Influence of martensite volume fraction and tempering time on tensile properties of partially austenitized in the (α + γ) temperature range and quenched + tempered ferritic ductile iron
Influence of martensite volume fraction and tempering time on tensile properties of partially austenitized in the (α + γ) temperature range and quenched + tempered ferritic ductile iron
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马氏体体积分数和回火时间对(α+γ)温度范围部分奥氏体化及调质铁素体球墨铸铁拉伸性能的影响
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
M. Erdoğan
中科院分区：
文献类型：
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作者：
M. Cerah;K. Kocatepe;M. Erdoğan
研究了马氏体体积分数和回火时间对双基体铁素体球铁拉伸性能的影响。为此，将试样在两相区（α + γ）中在795和815° C的不同温度下进行20 min的临界区间退火（部分奥氏体化），然后在100° C的油中淬火以获得不同的马氏体体积分数。出于比较的原因，一些试样也进行了常规热处理（在900° C下进行结晶化，然后淬火+回火）。结果表明，该钢形成了先共析铁素体+马氏体的组织，通过控制先共析铁素体和马氏体的体积分数，可以影响强度和塑性。从（α + γ）温度范围淬火的试样比常规热处理的试样表现出更大的延展性。随着马氏体含量的增加，抗拉强度提高，塑性下降。随着回火时间的延长，屈服强度和抗拉强度降低，塑性提高。回火3 h且马氏体体积分数（MVF）为62%的试样具有最佳的高强度和塑性组合。这种材料的拉伸应力和弹性极限远高于珠光体等级，延展性低于铁素体等级。回火3小时，并具有≥ 25%MVF的试样表现出最佳的高强度和延性的组合相比，铁素体等级。然而，它的强度略低，但延展性几乎是珠光体等级的三倍。
In the present study, the effect of martensite volume fraction and tempering time on the tensile properties of ferritic ductile iron with dual matrix structure was investigated. For this purpose, specimens were intercritically annealed (partially austenitized) in the two phase region (α + γ) at various temperatures of 795 and 815° C for 20 min and then quenched into oil held at 100° C to obtain different martensite volume fractions. Some specimens were also conventionally heat treated (austenitized at 900° C and then quenched + tempered) for a comparison reason. The results showed that a structure having proeutectoid ferrite plus martensite has been developed and volume fraction of proeutectoid ferrite and martensite can be controlled to influence the strength and ductility. Specimens quenched from the (α + γ) temperature range exhibited much greater ductility than conventionally heat treated specimens. The tensile strength increased and ductility decreased with increasing martensite content. By increasing the tempering time, the yield and UTS decreased and ductility increased. The specimens tempered for 3 h and having 62% martensite volume fraction (MVF) exhibited the best combination of high strength and ductility. The tensile and proof stress of this material is much higher than pearlitic grades and ductility is lower than ferritic grades. The specimen tempered for 3 h and having ∼ 25% MVF exhibited the best combination of high strength and ductility compared to ferritic grades. However its strength is slightly lower but the ductility is almost three times higher than pearlitic grades.