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本文研究了GT35钢结硬质合金在不同热处理状态下获得的显微组织,测定了断裂韧性K_(IC)值,分析了K(IC)试样的断口形貌,并观察了断裂全过程。结果表明,在载荷作用下,GT35的断裂全过程由大Tic粒子首先解理断裂,随应变增大,较小Tic粒子参与断裂,已开裂TiC拉子中解理裂纹粗化及裂纹扩展直至断裂等阶段组成。裂纹扩展途径则随着钢粘姑相的组织结构和两相界面状况的不同而异,裂纹或者是沿两相界面曲折前进,或者撕裂前方粘结相而扩展。后者的进行是显微孔洞的成核聚合过程,脆性第二相及碳化物柱子是显微孔洞的核心,断裂过程受显微孔洞成核所控制。根据这种机制导出了裂纹穿越钢粘结相的定量关系式:解释了性能的变化。文章还指出,适当细化TiC粒子,强化硬质相以及高温奥氏体化加热淬火并回火能得到高的强韧性。
In this paper, the microstructure of GT35 steel bonded carbide under different heat treatment conditions was studied. The K_ (IC) value of fracture toughness was measured. The fracture morphology of K (IC) specimen was analyzed and the whole fracture process was observed. The results show that under the action of loading, the fracture of GT35 first clears the fracture by the large Tic particles. With the increase of strain, the smaller Tic particles participate in the fracture, and the cleavage of cracked TiC in the cracked TiC clapper and the crack propagation up to the fracture Other stages. The crack propagation path will vary with the microstructure and the interphase of the two phases. The crack propagates either along the two-phase interface, or by tearing the front bonding phase. The latter is the process of micropore nucleation and polymerization. The brittle second phase and the carbide column are the core of the micropore. The fracture process is controlled by the micropore nucleation. According to this mechanism, the quantitative relationship of crack through steel bonding phase is derived: The change of performance is explained. The article also pointed out that appropriate refinement of TiC particles, strengthening the hard phase and high temperature austenitizing heating quenching and tempering can get high strength and toughness.