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通过激光直接沉积成形技术制备不同Mo元素含量的Cr-Ni不锈钢,对工艺参数进行优化,并对Cr-Ni不锈钢合金进行成分设计与组织性能评价。采用半导体激光器直接沉积成形15Cr21Ni7双相不锈钢合金粉添加xMo(x=0%、1%、2%、3%、4%),在激光功率1 800 W,激光扫描速度5mm/s,搭接率30%,送粉率8.9g/min的优化工艺参数下获得了长宽高分别为10mm×10mm×4mm的不锈钢块体样品。利用光学显微镜、电子探针、X射线衍射仪、显微硬度计及电化学测试系统进行了沉积层的显微组织、成分、物相及显微硬度、耐蚀性分析。实验结果表明,沉积层无气孔和裂纹等缺陷,成形性良好;沉积层的中部稳定,显微组织主要由岛状枝晶、奥氏体枝晶和枝晶间区域为铁素体、奥氏体、合金碳化物的混合组织组成;随Mo含量的增加,沉积层的耐蚀性随Mo含量的增加先升高后降低,当Mo含量达到3%时,耐蚀性获得最高值:自腐蚀电流密度为167.21nA/cm~2,自腐蚀电位为-142.26 mV。沉积层的显微硬度随Mo含量的增加变化不大,其平均显微硬度在340~390HV。
The Cr-Ni stainless steel with different Mo content was prepared by laser direct deposition forming technology, the process parameters were optimized, and the compositional design and microstructure and properties of the Cr-Ni stainless steel alloy were evaluated. Direct depositing 15Cr21Ni7 duplex stainless steel alloy powder with semiconductor laser and adding xMo (x = 0%, 1%, 2%, 3%, 4%) at a laser power of 1 800 W and a laser scanning speed of 5 mm / 30%, feeding rate of 8.9g / min under the optimized process parameters obtained length and breadth of 10mm × 10mm × 4mm stainless steel block samples. The microstructure, composition, phase, microhardness and corrosion resistance of the deposited layer were analyzed by optical microscope, electron probe, X-ray diffraction, microhardness tester and electrochemical test system. The experimental results show that the deposited layer has no defects such as pores and cracks and the formability is good. The middle part of the deposited layer is stable. The microstructure is mainly composed of island dendrites, austenite dendrites and dendrites with ferrite and austenite , And alloy carbide. With the increase of Mo content, the corrosion resistance of the deposited layer first increases and then decreases with the increase of Mo content. When the content of Mo reaches 3%, the corrosion resistance reaches the highest value: the self-corrosion current The density is 167.21nA / cm ~ 2 and the self-corrosion potential is -142.26 mV. The microhardness of the deposited layer does not change much with the increase of Mo content, and its average microhardness is in the range of 340 ~ 390HV.