Metallurgical Failure Analysis of the Fractured Ring of a Gland Seal: Hydrogen Embrittlement? Factography can be Ambiguous

A cracking incident of a 304 stainless steel elbow serving in the synthesis gas purification device occurred during running. In order to get an understanding of the failure mechanism, a failure analysis was performed on the cracked elbow in this paper. The chemical composition, mechanical properties of strength, toughness and hardness, hydrogen content were identified and determined. The metallographical structure was observed and analyzed by optical microscope (OM) and X-Ray Diffraction (XRD), while the fracture morphology was observed by scanning electron microscope (SEM). The results showed that the chemical composition of the cracked elbow meet the requirements for China standard, while comparing with GB/T 14976-2012 standards, the strength and elongation of the leaked elbow are higher and lower respectively, and the hardness of the leaked elbow was higher than quality certificate documents that of HB ⩽ 187. Large quantities of martensite and δ-ferrite were observed in elbow, which indicated that the elbow was not well solid solution heat treated required by specification (1050°C,30min). The fracture morphology presents typical brittle fracture. The hydrogen content of cracked elbow was significant higher than that of other 304 stainless steel elbow serving in the environment without hydrogen. It is acknowledged that martensite showed higher sensitivity of hydrogen embrittlement compared with austenite. Furthermore, the operating temperature of cracked elbow was in the range of high hydrogen embrittlement sensitivity. Depending on the metallographical structure, strength, service environment, hydrogen content and fracture morphology, it can be concluded that hydrogen induced delayed cracking was the dominant mechanism of the failure.

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Failure analysis of a titanium Coriolis mass flow meter: A case of hydrogen embrittlement

Engineering Failure Analysis ◽

10.1016/j.engfailanal.2020.104618 ◽

2020 ◽

Vol 115 ◽

pp. 104618

Author(s):

I.G.R. Santos ◽

G.S. Vacchi ◽

R. Silva ◽

C.L. Kugelmeier ◽

D.C.C. Magalhães ◽

...

Keyword(s):

Hydrogen Embrittlement ◽

Failure Analysis ◽

Mass Flow ◽

Flow Meter ◽

Coriolis Mass Flow Meter

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Failure Analysis on the Rivet

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.2539 ◽

2010 ◽

Vol 654-656 ◽

pp. 2539-2542

Author(s):

Hong Ya Yu ◽

De Chang Zeng ◽

Zhong Wu Liu

Keyword(s):

Hydrogen Embrittlement ◽

Failure Analysis ◽

Zinc Coating ◽

Metallographic Examination ◽

Zinc Plating ◽

Micro Cracks ◽

The Matrix ◽

Expansion Effect ◽

And Diffusion ◽

Diffusion Of Hydrogen

This paper presents a detailed failure analysis on a rivet, which broke into two parts from the joint place between head and shank under a load of seven tons during service, by the combination of optical microscopy, SEM and EDS. The metallographic examination shows some micro-inclusions in the sample and many micro-cracks along the grain boundaries. SEM and EDS results show that the surface of the rivet was plated with a zinc coating and it was eroded severely. The fracture surface exhibits the characteristic of quasi-cleavage fracture, indicating an intergranular brittle fracture mode. Some micro-pores were found on the facets of intergranular cracked grains. Most importantly, the Crow-toe Pattern, one of river patterns or hairline seams, which is a typical microstructure of hydrogen embrittlement, was observed on the fracture. Based on above analysis, it is concluded that the failure of the rivet is caused by the hydrogen embrittlement. The hydrogen, most likely, comes from the zinc plating process. Due to the aggregation and diffusion of hydrogen into the matrix, the brittle cracking happens in the regions with stress concentration because of the volume expansion effect under the external force.

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Failure Analysis With the Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100095662 ◽

1972 ◽

Vol 30 ◽

pp. 482-483

Author(s):

John R. Devaney

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Integrated Circuits ◽

Failure Analysis ◽

High Reliability ◽

Military Applications ◽

Small Structure ◽

Useful Life ◽

Insight Into ◽

Scanning Electron

Occasionally in history, an event may occur which has a profound influence on a technology. Such an event occurred when the scanning electron microscope became commercially available to industry in the mid 60's. Semiconductors were being increasingly used in high-reliability space and military applications both because of their small volume but, also, because of their inherent reliability. However, they did fail, both early in life and sometimes in middle or old age. Why they failed and how to prevent failure or prolong “useful life” was a worry which resulted in a blossoming of sophisticated failure analysis laboratories across the country. By 1966, the ability to build small structure integrated circuits was forging well ahead of techniques available to dissect and analyze these same failures. The arrival of the scanning electron microscope gave these analysts a new insight into failure mechanisms.

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Using the scanning electron microscope for failure analysis of high density magnetic media

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126755 ◽

1987 ◽

Vol 45 ◽

pp. 392-393

Author(s):

Evelyn R. Ackerman ◽

Gary D. Burnett

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

Failure Analysis ◽

High Density ◽

Magnetic Media ◽

Specific Data ◽

Retrieval Systems ◽

Operating Environments ◽

The Media ◽

Scanning Electron

Advancements in state of the art high density Head/Disk retrieval systems has increased the demand for sophisticated failure analysis methods. From 1968 to 1974 the emphasis was on the number of tracks per inch. (TPI) ranging from 100 to 400 as summarized in Table 1. This emphasis shifted with the increase in densities to include the number of bits per inch (BPI). A bit is formed by magnetizing the Fe203 particles of the media in one direction and allowing magnetic heads to recognize specific data patterns. From 1977 to 1986 the tracks per inch increased from 470 to 1400 corresponding to an increase from 6300 to 10,800 bits per inch respectively. Due to the reduction in the bit and track sizes, build and operating environments of systems have become critical factors in media reliability.Using the Ferrofluid pattern developing technique, the scanning electron microscope can be a valuable diagnostic tool in the examination of failure sites on disks.

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