电渣堆焊高铬铸铁界面温度场及组织性能

用电渣堆焊的方法在D32低合金钢表面堆焊高铬铸铁硬面层，测量了堆焊过程中热影响区的温度场，研究了热影响区、复合界面及硬面层的微观组织和力学性能.结果表明，电渣堆焊加热和冷却速度较慢，稳定阶段时低合金钢基材温度分布均匀，在堆焊方向最大温度梯度为-21.25℃/mm；低合金钢基板内最大热应力为53.4 MPa，低于低合金钢的抗拉强度，有效避免了裂纹的产生；复合界面平整清晰，存在宽度约50μm的奥氏体带状区；热影响区晶粒有所长大，为铁素体加珠光体组织；高铬铸铁硬面层由奥氏体、碳化物和少量马氏体组成，M₇C₃型碳化物细小且均匀分布于奥氏体晶界；复合界面结合强度为96 MPa；试样熔合区的冲击吸收能量(53 J)较硬面层冲击吸收能量(10.7 J)明显提高；亚共晶高铬铸铁硬面层在较大磨损载荷下发生马氏体相变，硬度提高，耐磨粒磨损性能优良.

Study on temperature field,microstructure and properties of electroslag surfacing high chromium cast iron

In this paper, the high chromium cast iron (HCCI) hardfacing layer is deposited on the surface of D32 low-alloy steel by electroslag surfacing method. Combined with the temperature field measurement of the heat-affected zone (HAZ) during the surfacing process, the microstructure and mechanical properties of the HAZ, composite interface and hardfacing layer are studied. The results show that: the heating and cooling rates are slower during the electroslag surfacing, and the temperature distribution in the low alloy steel substrate during the stabilizing stage is uniform; the maximum temperature gradient in the surfacing direction is 23.1 ℃/mm. The maximum thermal stress in the low-alloy steel substrate is 25.9 MPa, lower than its tensile strength, which effectively avoids the occurrence of cracks; the composite interface is smooth and clear, with an austenite band region, about 50 μm in width; The grains of HAZ have grown, whose microstructure is a mixture of ferrite and pearlite. The microstructure of HCCI hardfacing layer is composed of austenite, carbides and a small amount of martensite. The M₇C₃ type carbides are small and uniformly distributed in austenite grain boundaries. The bonding strength of the composite interface is 96 MPa; the impact energy (53 J) of the composite sample is significantly higher than that of the HCCI hardfacing layer (10.7 J). During abrasion, the HCCI hardfacing layer undergoes martensitic transformation under a large load, the hardness is improved, and an excellent performance in wear resistance was obtained.