Stresses In Steel Components Research Articles

Evaluation of stress-loaded ferromagnetic structures using the magnetic recording method and extended signal analysis

This paper presents a new method of analysis of results obtained using the Magnetic Recording Method (MRM), which was applied to inspect tensile stress-loaded ferromagnetic samples. The MRM method comprised a two-step procedure. In the first step, a strictly defined magnetic pattern is recorded on the samples using an array of permanent magnets, and then the original residual magnetization is measured. Next, the samples are subjected to static stress. In the second step, the residual magnetization measurement is repeated. Comparative analysis of the measurement results allows for an accurate and unambiguous assessment of applied stress in steel components. Moreover, the magnetization was measured again after three years to investigate the effect of time on magnetization patterns. The study confirms that the method is stable and has a negligible time dependence.

Nondestructive Determination of Stresses in Steel Components by Eddy Current Method

Nondestructive Determination of Stresses in Steel Components by Eddy Current Method

Residual Stress Gradients in AISI 9254 Steel Springs Submitted to Shot Peening and Heat Treatment for Increased Fatigue Resistance

The presence of surface and subsurface residual stresses in steel components has a significant influence on fatigue resistance. In the present work, surface modification of AISI 9254 steel coil springs by heat treatment and multiple shot-peening procedures was investigated. Samples were characterized in the as-coiled, quenched, quenched and tempered, as well as submitted to single and double shot peening treatments. Depth resolved residual stress profiles were determined by X-ray diffraction combined with electrolytic dissolution of the steel. Fracture analysis was performed subsequent to fatigue tests by scanning electron microscopy. It was possible to show that double shot peening led to an increase in compressive stresses in the immediate sub-surface region, which improved fatigue resistance relative to the other tested conditions.

Residual and Applied Stress Estimation From Directional Magnetic Permeability Measurements With MWM Sensors

Conformable eddy current sensors with grid methods can provide an effective means for applied stress measurements and for characterization of residual stresses in steel components. This paper describes conformable MWM® (meandering winding magnetometer) sensors and high-resolution scanning MWM-Arrays for directional magnetic permeability measurements over a wide range of frequencies with grid methods. MWMs and MWM-Arrays are used for fatigue monitoring, crack detection, characterization of process-affected layers, including coatings, detection of surface-connected and hidden degradation, and damage characterization, e.g., detection and imaging of grinding burns. Tests have shown that these sensors can also provide the capability for residual/applied stress measurements in ferromagnetic materials, e.g., in steels. Specific examples described here illustrate this capability to estimate stresses in steels and other ferromagnetic materials from MWM measured permeability. Results of directional MWM permeability measurements, including permeability mapping, are presented here for (a) a 4340 steel specimen subjected to a series of tensile load tests with an incrementally increasing maximum load, (b) a broken 4340 tensile test specimen, (c) a shot-peened 300M steel specimen subjected to bending load tests, and (d) a shot-peened and subsequently ground high-strength steel component. Quick and inexpensive stress measurements at a point or, in a scanning mode, over a selected area are now becoming possible without permanently mounting sensors, albeit MWM sensors can be readily mounted, if needed, as well.