摘要
目的 对某S135钢级钻杆的腐蚀孔洞形成原因进行分析。方法 本文通过化学成分分析、金相组织分析、钻杆宏观外貌分析、力学性能测试、以及扫描电镜与能谱分析等一系列分析试验,对该S135钻杆材料的力学性能、化学成分、金相组织、非金属夹杂物、晶粒度等项目进行分析、对钻杆的外圆面宏观形貌进行分析,对钻杆的腐蚀孔洞特征和腐蚀产物进行分析。结果 该S135钢级钻杆的化学成分合格,符合产品技术条件要求;钻杆的强度、塑性、冲击韧性等力学性能指标均合格,均符合产品技术条件要求,其中冲击韧性值达到97J,超出技术条件要求值一倍以上;钻杆的金相组织为回火索氏体,为正常的调质热处理组织;钻杆的晶粒度级别为7级,符合产品技术条件要求;钻杆的各类非金属夹杂物级别均未超过1.0级,符合产品技术条件要求,钻杆外圆面存在大量的麻点、麻坑,腐蚀孔洞壁存在含氧元素的腐蚀产物,即存在氧腐蚀。结论,该S135钢级钻杆本体孔洞为应力腐蚀疲劳所致的孔洞。其产生因素有三:第一,钻杆本体外圆面上存在麻点、麻坑;第二,钻杆承受有交变弯曲应力;第三,钻杆外圆面局部氧腐蚀作用。
Abstract
Objective Analysis the S135 drill pipe’s corrosion holes Methods. In this paper, the chemical composition analysis, macroetching, metallographic test, mechanics performance testing, and scanning electron microscopy(SEM) analysis of the S135 drill pipe material,include mechanical property 、chemical composition 、metallurgical structure 、non-metallic inclusion 、and grain size ,and drill pipe’s top circle surface,and corrosion holes’s characteristics and corrosion products were analyzed. Results The drill pipe’s chemical composition、. mechanical property、metallurgical structure、grain size and non-metallic inclusion are qualified. Conclusion The analysis results show that the hole of the S135 drill pipe is caused by the stress corrosion fatigue. Its three factors: first, outer circumference surface of the existing pits,pockmarks; second, drill pipe under alternating bending stress; third, the pipe round face local oxygen corrosion.
关键词
S135钻杆;腐蚀性孔洞;麻点;氧腐蚀;交变弯曲应力;应力腐蚀
Key words
S135 drill pipe;corrosion holes;Pit;Oxygen corrosion; alternating bending stress; stress corrosion
王长健.
S135钻杆腐蚀孔洞形成原因分析[J]. 表面技术. 2016, 45(3): 58-63
WANG Chang-jian.
Analysis of corrosion holes for S135 drill pipe[J]. Surface Technology. 2016, 45(3): 58-63
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