Steel mechanical loading effect

Some practical cases are determination of residual stress in steel springs, the effect of mechanical loading on stress relaxation of machined and shot-peened nickel-base alloys,65 determination of residual stress level in turbine engine disks as they accumulate engine cycles,65 66 effect of manufacturing processes on residual stress, measurement of stress gradients in mechanical, electronic and structural components, effect of heat treatment on residual stress in steel coil springs, effect of variable heat treatment temperature on residual stress in iron alloys, measurement of stress in multiphase materials and composites and stress measurements at locations of stress concentrations. 

In a second example, CF is promoted by increased impurity-sulfur in ferritic steels subjected to low-frequency loading in pressurized pure water at 288°C (Fig. 15) [22,23], MnS inclusions, which intersect crack flank surfaces, dissolve to enrich the occluded crack solution in sulfide. These anions promote crack advance by increasing the anodic charge that is passed per film rupture event, or perhaps by the HEE mechanism. This effect of steel sulfur content is severe for a stagnant environment within the autoclave, and is eliminated by turbulent solution flow which reduces sulfide buildup within the crack [66],... 

Silicon is a well-known single crystalline semiconductor material, which is widely used in integrated circuits (ICs). Silicon possesses excellent mechanical properties, which surpass stainless steel in yield strength and hardness with good mechanical stability. Silicon also has a high piezoresistance effect, whose resistivity changes when mechanical loads or stresses are applied to it. This makes silicon... 

However, other approaches have also successfully been adopted. For example, Dickie and Ward [53] have studied single-lap joints exposed to a high humidity at moderately elevated temperatures but maintained a constant stress on the joints. Also, periodically the joints were removed from the high-humidity environment and exposed to a salt solution for a short time period. Using this accelerated-ageing test they were able to rank the durability performance of various adhesive systems in a comparatively short timescale. Further, they reported that not only were the kinetics of mechanisms of environmental attack accelerated, but also the exact details of the mechanisms were affected by the levels of the applied load. For example, for joints which consisted of bonded galvanised steel substrates, the effect of relatively high applied loads was to prevent the formation of an effective barrier of corrosion products, i.e. passivation of the substrate surface was prevented. This allowed the electrochemical corrosion process to proceed unimpeded, and hence at a faster rate than for similar, but unstressed, joints. Thus,... 

In order to make ILs a more effective lubricant for steel/aluminum friction pair especially at higher loads to reduce corrosion and wear Al matrix, a series of phosphate ester functional group-containing ILs was designed and synthesized. Mu et al. [84-86] synthesized a new series of imidazohum cation-based ILs with 0,0-diethylphosphonyl groups on the alkyl side chain (Fig. 9.12), evaluated the tribological properties of the ILs, and discussed possible mechanisms of action. 

The usual approach is to use a tensile" or universal testing machine that is equipped with a compression load cell. The compression takes place between parallel steel plates, which may incorporate a self-alignment mechanism. Rather than a universal machine, an apparatus working in compression only is equally satisfactory if the volume of work justifies a dedicated apparatus. An alternative is to use a compression cage in a tensile machine effectively to reverse the motion of the machine. However, these are now seldom seen, as they can introduce considerable friction errors, and there is always difficulty in alignment. As will be appreciated, for stiff materials the forces and hence machine capacity required can be large. 

---