Mechanical properties of cold-formed thick-walled steels at elevated temperatures
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To study the mechanical properties of cold-formed thick-walled steels (with a thickness greater than 3mm) at elevated temperatures and the effect of cold-work forming on high-temperature performance of steels, this paper presents a series of specially designed material tests on Q345 steels. The coupons were pretreated by strengthening original plates to different strain levels and aging process. A total of 56 coupon tests were carried out using steady state test method for temperatures ranged from 20 to 600°C. Based on the tests, mechanical properties including yield strengths, ultimate strengths, elasticity modulus and stress-strain curves were obtained. Then, the influence of cold-work forming for steels at ambient and elevated temperatures were investigated by comparing failure modes, constitutive relationships and retention factors of steels with different strengthening degrees. Further, for predicting the mechanical properties of cold-formed thick-walled steels at elevated temperatures, a set of revision coefficients for hot-rolled steels was proposed depending on the tests data. Finally, verification tests on specimens cut from the typical cold-formed thick-walled steel tube have been conducted to validate the proposed prediction model.