采用激光增材制造技术制备了12CrNi2合金钢,其主要由铁素体基体和少量残余奥氏体组成,沉积层间热影响区边界明显,与沉积层内部组织相比,其内铁素体粗化而奥氏体减少。经过等温淬火热处理后,沉积态合金钢组织不均匀性消除,同时,强度亦得到明显提高。还报道了贝氏体组织形貌特征随等温淬火温度与时间变化的演化规律及其对成形合金钢屈服/抗拉强度与延伸率的影响机制,提出了获得综合力学性能最优的热处理条件。

A 12CrNi2 alloy steel, which was composed of a major ferrite and minor austenite, has been fabricated by means of the laser additive manufacturing technology. The microstructure of distinct interlayer heat-affected zone consists of coarse ferrite and a small amount of austenite comparing to the microstructure of inner deposited layer. The microstructure of as-deposited steel was homogenized after isothermal quenching treatment, and meanwhile the strength was improved significantly. The evolution process of the microstructure and morphology of the bainite with the isothermal quenching temperature and time and its effect on the yield strength and tensile strength as well as the elongation of the alloy steel are reported. And the optimized heat treatment process with good comprehensive mechanical properties is proposed.