Zhang Mengxing, Wang Changjun, Ma Dangshen, Liu Yu, Wang Weijun, Liang Jianxiong, Fang Chao, Chu Weihan, Huang Chuanjun
Special Steel Research Institute, Central Iron and Steel Research Institute Co., Ltd., Beijing 100081, China.
Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
Materials (Basel). 2024 Sep 19;17(18):4597. doi: 10.3390/ma17184597.
A novel non-magnetic Fe-21Cr-15Ni-5Mn-2Mo austenitic stainless steel with high strength and plasticity has been developed. The microstructure and liquid helium temperature (4.2 K) tensile properties of the top and bottom samples of large-size forged flat steel after solution treatment at 1090 °C were investigated. The results showed that the average grain size of the bottom sample (48.0 ± 6.7 μm) was smaller than that of the top sample (58.8 ± 15.3 μm), and the MX precipitates and Z phases were distributed in the matrix of the samples. The 4.2 K strengths of the samples at the top and bottom were high, and large amounts of annealing twin boundaries played a certain role in strengthening. After cryogenic tensile testing, large amounts of deformation twins, stacking faults, and dislocations were generated inside the austenite grains of both samples, which helped the material to obtain higher plasticity and strength. The top and bottom samples possessed excellent synergies of strength and plasticity at 4.2 K, and the 4.2 K tensile properties of the top sample were as follows: ultimate tensile strength (UTS) of 1850 MPa, yield strength (YS) of 1363 MPa, and elongation (EL) of 26%. The tested steel is thus believed to meet the requirements of combined excellent strength and plasticity within a deep cryogenic environment, and it would be a promising material candidate for manufacturing superconducting coil cases to serve in new generation fusion engineering.
一种具有高强度和高塑性的新型非磁性Fe-21Cr-15Ni-5Mn-2Mo奥氏体不锈钢已被研制出来。研究了大尺寸锻造扁钢在1090℃固溶处理后顶部和底部样品的微观结构以及液氦温度（4.2K）下的拉伸性能。结果表明，底部样品的平均晶粒尺寸（48.0±6.7μm）小于顶部样品（58.8±15.3μm），并且MX析出相和Z相分布在样品基体中。顶部和底部样品在4.2K时的强度较高，大量退火孪晶界起到了一定的强化作用。经过低温拉伸试验后，两个样品的奥氏体晶粒内部均产生了大量变形孪晶、层错和位错，这有助于材料获得更高的塑性和强度。顶部和底部样品在4.2K时具有优异的强度和塑性协同效应，顶部样品在4.2K时的拉伸性能如下：抗拉强度（UTS）为1850MPa，屈服强度（YS）为1363MPa，伸长率（EL）为26%。因此，该试验钢被认为满足深低温环境下优异强度和塑性结合的要求，并且将是制造用于新一代聚变工程的超导线圈外壳的有前景的候选材料。
