【摘要】 研究了球铁经900℃奥氏体化后,在230℃(盐浴中)和25℃(油中)第一级等温淬火,325℃第二级(可控气氛炉中)等温淬火的组织与性能。发现经分级等温淬火后,球铁中贝氏体铁素体条束充分细化。230℃第一级等温淬火,时间在8～10min内,并经325℃×1.5h第二级等温淬火后,仍能获得细条束状的贝氏体组织。两种分级等温淬火工艺都能使球铁硬度达到HRC43,比325℃直接盐浴等温淬火提高5～6HRC。所以,分级等温是使球铁充分强化的有效手段,也为不用盐炉生产奥—贝球铁开劈了广阔的前景。更多还原

【Abstract】 The structure and properties of spheroidal graphite iron which was austenited at 9O0℃ and was first step austempered at 230℃ (in salt)or 25℃ (in oil), second step austempered at 325℃ (in controllable atmosphere)were studied. The results showed bainitic ferrite strip in ductile iron was less than austempered directly at 325℃ (in salt) after stepped austempering. Small strip bainite was obtained when first steppped austempering was at 230℃×(8～10)min. and second stepped austempered(at 320℃×1.5h). Hardness of spheroidal graphite iron could be gotten HRC43 after the two kind of stepped austempering and was (5～6)HRC higher than austempered directly at 325℃ (in salt), So that, stepped austempering will be an effective method by which SGI is strengthened greatlly and open up broad future for austenite-bainite ductile iron producted without salt bath furnance.更多还原