Abstract: Regarding the requirement of residual ferrite content not exceeding 1% and grain size controlled within 4-6 levels in 316H austenitic stainless steel. Based on Thermo calc thermodynamic calculations and research on the changes in microstructure and properties during solid solution treatment， a progressive solid solution treatment method is proposed. The thermodynamic calculation results show that the solid solution temperature range for the formation of a single austenite structure in 316H steel is 975.5 ℃-1 281 ℃.Solid solution experimental research shows that the experimental steel treated with single stage solid solution can meet the requirements for residual ferrite content at 1 050 ℃ and 1 100 ℃， but the distribution of grain size is uneven and the phenomenon of mixed crystals is severe， leading to an increase in plasticity and toughness of the experimental steel， but the strength is obviously decreased. Adopting a progressive solid solution treatment of 1 000 ℃ （1 h）+1 100 ℃ （1 h）， while ensuring that the ferrite content and grain size meet the requirements， the uniformity of the structure is significantly improved， and the strength and toughness of the sample are higher than those of single stage solid solution treatment.

Key words: Austenitic Stainless Steel 316H, δ-ferrite, Grain Size, Progressive Solid Solution Treatment Method, Mechanical Properties of the Material

摘要： 针对316H奥氏体不锈钢中残余铁素体含量不高于1%与晶粒尺寸大小控制在4～6级的要求。基于Thermo-calc热力学计算和固溶处理过程中组织性能变化规律研究，提出了渐进式固溶处理方法。热力学计算结果显示，316H钢形成单一奥氏体组织的固溶温度为975.5～1 281 ℃。固溶实验研究显示，单段固溶处理的实验钢在1 050、1 100 ℃时，即可满足残余铁素体含量要求，但1 100 ℃时晶粒大小分布不均匀，混晶现象严重，导致实验钢塑性和韧性增高，但强度明显下降。采用1 000 ℃（1 h）+1 100 ℃（1 h）渐进式固溶处理，在保证铁素体含量和晶粒尺寸满足要求前提下，使得组织均匀性得到明显改善，强韧性高于单段固溶处理样品。

关键词: 316H奥氏体不锈钢, δ-铁素体, 晶粒尺寸, 渐进式固溶处理, 力学性能