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Materials and the Sources of Stresses
Published in Neville W. Sachs, Practical Plant Failure Analysis, 2019
Low Alloy Steels − Steels that have the ability to be made stronger and tougher because they have good response to heat treating. 4140, 4142, 4147, 4150 − Direct hardening low alloy steels with chrome and molybdenum4340 − Nickel−chrome−molybdenum direct hardening steel used where exceptional strength and toughness is needed.4617, 4620 − Nickel−molybdenum direct hardening steel6120, 6150 − Chrome−vanadium steels8617, 8620 − Nickel−chrome-molybdenum steels used for surface (case) hardening52100 – High carbon bearing quality steel with chrome additive
Power Connectors
Published in Paul G. Slade, Electrical Contacts, 2017
Disc-spring washers are generally made of spring steel such as high-carbon, chrome-vanadium, chrome-vanadium-molybdenum, tungsten-chrome-vanadium and stainless steels. However, other resilient materials, such as silicon and phosphor bronze, beryllium copper, inconel and nimonic can also be employed. Effect of different mechanical contact devices on the contact resistance of a bolted joint under current-cycling conditions is illustrated in Figure 5.77. Figure 5.78 shows joint configurations for jointing aluminum or copper busbar conductors. In all cases, it is recommended to use flat washers at least 3–4 mm thick. With steel bolts, disc spring washers with a high spring constant and flat washers with thickness at least twice that of the disc-spring washer should be applied.
The reciprocating piston petrol engine
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
In conventional practice, the valve springs consist of wire wound in the form of a helix or coil. The valve closing load is conveyed axially along the spring, which stresses the material principally in torsion. For the valve open and the valve closed conditions, the ratio of spring loads is usually in the region of 2:1. Since the valve spring is compressed between parallel abutments, its end coils are ground flat and square with the spring axis. The coil ends are also diametrically opposed, so as to minimize an inherent tendency towards bowing of the spring as it is being compressed. Because they are subjected to severe service, valve springs are produced from high-duty materials, these generally being either hard-drawn carbon steel or chrome-vanadium steel. To reduce stress concentration in the spring wire and thus make it less liable to fail by fatigue, the valve spring may be shot peened. In this process the wire surface is bombarded at high velocity with metal shot, which induces a residual compressive stress that discourages crack propagation in the material.
Improvement of production process variations of bolster spring of a train bogie manufacturing industry: a six-sigma approach
Published in Cogent Engineering, 2023
Ilesanmi Daniyan, Adefemi Adeodu, Khumbulani Mpofu, Rendani Maladzhi, Grace Mukondeleli Kanakana-Katumba
Train bogies are classified based on the structure of the suspension gear, which are of two types, namely: swing hanger type and the small lateral stiffness bolster springs type. The focus of this study is the production of the bolster helical compression spring. This springs are found in the secondary suspension system of the main line bogie. They are made up of chrome vanadium or chrome molybdenum steel. The study identified problem of variations in the diameter and free height of the bolster compression springs produced during a specific period. The problem was identified via Voice of Customer basis (VOC). Customers interviewed complain of wastage of materials due to the defects, which have serious negative financial, implication of the organization if not properly managed. The customers also complained about variation in the manufacturing lead-time, which is an indication of the presence of wastes due to the existence of non-value activities.