The effect of overloads on threshold and crack closure

Overstrain effects during variable amplitude service history testing

High strength low alloy (HSLA) steels are a relatively new group of alloys having higher strength as a result of composition and processing variations. Because these HSLA steels are being widely used in applications susceptible to a few cycles of stress or strain in the plastic region, the low cycle fatigue (LCF) properties of these steels are very important to design engineers; and as a result, a knowledge of the extent of the effects of several steel variables (viz, thickness, composition, processing variables, and so forth) and cold-work on the LCF properties of a single steel grade is very desirable from design safety considerations. Specimens obtained from a commercial grade of hot-rolled, pickled and oiled Nb-bearing, fine grained HSLA steel covering three thicknesses, two heats and four coil-positions were characterized as regards to their monotonie and cyclic properties. The present study indicates that the LCF behavior of this commerical grade steel is very insensitive to “steel variables” such as composition, thickness and coil-position. The large increase in monotonie strength obtained by cold-work is not retained under cyclic loading and the LCF behavior of cold-worked samples approached that of undeformed material.

Steel variability effects on low cycle fatigue behavior of a single grade of high strength low alloy steel

Bond life degradation of steel strand and concrete under combined corrosion and fatigue

Effect of Periodic Large Strain Cycles on the Fatigue Behavior of Steels

Successful estimation of the service life of a structure or component which is subjected to a complex history of loading, depends on a suitable cumulative-damage summation technique. A general technique must be capable of predicting the effects on fatigue life of geometry, mean stress or strain, occasional overloads or overstrains, frequency of cycling and environment. As a contribution towards the general solution, this paper describes the utilization of a fatigue-damage summation method which incorporates two of these variables, mean stress and overloads. The method is tested for complex load histories in mild-steel specimens in the intermediate to long-life range.

P. Watson

Papers

Fatigue-damage evaluation for mild steel incorporating mean stress and overload effects

An Evaluation of the Fatigue Performance of Automotive Steels