstructures of ultra low carbon bainite （ULCB） deposited metal under gas metal arc welding （GMAW） with different shielding gas are mainly consisted of bainite plate and acicular ferrite. The initial bainite nucleated at austenite grain boundaries and subsequent bainite plates can form at the side of initial plates, which presented an intersected configuration. The experimental results indicated that the mechanical properties are obviously related to the composition of shielding gas. The properties of deposited metal with shielding gas of Ar＋1.5%O2 is the best, while the impact toughness is very low as using Ar＋4%CO2 and Ar＋4%O2 because more carbides and oxides formed which are known to be harmful to the toughness.