The Bauschinger effect in low-carbon steel

The Bauschinger effect may occur during pipe production and expansion as well as during flattening segments cut from pipes and used for the manufacture of full-size flat specimens for mechanical testing. The research deals with the Bauschinger effect in low-carbon pipe steel with ferrite-pearlite and ferrite-bainite structures. The alternate loading is followed by low-temperature heating and influences steel strain aging thus changing the Bauschinger effect. To investigate the Bauschinger effect the samples were subjected to loading including tension and compression which were carried out in different sequences. After alternating loading deformation of samples was absent. It was established that not depending on the loading scheme the ferrite-bainite structure is more susceptible to the Bauschinger effect than the ferrite-pearlite structure. Alternating loading followed by low-temperature heating leads to strain aging of steel which is accompanied by the increase of yield strength. The Bauschinger effect after aging is comparable to the Bauschinger effect before aging. The hardening magnitude depends on the loading scheme before low-temperature heating. The tendency to strain aging according to the loading scheme “tension + compression” does not depend on the initial structure. Whereas, with a ferrite-bainite structure according to the loading scheme “compression + tension” the highest level of yield strength is achieved at strain aging. Alternating loading carried out after strain aging leads to a sharp decrease in the yield strength and the appearance of the Baushinger effect. The Baushinger effect does not depend on the loading scheme before provoking heating and is mainly manifested with the ferrite-bainite structure.