40Cr钢紧固螺栓断裂原因分析

某石化厂管道连接法兰用40Cr钢紧固螺栓在使用不到1a(年)后发生径向断裂。通过宏观分析、化学成分分析、光学显微镜和扫描电镜观察、硬度测试等方法对螺栓断裂原因进行了分析。结果表明:螺栓在较高应力水平下服役,在应力和氢的共同作用下发生了氢脆断裂;导致其氢脆断裂的主要原因是螺栓在酸洗磷皂化和磷化过程中引入了较多的氢。     

深冷处理对3Cr13组织和力学性能的影响

对经不同深冷处理后的3Cr13钢进行了显微组织观察和力学性能检测。试验结果表明,深冷处理可以不同程度地提高3Cr13钢的硬度;淬火后进行深冷处理＋180℃×8h回火处理后没有改善3Cr13钢的冲击韧性;深冷处理可明显提高3Cr13钢耐磨性,其中深冷处理6h后耐磨性提高最为显著,其磨损失重下降了40％。     

60Si2MnA钢片弹簧断裂失效分析

某60Si2MnA钢片弹簧在使用10h后出现批量断裂,对断裂片弹簧进行了化学成分分析、硬度测试、金相检验以及断口微观形貌观察,以查明其断裂原因。结果表明:片弹簧断裂是由于在酸洗、电镀过程中析氢反应的发生,使其产生氢脆现象;同时由于热处理工艺过程控制不当,造成组织异常,硬度高于技术要求,加快了其氢脆倾向,最终导致片弹簧在外应力作用下发生氢脆断裂。     

252kV GIS机构止动螺栓的断裂失效分析

某批次35Cr Mo合金钢252 k V气体绝缘金属封闭开关设备(GIS)机构电镀锌止动螺栓在合闸试验调节中发生断裂失效,通过化学成分分析、断口分析、硬度测试、氢脆评估试验、金相检验等方法对螺栓断裂原因进行了分析。结果表明:该止动螺栓断裂是由氢脆造成的,而止动螺栓发生氢脆断裂是由螺栓电镀锌后去氢工艺不当造成的。最后提出了预防螺栓氢脆断裂的改进措施。     

1018钢螺钉断裂失效分析

采用直读光谱仪、显微维氏硬度计、光学显微镜和扫描电镜等仪器设备分别对1018钢渗碳处理的M3×6十字头自攻螺钉的化学成分、硬度、显微组织和断口形貌进行了分析,查明了螺钉断裂原因。结果表明:螺钉断裂属典型的脆性断裂,与其渗碳层深度超标,心部硬度又接近标准范围上限有关;螺钉断口还具有一定的氢脆断裂特征,是由于高的硬度和超标的渗碳层深度增加了螺钉的氢脆敏感性。最后根据螺钉断裂原因提出了改进措施。     

某导弹位标器用弹簧垫圈失效分析

某型号导弹住标器用弹簧垫圈在现场装配时发生断裂,对断裂件进行了化学成分、硬度和宏、微观检验。结果表明．弹簧垫圈冶金质量符合要求;其断裂失效是镀锌后除氢不彻底．导致装配时发生氢脆断裂。提出了建议。     

普通碳素钢渗氮后的氢脆敏感性

为了研究渗氮处理对钢的氢脆敏感性的影响,对气体渗氮处理的普通碳素钢进行了拉伸试验,对其断口进行了扫描电镜观察和显微组织分析。结果表明:渗氮层发生了氢脆延迟断裂,未渗氮部位发生了韧性断裂;渗氮处理增加了钢的氢脆敏感性。     

3Cr2W8V钢压铸模具断裂分析

3Cr2W8V钢压铸模具在压铸了几件铝件后发生断裂失效,采用化学成分分析、宏观检验、金相检验和断口分析等方法,对3Cr2W8V钢压铸模具的断裂原因进行了分析。结果表明：模具材料在断裂处的显微组织不均匀,存在大颗粒状碳化物或集中分布的未溶碳化物是造成模具断裂的直接原因。     

天然气井钻杆悬挂器断裂分析

某油田天然气井的钻杆悬挂器（套筒）在使用过程中发生断裂失效事故,采用化学成分分析、金相检验、硬度测试、断口分析、微区成分分析等方法对断裂件进行了分析。结果表明：该1Cr13钢悬挂器淬火后未经高温回火,不符合调质热处理工艺的技术要求。基体中的淬火马氏体组织硬度过高,残余内应力大,沿晶界及亚晶界聚集分布的颗粒状未溶碳化物（Fe,Cr）23C6降低了钢的抗蚀性。该套筒内联上接头的螺纹部位薄壁存在周向拉应力,使用时在高压天然气作用下,筒壁沿圆周方向附加有横向拉应力。套筒内部环境为湿硫化氢的天然气介质,结果导致该悬挂器沿纵向产生应力腐蚀断裂。     

SWRCH15A钢螺钉断裂原因分析

某批SWRCH15A钢螺钉在装配使用一个星期后,有10件螺钉发生自然断裂。通过宏观检验、金相检验、硬度及渗碳层深度测试、断口分析的方法,分析了螺钉断裂的原因。结果表明:在该批螺钉的电镀锌过程中,溶液中存在H~+和H_2O分子,促使发生阴极反应析出的氢原子富集,诱发阴极氢脆型应力腐蚀,从而造成螺钉的延迟断裂。     

双头螺栓失效分析

与汽车电机装配在一起的双头螺栓在拧紧后不久便发生断裂。采用扫描电镜、化学分析、金相检验等方法对失效件进行了检测，同时又进行了氢脆试验验证。结果表明，螺栓在进行表面酸洗及电镀时，氢向金属内部扩散和富集，当氢浓度达到一定临界值后，促使氢致裂纹的产生和扩展。在外应力的作用下，即出现氢脆现象导致螺栓断裂。     

高强度钛合金螺栓断裂失效分析

规格为M4×30 mm高强度钛合金螺栓在正常预紧装配后自行断裂。采用金相检验、扫描电镜断口分析、二次离子质谱分析和螺栓的受力分析等方法对螺栓断裂的原因进行了分析。结果表明,螺栓断裂的性质为低应力脆性断裂,断裂机理为氢致延迟断裂,导致螺栓氢致延迟断裂的原因主要与该批棒材原始氢含量过高有关。     

Failure in a high pressure feeding line of an oil refinery due to hydrogen effect

This work describes failure analysis of a feeding pipeline of an oil refinery. For this analysis visual inspection, dye penetration, optical and electron microscopy, XRD, tensile tests, fracture toughness tests and stress calculations were used. Result of the investigations show that hydrogen embrittlement has played an important role in the failure of the pipeline. For completing the case, hydrogen embrittlement damage of the piping material made from commercial ASTM A105M low alloy manganese steel was studied by using baking and hydrogenation treatments. Baking treatment was carried out at 520 °C for 20 min followed by slow cooling while hydrogenation treatment was carried out in a solution of H₂SO₄ which contained As₂O₃ for 0–6 h under cathodic situation. Then change in the mechanical properties and fracture toughness of the steel after the treatments were measured by tensile and fracture toughness tests. In addition, fractography was carried out using a scanning electron microscope (SEM) and image analyzer. Results show that the baking treatment increased elongation to failure and fracture toughness significantly and reduced yield strength slightly compared to the failed condition of the pipe. Hydrogenation treatment decreased elongation to failure and fracture toughness of the material considerably and increased strength barely. Increase in the hydrogenation time reduced ductility of the steel further more. These results indicate that hydrogen through hydrogen embrittlement mechanism, made the pipe material brittle and susceptible to cracking. Embrittlement with the assistance of an emergency shutdown and stress concentration provides damage nucleation and finally developed brittle fracture.     

弹簧断裂原因分析

弹簧在弹栓试验时发生断裂。采用化学成分分析、金相检验和扫描电镜分析等手段,对断裂弹簧进行了分析。结果表明,弹簧在去氢时未严格按工艺要求执行,致使大量的氢残留并呈弥散分布形态,进而形成沿晶裂纹。在外力作用下,导致沿晶脆性断裂。     

Atom probe tomographic observation of hydrogen trapping at carbides/ferrite interfaces for a high strength steel

A three-dimensional atom probe (3DAP) technique has been used to characterize the hydrogen distribution on carbides for a high strength AISI 4140 steel. Direct evidence of H atoms trapped at the carbide/ferrite interfaces has been revealed by 3DAP mapping. Hydrogen is mainly trapped on carbide/ferrite interfaces along the grain boundaries. Slow strain rate tensile (SSRT) testing shows that the AISI 4140 steel is highly sensitive to hydrogen embrittlement. The corresponding fractographic morphologies of hydrogen charged specimen exhibit brittle fracture feature. Combined with these results, it is proposed that the hydrogen trapping sites present in the grain boundaries are responsible for the hydrogen-induced intergranular fracture of AISI 4140. The direct observation of hydrogen distribution contributes to a better understanding of the mechanism of hydrogen embrittlement.     

The Effect of Al and Fe on the Intergranular Embrittlement of Co3Ti Alloys by Hydrogen Transport from the External Surface

1. IntroductionThe limited room-temperature tensile ductilityof illtermetallic alloys tested in air is now knownto arise from the hydrogen embrittlement process,which involves the surface reaction of active elements in intermetallics with water vapor in air alldgeneration of atomic hydrogen, leading to hydrogellembrittlement[1-7]. The Co3Ti alloys doped witll Alor Fe are much less susceptible to environmental elnbrittlement, indicating that the elements Al and Fein Co3Ti alloys have some su…     

汽车零部件氢致断裂的分析及预防

对氢脆的机理、氢脆的断口形貌、氢脆的表观形式、影响氢脆的因素、氢脆的预防以及氢脆的检查分别进行了介绍,并通过对汽车生产中典型氢致断裂案例的分析和研究,对氢脆断口形貌提出了判定依据:脆性断口、沿晶断裂、显微气孔、二次裂纹、发线花纹。并依据氢脆发生的机理和主要影响因素,强调对于高强度零件及时有效地进行去氢处理的重要性。     

Hydrogen and temper embrittlement in 9Cr–1Mo steel

Abstract

The synergism between hydrogen embrittlement and temper embrittlement has been investigated in a 9Cr–1Mo martensitic steel. Measurements of tensile ductility were used to monitor the development of embrittlement with increasing hydrogen content in material as tempered and aged for up to 5000 h at 500 or 550°C. A detailed examination was made of associated changes in fracture mechanism, precipitate microstructure, and interfacial and precipitate chemistry. A strong interaction between hydrogen and temper embrittlement was observed. Both types of embrittlement in isolation reduced tensile ductility by promoting a ductile interlath fracture mechanism: ‘chisel fracture’. Hydrogen and temper embrittlement acted synergistically to reduce ductility further by the promotion of brittle intergranular fracture and transgranular cleavage. The dominant factor controlling the interaction was the precipitation of a brittle intermetallic Laves phase containing phosphorus in solution. Phosphorus segregated to interfaces was considered to make an important, but secondary, contribution to the embrittlement observed.

MST/791     

30MnSi管桩钢筋延迟脆断原因分析

针对30MnSi管桩钢筋（PC钢棒）延迟脆断的现象,从力学性能、化学成分、显微组织、表面质量、断口形貌以及后续热处理工艺等方面对延迟脆断的原因进行了分析。结果表明：该管桩钢筋发生延迟脆断主要是由于其热处理过程中回火温度不稳定,使钢筋表面局部形成异常马氏体组织,这种组织形式自身存在着组织应力,而内氢的存在增加了管桩钢筋的内应力;当受外力作用时,外力和管桩钢筋自身的内应力经过一段时间逐渐集中于表面马氏体区,形成断裂源,从而导致管桩钢筋静置数日后突然脆断。