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借助热力学计算软件(Thermo-Calc)、光学显微镜(OM)、扫描电子显微镜(SEM)以及电子布氏硬度计(HBE-3000A)分别研究了1140℃固溶处理下保温不同时间对自行研制的低镍耐热铸钢组织和性能的影响。Thermo-Calc计算结果表明,降低Ni后的新钢种高温组织为奥氏体和铁素体双相组织;通过金相观察并辅助于Image Pro Plus统计软件表明,随着保温时间增加,双相组织中铁素体含量逐渐增多,且两相中存在富Cr区,并随保温时间增长,Cr-rich先在两相相界处(靠近奥氏体)聚集随后消失;当铁素体中的Mo含量达到0.40%(质量分数),基体中开始析出短杆状MC型碳化物(MoC);当试样在1140℃下保温40 min时,由于铁素体含量明显增加,分布更加均匀,且析出相的种类也由Nb_6C_5+M_(23)C_6增加为Nb_6C_5+M_(23)C_6+Mo C,其布氏硬度达到最高值。
The effects of heat-holding at 1140 ℃ for different time on the self-developed low-temperature were studied by Thermo-Calc, OM, SEM and HBE-3000A. Effect of Nickel Heat Resistant Cast Steel on Microstructure and Properties. The results of Thermo-Calc calculation show that the high-temperature microstructure of the new steel after the reduction of Ni is austenite and ferrite dual-phase microstructure. By metallographic observation and assisted by Image Pro Plus statistical software, it shows that with the increase of holding time, The ferrite content gradually increases in the microstructure, and the Cr-rich region exists in the two phases. With the increase of holding time, Cr-rich firstly aggregates and disappears in the two-phase boundary (near austenite). When the content of Mo (Mass fraction), the short rod-shaped MC carbide (MoC) began to precipitate in the matrix. When the sample was incubated at 1140 ℃ for 40 min, the content of ferrite increased and the distribution was more uniform and precipitated The types of phases also increased from Nb_6C_5 + M_ (23) C_6 to Nb_6C_5 + M_ (23) C_6 + MoC, and their Brinell hardness reached the highest value.