高强度锻件用微合金化钢

Microalloyed Steels for High-strength Forgings

过去35年,已经开发出两大类高强度棒材和锻件用微合金化(MA)钢。第一类是1974年开发的,为中碳钢中加入少量的铌或钒。这些早期的中碳钢为珠光体-铁素体组织,具有高的强度和良好的高周疲劳性能。大约15年之后,微合金化多相钢被开发出来,根据材料加工工艺不同,组织由铁素体、贝氏体、马氏体以及残余奥氏体等组成。这类钢可以达到非常高的强度,同时具有良好的疲劳性能和高的断裂性能。在20世纪70年代早期,高强度锻件仅能通过最终的热处理过程实现,热处理包括加热、淬火及回火(QT)。已经不断地被证实由MA珠光体-铁素体钢生产的空冷锻件可以实现与更昂贵的热处理锻件类似的强度和疲劳性能。介绍过去35年来微合金化珠光体-铁素体钢的发展。

In the past thirty-five years, two families of microalloyed（MA） steels have been developedfor high strength bar and forging applications. The first family was introduced in 1974 and represented themedium carbon steels to which were added small amounts of niobium or vanadium. These early mediumcarbon contents steels exhibited pearlite-ferrite microstructures and showed good strength and high-cyclefatigue resistance. About 15 years later, microalloyed multiphase steels were introduced, which had mi-crostructures comprised of mixtures of ferrite, bainite, martensite, and retained austenite, depending onthe composition and processing. These steels were capable of reaching very high strengths, with good fa-tigue resistance and high fracture resistance. Prior to the early 1970 s, high strength forgings could be ob-tained only by final heat treatment, involving reheating, quenching and tempering（ QT）. It has beenshown repeatedly that the air cooled forgings made from MA pearlite-ferrite steels can exhibit strengthsand fatigue resistances similar to those of the more expensive heat treated forgings. This paper will followthe development of the microalloyed pearlite-ferrite steels over the past 35 years.