| 引用本文: | 雷勇,许晓嫦,李良,张奇,徐浩浩,赵凤晓.冷速及高温回火对低合金高强铸钢组织性能的影响[J].材料科学与工艺,2014,22(5):7-12.DOI:10.11951/j.issn.1005-0299.20140502. |
| LEI Yong,XU Xiaochang,LI Liang,ZHANG Qi,XU Haohao,ZHAO Fengxiao.Effect of cooling rate and high tempering on microstructure and mechanical properties of high-strength low-alloy(HSLA) cast steel[J].Materials Science and Technology,2014,22(5):7-12.DOI:10.11951/j.issn.1005-0299.20140502. |
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| 冷速及高温回火对低合金高强铸钢组织性能的影响 |
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雷勇,许晓嫦,李良,张奇,徐浩浩,赵凤晓
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(中南大学 材料科学与工程学院,长沙 410083)
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| 摘要: |
| 为提高低合金高强铸钢(HSLA)的综合力学性能,满足恶劣环境下的使用要求.采用光学显微镜、扫描电镜、透射电镜、冲击试验机、万能材料试验机研究了3种不同冷速及高温回火对HSLA铸钢组织与力学性能的影响.结果表明:随冷速增加,淬火组织发生由多边形铁素体+针状铁素体+粒状贝氏体→粒状贝氏体+板条贝氏体→准上贝氏体+板条马氏体的演变.冷速为1 ℃/s的空冷样,具有最高的塑韧性；冷速最大的水冷样,其强度、硬度最高.冷却样经580 ℃回火,其晶界、板条界均有粒状、短棒状的纳米第二相析出,EDS分析表明,100~200 nm的析出相为合金渗碳体(M3C),而50 nm以内的析出相为(V,Ti)(C,N).空冷样回火后有较高强度、最高的塑韧性；油冷、水冷样回火后,Re提高,Rm略有下降,AkU降低与高温回火脆性的发生有关,但-40 ℃的AkU仍有60、40 J,具有较好的低温冲击韧性.可见,试验HSLA铸钢表现出良好的综合力学性能,能满足在恶劣环境下的使用要求. |
| 关键词: 低合金高强铸钢 冷却速率 高温回火 微观组织 力学性能 |
| DOI：10.11951/j.issn.1005-0299.20140502 |
| 分类号:TG142.1 |
| 基金项目:长沙市科技计划资助项目(K1207019-11). |
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| Effect of cooling rate and high tempering on microstructure and mechanical properties of high-strength low-alloy(HSLA) cast steel |
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LEI Yong,XU Xiaochang,LI Liang,ZHANG Qi,XU Haohao,ZHAO Fengxiao
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(School of Materials Science and Engineering,Central South University, Changsha 410083,China)
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| Abstract: |
| To improve comprehensive mechanical properties of high strength low alloy(HSLA) cast steel, and meet application requirements of HSLA cast steel in harsh environments, the mechanical properties and microstructures of HSLA cast steel cooled at three different cooling rates and subsequently tempered at 580 ℃ were studied by optical microscope, scanning electron microscopy, transmission electron microscopy, impact tester and universal material test. With the cooling rate increasing, the microstructure evolved from ferrite + granular bainite, lath bainite, to lath martensite + quasi upper bainite. Higher plasticity and toughness were obtained at a slower cooling rate of 1 ℃/s. Water cooled sample had maximum strength and hardness, at the expensive of impact energy slightly. Nano-precipitates of granular, short rod were found along grain, lath boundary in cooled samples after tempering. EDS analysis revealed that the precipitates of 100～200 nm were M3C, and that within 50 nm in size were (V,Ti)(C,N). The maximum plasticity and toughness(elongation rate A=27% impact energy, Charpy U-notch impact energy AkU=113 J at -40 ℃) were achieved by air cooled sample after tempering. The yield strength of specimen after cooling and tempering increased, the occurrence of high temperature temper brittleness led to reduction of impact toughness, whereas impact energy was remained 60 J, 40 J at -40 ℃, respectively. |
| Key words: HSLA cast steel cooling rate high tempering microstructures mechanical properties |
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