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采用焊条电弧堆焊方法对45钢进行了三层堆焊试验,并进行了不同温度的焊后回火处理,研究了熔敷金属的显微组织和硬度分布。结果表明:回火温度为400℃时,熔敷金属显微组织是残余奥氏体和粒状贝氏体,550℃时出现了回火马氏体,700℃时出现了魏氏组织。回火温度为550℃时,熔敷金属的显微硬度值最大,400℃次之,700℃最小。这是由于回火温度为550℃时熔敷金属中形成了特殊碳化物,造成了二次硬化现象;回火温度为700℃时魏氏组织的出现大大降低了熔敷金属的力学性能,且熔敷金属中的马氏体分解加剧,特殊碳化物会迅速地聚集长大,严重地削弱了弥散强化的效果。
The three-layer welding test of 45 steel was carried out by arc welding of electrode, and the post-welding tempering of different temperature was carried out. The microstructure and hardness distribution of the deposited metal were studied. The results show that when the tempering temperature is 400 ℃, the microstructure of the deposited metal is retained austenite and granular bainite. Tempered martensite appears at 550 ℃, and Widmanstatten microstructure appears at 700 ℃. When the tempering temperature is 550 ℃, the microhardness of the deposited metal is the largest, followed by 400 ℃ and 700 ℃. This is due to the formation of a special carbide in the deposited metal at a tempering temperature of 550 ° C, resulting in secondary hardening; the appearance of Widmanstalling at a tempering temperature of 700 ° C significantly reduces the mechanical properties of the deposited metal, and Deposition of the martensite in the metal intensifies, special carbide will rapidly gather to grow seriously weakened the dispersion strengthening effect.