超高强度钻杆低温断裂性能及裂纹扩展特征研究

发布时间：2018-06-29 05:59

本文选题：安全工程 + 材料失效　；参考：《安全与环境学报》2017年01期

【摘要】：超高强度钻杆在冬季低温环境下容易发生脆性断裂事故,为了从断裂力学角度揭示其冷脆现象的本质,采用ZBC2302-D型示波冲击试验机,获得了不同温度下超高强度钢在冲击断裂过程中的力-位移曲线,并对比分析了冲击功、起裂功和裂纹扩展功之间的变化关系。采用国家标准GB 4161—2007中的计算公式,计算了冲击试样的裂纹扩展量Δa和阻抗应力强度因子K_R;同时,引入K_R阻力曲线,得到超高强度钻杆在不同温度下的剩余强度图。结果表明,当冲击试样开始出现裂纹时,随温度降低,钻杆的初始起裂应力有所增加,出现硬化现象。当钻杆出现一定长度的裂纹时,随温度降低,阻抗应力强度因子越来越小,而且降低速度越来越快,剩余强度也表现出相同的变化趋势。随温度降低,材料抵抗裂纹扩展的能力逐渐下降,表明钻杆在低温下更容易断裂。
[Abstract]:In order to reveal the nature of cold embrittlement phenomenon of ultra-high strength drill pipe under low temperature environment in winter, ZBC2302-D oscillographic impact testing machine is used to reveal the nature of cold brittleness phenomenon in order to reveal the nature of cold brittleness phenomenon from the point of view of fracture mechanics. The force-displacement curves of ultra-high strength steel at different temperatures during impact fracture are obtained, and the relationship among impact energy, crack initiation work and crack propagation work is compared and analyzed. The crack propagation 螖 a and impedance stress intensity factor (KRR) of the impact specimen are calculated by using the calculation formula of national standard GB4161-2007, and the residual strength diagram of ultra-high strength drill pipe at different temperatures is obtained by introducing the resistance curve of Kstack. The results show that the initial cracking stress of drill pipe increases and hardening occurs with the decrease of temperature when the crack begins to appear in the impact specimen. When a crack of a certain length appears in the drill pipe, the impedance stress intensity factor becomes smaller and faster with the decrease of temperature, and the residual strength also shows the same change trend. With the decrease of temperature, the resistance of the material to crack propagation decreases gradually, which indicates that the drill pipe is easier to fracture at low temperature.
【作者单位】：西南石油大学油气藏地质及开发工程国家重点实验室;中国石油天然气股份有限公司塔里木油田分公司;
【基金】：国家自然科学基金项目(51374177)
【分类号】：TE921.2

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