S32205双相不锈钢中σ相的析出及其对力学性能的影响

来源期刊：钢铁2010年第7期

论文作者：刘复兴

文章页码：62 - 65

关键词：双相不锈钢； 时效时间； σ相； 组织； 性能

Key words：duplex stainless steel； aging time； σ phase； microstructure； property

摘    要：对S32205双相不锈钢在850℃进行时效处理,采用光镜、扫描电镜、能谱仪、硬度和拉伸测试等手段研究了σ相的析出规律及其对力学性能的影响。结果表明:时效15 min后σ相开始沿γ/α或α/α晶界析出,并向铁素体一侧长大,其析出反应为铁素体发生转变形成σ相和γ₂相;时效时间延长,σ相的析出量增加,时效240 min后σ相的含量达到18%,并导致双相不锈钢的硬度明显增加、强度略有提高,而塑性显著下降;拉伸断口的断裂类型由典型的韧性断裂向以准解理断裂为特征的脆性断裂转变。

Abstract: The aging treatment for S32205 duplex stainless steel was preformed at 850 ℃.σ phase precipitation and its effect on mechanical properties of S32205 duplex stainless steel were analyzed by OM,SEM,EDS,hardness measurements and tensile tests.The results show that σ phase begins to nucleate at γ/α or α/α interfaces after 15 min aging,and then grows into the surrounding ferrite areas.The formation mechanism is a transformation of α into γ₂ and σ.The amount of σ phase increases with prolonging aging time,which achieves 18% when aging for 240 min,and the formed σ phase in S32205 duplex stainless steel leads to an obvious increase in the hardness,a certain increase in the strength and a sharp decrease in the ductility.The types of tensile fracture are changing from the typical ductile rupture to the brittle fracture characterized by quasi-cleavage crack.