管线钢热轧卷板屈服强度的试验研究

为了准确测定管线钢热轧卷板的屈服强度，以X90管线钢热轧卷板为例，采用规定比例极限σP50的计算方法，通过横向、30°和45°方向圆棒试样和直接拉伸矩形试样的拉伸试验、规定比例极限σP50的试验、横向矩形试样预拉伸至规定比例极限σP50的试验等，测定了屈服强度RP0.2和Rt0.5的变化情况。结果表明，预拉伸至σP50对试样力学性能的影响不大；30°和45°方向的矩形拉伸试样σP50的误差限分别为±20 MPa、±5 MPa，在此范围内的屈服强度RP0.2和Rt0.5数据分散性较小，略高于相同方向的圆棒试样，与横向矩形试样的屈服强度略高于横向圆棒试样的规律性一致。预拉伸至规定比例极限σP50能够准确计算管线钢卷板的屈服强度。

Experimental Study on Yield Strength of Pipelines Steel Hot-rolled Coil

In order to accurately detect the yield strength of pipeline steel hot-rolled coil, taking X90 pipeline steel hot-rolled coil as an example, adopting specific proportional limit σP50 calculation method to detect yield strength RP0.2 and Rt0.5 changes through tests, including round bar specimen in transverse direction, 30° , 45° direction, direct tensile test of rectangular specimen, specific proportional limitσP50 test, the prestretching of transverse rectangular sample to specific proportional limitσP50 and so on. The results indicated that the prestretching to σP50 slightly affect the mechanical performance. The σP50 error limits of rectangular tensile specimens in 30°, 45° direction were ±20 MPa, ±5 MPa, the data dispersion of yield strength RP0.2, Rt0.5 within this range are smaller, slightly higher than the round bar specimen in the same direction, with the same regularity as transverse rectangular specimens and transverse round specimens. Pre-tension to specific proportional limitσP50 method can accurately calculate the yield strength of pipeline steel hot-rolled coil.