Protective coating has no adverse effects on fastener life. Notched square-bar specimens are black-oxide coated and tested to failure to determine susceptibility to hydrogen embrittlement. Fastener manufacturers routinely apply a protective finish to bolts and screws that prevents rust and corrosion. However, there is some concern that plating processes can contribute to hydrogen contamination in fasteners, resulting in a potential for embrittlement. Materials undergo hydrogen embrittlement when atomic hydrogen is absorbed and diffused throughout the metal during electroplating or coating. Accepted theories of hydrogen behavior in high-strength materials stipulate that hydrogen is a mobile atom in the crystalline matrix of metals and will, over time, migrate to points of highest stress. This can eventually result in brittle failure. Generally, higher applied stress means shorter time to failure. And susceptibility to embrittlement tends to increase with the tensile strength or hardness of the steel. Thus, the very design of high-strength fasteners, with their many stress risers and notches and typical exposure to high dynamic loads, makes them ideal candidates for failure by hydrogen embrittlement. Hydrogen is an acknowledged by-product of many surface-treatment processes including black-oxide coating, and zinc and cadmium plating. Acid cleaning prior to plating is of major concern because it can generate hydrogen on the fastener surface. Plating can involve electrodeposition of protective materials, which can produce hydrogen. The processes also expose fasteners to various cleaning solutions and coatings, many of which have not been fully evaluated with respect to hydrogen contamination. One reason for a lack of information is that there has been a limited ability to measure hydrogen embrittlement. Recently, a method has been developed to measure the hydrogen-generating potential of coating and plating processes. This test gives a clean bill of health to fasteners with a black-oxide coating. Black oxiding is a dip process in which parts
Products & Services
Plating and Anodizing Equipment
Plating equipment and anodizing equipment is used to apply a finish to a products to increase its durability or to resist corrosion.
Plating Chemicals and Anodizing Chemicals
Plating chemical and anodizing chemicals include metal salts, formula additives, and other consumables for the electrodeposition, electroless plating, electroplating and anodized layer formation.
Washers are disks of metal or non-metallic material placed beneath a nut, an axle bearing, or a joint, to relieve friction, prevent leakage, isolate, prevent loosening, or distribute pressure.
Spring washers, sometimes called disc springs, lend their mechanical capabilities to the unique profile of the material: the irregularities of the washer compress with a proportionate resistance to return to their predeflected shape. Spring washers are employed in applications where assemblies need a part to take up play, maintain assembly tension, compensate for expansion or contraction in materials, or to absorb intermittent shock loads and provide a controlled reaction under dynamic loads.
A nickel, chromium, molybdenum and cobalt-based alloy with outstanding strength and corrosion resistance, MP35N is ideal for applications in the aerospace, defense, marine, chemical processing, oil...
Topics of Interest
T. HINO, K. YAMAGUCHI, T. JINUSHI, Y. HIROHATA AND Y. YAMAUCHI
Department of Nuclear Engineering, Hokkaido University, Kita-13, Nishi-8, Kita-ku, Sapporo-shi, 060-8628 Japan
Stress tests including large flow fluctuations and power outages demonstrate that a Palladium-diffuser designed for improved reliability was able to sustain "real-life" operating conditions without...
The separation or fragmentation of a solid body into two or more parts, under the action of stresses, is called fracture. The subject of fracture is vast and involves disciplines as...
Tantalum (Ta) shows excellent corrosion resistant. However, tantalum is susceptible to hydrogen embrittlement. This paper presents a failure analysis of tanalum thermometer sheath-tube used in...
JIMING CHEN  , YING XU  , SHAOYU QIU  , T. MUROGA  , YING DENG  , ZENGYU XU 
A V4Cr4Ti alloy (NIFS-Heat 2) has been studied on its hydrogen embrittlement behavior...