等温淬火球铁组织与性能间的关系

本文研究了等温淬火球(ADI)的组织与性能之间的关系,热处理工艺对组织形态的影响。用贝氏体束间的残余奥氏体(A_(r-f))与大块的残余奥氏体(A_(r-b)的比值作为组织指标,发现当比值y=10左右时,等淬球铁有较佳的综合机械性能。降低等温温度可大大提高y值,使强度提高,但是由于残余奥氏体量也减少,从而对塑韧性不利,特别是残余奥氏体量小于25%,并出现下贝氏体后。块状残余奥氏体是非碳饱和的奥氏体,在一定条件下(温度、应力与应变),将发生非回火马氏体转变,导致脆性增加。等温淬火球铁在较佳的组织条件下,也有好的低温性能,残余奥氏体非常稳定。

Relationship Between Structure and Properties on ADI

The relationship between structure and properties on ADI and affecting of heat treatment process on structure are studied in this paper. Hence, the ratio (y=(A_(r-f))/(A_(r-b))) of the volume fraction of the retained austenite in bainitic strip (A_(r-f)) to that of the blocky type austenite (A_(r-b)) is used as structure indication, When y=10, the result which ADI has better synthetic mechanical properties is found. The ratio y is increased greatly by lowering austempering temperature, tensile strength is increased. But, because of retained austenitic guantity is reduced, especialy, when retained austenitic guantity is less than 25 percent and lower bainite is presented, plasticity and toughness will become worse. Blocky type austenite is non-carbon enriched austenite, at a certain condition (temperature, stress and strain ), nontempered martensite transformation will be took place in the blocky type austenite, that results in increasing brittleness. ADI also has good low temperature property and retained austenite is very stable at optimum structure condition