20CrNi4Mo螺栓用钢的高温持久性能

High temperature endurance of a new type bolt steel 20CrNi4Mo

研究了新型螺栓用20Cr Ni4Mo钢的高温持久性能,在高温持久试验机上测定了该种螺栓用钢在350~450℃不同应力条件下的高温持久强度。用国际上普遍采用的等温线法、时间-温度参数法对试验数据进行拟合,得到了回归方程,并进行了外推估算。比对各种方法的拟合以及外推情况结果表明,拉森-密勒（L-M）参数法拟合及外推效果最好,因此,L-M参数法最适合于本文研究材料持久性能的预测。用L-M参数法外推20Cr Ni4Mo钢在工况温度为230℃、持久105h时的强度极限σ230105=186.21 MPa,表明该螺栓用钢在此工况温度下应具有较好的持久性能。

High temperature endurance of a new type holt steel 20CrNi4Mo was investigated. The creep rupture strength in 350-450 ℃ under different stresses was measured by use of high temperature endurance testing machine, the experimental data were fitted through some international commonly used methods such as the isotherm method and the time-temperature parameter method, and the regression equations were obtained and extrapolation estimation was carried out. Comparison of the fitted and extrapolated results, it is shown that the Larson Miller （L-M） parameter method can get a preferable fitting and extrapolation effect, and it is suitable to predict durable performance of the 20CrNi4Mo bolt steel. Further extrapolation resuh show that the creep rupture strength of the 20CrNi4Mo bolt steel at 230 ℃ for lasting 105 h is 186.21 MPa, which shows the steel should have a good rupture performance at working temperature of 230 ℃.