Residual Stress Evolution in Low-Alloyed Steel at Three Different Length Scales

Abstract

Quantitative and qualitative residual stress evolution in low-alloyed steel during heat treatment is investigated on three different length scales for sourgas resistant seamless steel tubes: on the component level, on the level of interdendritic segregation and on precipitate scale. The macroscopic temperature, phase and stress evolution on the component scale result from a continuum model of the heat treatment process. The strain and temperature evolution is transferred to a mesoscopic submodel, which resolves the locally varying chemistry being a result of interdendritic segregation. Within the segregation area and the surrounding matrix precipitates form. They are categorized with respect to their tendency for formation of microscopic residual stresses. After rapid cooling macroscopic stresses up to 700 MPa may form dependent on the cooling procedure. Mesoscopic stresses up to Δ50 MPa form depending on the extent of segregation. Carbides and inclusions occuring in low-alloyed steel are ranked by their tendency for residual stress formation in the iron matrix. This scale bridging study gives an overview of residual stresses, their magnitude and evolution on three different length scales in low-alloyed steels and the results presented can serve as a input for steel design.

Study of the Mechanical Properties and Microstructure of Spiral Tubes and Actuators for Controlled Extension Fabricated with Beryllium Bronze Strips

“…Upon the measurements and analysis of driving force, pointing accuracy, bending stiffness, and verification via the residual stress measurement, we could conclude that the STACERs stabilized under 320 • C and for 2 h exhibited superior performances; from the view of the study of the material, most of the macro properties should be elucidated from microstructure evolution [37][38][39][40][41]. For this reason, we conducted electron backscatter diffraction (EBSD) measurements and transmission electron microscopy (TEM) tests for the as-received raw strips and developed a STACER stabilized under 320 • C + 2 h for more explanation on the micro level.…”