工程科学学报，第38卷，第11期：1559-1568,2016年11月 Chinese Journal of Engineering,Vol.38,No.11:1559-1568,November 2016 D0l:10.13374/j.issn2095-9389.2016.11.008:http://journals.ustb.edu.cn Al对热挤压模具钢SDAH13连续冷却转变规律的 影响 盛振栋12》，左鹏鹏2》，吴晓春12,3》区 1)省部共建高品质特殊钢治金与制备国家重点实验室，上海2000722)上海市钢铁治金新技术开发应用重点实验室，上海200072 3)上海大学材料科学与工程学院，上海200072 ☒通信作者，E-mail:wuxiaochun(@t.shu.cdu.cn 摘要采用热膨胀仪测定A1质量分数分别为0.77%和1.43%以及无A1的热挤压模具钢SDAH13的连续冷却转变曲线， 并结合光学显微镜、扫描电镜及显微硬度仪分析A元素对SDAH13钢相变点、连续转变规律、组织以及硬度的影响.结果表 明：A元素显著提高SDAHI3钢的AC,、AC,和Ms点，降低淬火残留奥氏体含量，同时扩大铁素体及奥氏体两相区.在I060℃ 奥氏体化温度下，A元素对SDAH13钢贝氏体相变的临界冷速(0.30℃·s)无明显影响，但使贝氏体相区变宽，A1质量分数 分别为0.77%和1.43%的SDAH13钢的珠光体相变的临界冷速(0.05℃·s和0.3℃·s)均高于无A1的SDAH13钢的临界 冷速(0.02℃·g),且A1质量分数为1.43%的SD4H13钢在0.02-0.08℃·s冷速下出现先共析铁素体组织.A1的加入 还使SDAH13钢淬火硬度有所降低. 关键词模具钢：热挤压：铝元素：相变点：连续冷却转变 分类号TG151.2 Effect of Al on the continuous cooling transformation characteristic of hot extrusion die steel SDAH13 SHENG Zhen-dong,ZUO Pengpeng,WU Xiao-chun 1)State Key Laboratory of Advanced Special Steel,Shanghai 200072,China 2)Shanghai Key Laboratory of Advanced Ferrometallurgy,Shanghai 200072,China 3)School of Materials Science and Engineering,Shanghai University,Shanghai 200072,China Corresponding author,E-mail:wuxiaochun@t.shu.edu.cn ABSTRACT The continuous cooling transformation (CCT)diagrams of SDAH13 hot extrusion die steels with different mass fractions of Al (0.77%and 1.43%)and without Al were measured by dilatometry.The effects of Al on the CCT diagrams,microstructure and hardness of SDAH13 steels were studied by optical microscopy,scanning electron microscopy (SEM)and Vickers hardness test.The results show that the phase transformation temperature points(Ac,Ac and Ms)of SDAH13 steels significantly increase,the contents of retained austenite in the quenched steels decrease,and the aymulti-phase region expands with the increase in mass fraction of Al. However,when austenited at 1060C,Al has no obvious influence on the critical cooling rate (0.30C.s)of bainite transforma- tion,but bainite phase region broadens.Meanwhile,the critical cooling rates of pearlite transformation of SDAH13 steels with the Al content of 0.77%and 1.43%are 0.05Csand 0.3Cs,respectively,which are higher than the critical cooling rate (0.02 Cs)of pearlite transformation of SDAH13 steel without Al.Pro-eutectoid ferrite appears at the cooling rate from 0.02 Csto 0.08C'swhen the mass fraction of Al reaches 1.43%.Nevertheless,the quenched hardness decreases with Al addition. KEY WORDS die steels;hot extrusion;aluminum:phase transformations points;continuous cooling transformation 收稿日期：2016-03-01 基金项目：国家科技支撑计划资助项目(2007BAF51B04)工程科学学报，第 38 卷，第 11 期: 1559--1568，2016 年 11 月 Chinese Journal of Engineering，Vol． 38，No． 11: 1559--1568，November 2016 DOI: 10． 13374 /j． issn2095--9389． 2016． 11． 008; http: / /journals． ustb． edu． cn Al 对 热 挤 压 模 具 钢 SDAH13 连续冷却转变规律的 影响 盛振栋1，2，3) ，左鹏鹏1，2，3) ，吴晓春1，2，3)  1) 省部共建高品质特殊钢冶金与制备国家重点实验室，上海 200072 2) 上海市钢铁冶金新技术开发应用重点实验室，上海 200072 3) 上海大学材料科学与工程学院，上海 200072  通信作者，E-mail: wuxiaochun@ t． shu． edu． cn 摘 要 采用热膨胀仪测定 Al 质量分数分别为 0. 77% 和 1. 43% 以及无 Al 的热挤压模具钢 SDAH13 的连续冷却转变曲线， 并结合光学显微镜、扫描电镜及显微硬度仪分析 Al 元素对 SDAH13 钢相变点、连续转变规律、组织以及硬度的影响． 结果表 明: Al 元素显著提高 SDAH13 钢的 Ac1、Ac3和 Ms 点，降低淬火残留奥氏体含量，同时扩大铁素体及奥氏体两相区． 在 1060 ℃ 奥氏体化温度下，Al 元素对 SDAH13 钢贝氏体相变的临界冷速( 0. 30 ℃·s － 1 ) 无明显影响，但使贝氏体相区变宽，Al 质量分数 分别为 0. 77% 和1. 43% 的 SDAH13 钢的珠光体相变的临界冷速( 0. 05 ℃·s － 1 和0. 3 ℃·s － 1 ) 均高于无 Al 的 SDAH13 钢的临界 冷速 ( 0. 02 ℃·s － 1 ) ，且 Al 质量分数为 1. 43% 的 SDAH13 钢在 0. 02 ～ 0. 08 ℃·s － 1 冷速下出现先共析铁素体组织． Al 的加入 还使 SDAH13 钢淬火硬度有所降低． 关键词 模具钢; 热挤压; 铝元素; 相变点; 连续冷却转变 分类号 TG151. 2 收稿日期: 2016--03--01 基金项目: 国家科技支撑计划资助项目( 2007BAE51B04) Effect of Al on the continuous cooling transformation characteristic of hot extrusion die steel SDAH13 SHENG Zhen-dong1，2，3) ，ZUO Peng-peng1，2，3) ，WU Xiao-chun1，2，3)  1) State Key Laboratory of Advanced Special Steel，Shanghai 200072，China 2) Shanghai Key Laboratory of Advanced Ferrometallurgy，Shanghai 200072，China 3) School of Materials Science and Engineering，Shanghai University，Shanghai 200072，China  Corresponding author，E-mail: wuxiaochun@ t． shu． edu． cn ABSTＲACT The continuous cooling transformation ( CCT) diagrams of SDAH13 hot extrusion die steels with different mass fractions of Al ( 0. 77% and 1. 43% ) and without Al were measured by dilatometry． The effects of Al on the CCT diagrams，microstructure and hardness of SDAH13 steels were studied by optical microscopy，scanning electron microscopy ( SEM) and Vickers hardness test． The results show that the phase transformation temperature points ( Ac1，Ac3 and Ms) of SDAH13 steels significantly increase，the contents of retained austenite in the quenched steels decrease，and the α-γ multi-phase region expands with the increase in mass fraction of Al． However，when austenited at 1060 ℃，Al has no obvious influence on the critical cooling rate ( 0. 30 ℃·s － 1 ) of bainite transforma￾tion，but bainite phase region broadens． Meanwhile，the critical cooling rates of pearlite transformation of SDAH13 steels with the Al content of 0. 77% and 1. 43% are 0. 05 ℃·s － 1 and 0. 3 ℃·s － 1 ，respectively，which are higher than the critical cooling rate ( 0. 02 ℃·s － 1 ) of pearlite transformation of SDAH13 steel without Al． Pro-eutectoid ferrite appears at the cooling rate from 0. 02 ℃·s － 1 to 0. 08 ℃·s － 1 when the mass fraction of Al reaches 1. 43% ． Nevertheless，the quenched hardness decreases with Al addition． KEY WOＲDS die steels; hot extrusion; aluminum; phase transformations points; continuous cooling transformation