THE DEVELOPMENT OF Ni-CONTAINING CRYOGENIC STEELS AND THEIR INDUSTRIAL MANUFACTURING
China has become one the largest energy consumer in the world due to the rapid growth of its economy,leading to the steady increase in the consumption of LPG,LEG and LNG in recent years.Therefore,urgent demands for the steels to be able to contain liquefied gases had emerged.Nickel containing cryogenic steels had been mainly used for liquefied gas tanks as ferritic cryogenic materials,but there are still many problems in regard of industrial production.In the present work,the optimized processing routes for 5Ni and 9Ni steels were developed at laboratory.The effect of Ni addition on the microstructure and cryogenic toughness of Ni containing steels was investigated.The results showed that the prior austenite grain size decreased from 19.8μm to 18.2μmand the ductile-brittle transition temperature decreased as Ni content increased from 5%to 9%.The quenched and tempered microstructures in 5Ni and 9Ni steels were consisted of tempered martensite and small amount of reversed austenite,with the microstructure of 5Ni steel only containing only 0.3%reversed austenite and a large amount of dispersive cementite was precipitated on ferritic matrix.With the increase of Ni addition up to 9%,the volume fraction of reversed austenite increased to about 5%and cementite precipitation was eliminated because the reversed austenite had absorbed carbon atoms from the matrix.It has been shown that cementite was harmful to the toughness of the steelas a hard second phase because it was easy for cracks initiation and propagation when the cementite was precipitated at grain boundaries or lath boundaries.Fine grain size,more reversed austenite and less cementite precipitation are worked out to be the key factors to decrease the ductile-brittle transition temperature of 9Ni steel.
Ni serial Cryogenic Steels QT Heat Treatment Reversed Austenite Cementite Cryogenic Toughness
Meng Wang Zhang-long Xie Cheng-gang Li Zheng-yu Liu
State Key Laboratory of Rolling and Automation Northeastern University,Shenyang,China NISCO Technology Quality Department,Nanjing,China
国际会议
Energy Materials 2014(第一届能源材料国际会议)
西安
英文
903-909
2014-11-04（万方平台首次上网日期，不代表论文的发表时间）