研究了一种低C、低Mn、高Cr和高Nb低合金钢经控轧控冷及轧后回火处理后性能与组织的变化，并对试验钢进行了抗氢致开裂(HIC)试验。结果表明：与轧态相比，回火处理后试验钢的力学性能有较大提高，600℃左右回火后屈服强度由轧态519MPa增加到626MPa，抗拉强度由653MPa增加到705MPa，且韧性基本未降低，回火处理后组织仍以针状铁素体为主，回火后M/A岛尺寸减少。此外，轧态与回火态钢均能满足抗HIC试验衡量标准，回火处理后抗HIC性能优异。降低Mn质量分数能显著提高低合金钢抗HIC性能，提高Cr质量分数和Nb质量分数能有效强化低Mn钢的强度。

The evolution of mechanical properties and microstructures of a low-alloy steel containing low C, low Mn, high Cr and high Nb were studied after thermo mechanical control process and tempering process after the rolling, respectively.Moreover, resist-hydrogen induced cracking (HIC) tests were carried out on the tested steels. The results show that the mechanical properties of tempered steels are improved comparing with of rolled steel. After tempered at 600℃ for 1h, its yield strength is increased 100MPa, and tensile strength is increased 50MPa, but the toughness almost has no reduction. The type of microstructures after tempering process is similar with of rolling condition, which is still mainly composed of acicular ferrite, and a small amount of quasi-polygonal ferrite. However, M/A constituent gradually reduces with the increasing of tempering temperature. The results of the HIC test indicate that all the tested steels can meet the requirements of standards, and the resist-HIC performance is improved after the tempering treatment.