摘要
利用扫描电镜、金相显微镜、洛氏硬度计研究了P20塑料模具钢淬火及回火组织,并测定了硬度随淬火温度以及回火温度的变化。P20钢经830～920℃淬火得到板条马氏体,淬火后晶粒尺寸随淬火温度的升高有粗化的趋势但并不明显,直到890℃以后才明显粗化,因此,淬火温度应在830～890℃,以860℃为宜。P20钢硬度随回火温度升高而降低,碳化物析出增多并逐渐球化,马氏体板条边界逐渐变得模糊,有些板条合并变宽。P20钢经620℃×1h回火后其硬度为32.8～35.8HRC,能满足预硬化硬度要求,而且经830～890℃淬火+620℃×1h回火,硬度基本不随淬火温度变化,这将有利于工厂组织生产,因此最终选择预硬化工艺为860℃×30min淬火+620℃×1h回火。
P20 plastic die steel was treated at different quenching and tempering temperature. The quenching and tempering microstructure of P20 plastic die steel was investigated with scanning electronic microscope,metallurgical microscope and its hardness was measured with rockwell hardmeter. The experimental results show that the lath martensite is attained after the steel quenched from 830 ℃ to 920 ℃ and the grains of steel gradually increase with the elevation of quenching temperature,however the increase of the size is not obvious until the temperature is higher than 890 ℃. So quenching temperature can be set at 830 ～890 ℃ and 860 ℃ is a better choice. Tempering hardness decreases with the elevation of tempering temperature,precipitated carbide gradually spheroidizates and the amount gradually increases,martensite lath boundaries gradually become blurry and some laths are mergered and broadened with the elevation of tempering temperature. When 620 ℃ for 1 h is selected as tempering process,the tempering hardness is from 32.8 HRC to 35.8 HRC and it can satisfy pre-hardening hardness requirement. In addition,tempering hardness remains almost constant when the steel is quenched at 830 ～890 ℃ and tempered at 620 ℃,which is benefit for actual production in factory. So quenching at 860 ℃ for 30 min plus tempering at 620 ℃ for 1 h is finally selected as pre-hardening processes.
出处
《热加工工艺》
CSCD
北大核心
2010年第6期119-122,127,共5页
Hot Working Technology
基金
国家863计划项目资助项目(2007AA03Z511)
关键词
P20塑料模具钢
淬火
回火
微观组织
硬度
P20 plastic die steel
quenching
tempering
microstructure
hardness
作者简介
李勇（1981-），男，河南新蔡人，硕士研究生，主要从事钢铁材料热处理方面的研究；电话：0371-61530770；E—mail：liyongzzu@163．com
通讯作者：左秀荣（1967-），女，黑龙江齐齐哈尔人，教授，博士；电话：13007625618：E-mail：zuoxiurong@sohu．com
