20CrMnTi钢连铸坯的高温热塑性  

HIGH TEMPERATURE THERMOPLASTIC OF 20CrMnTi STEEL CONTINUOUS CASTING BILLET

作　　者：王程明 孙晓冉 李秋曈 赵楠 谷秀锐 Wang Chengming;Sun Xiaoran;Li Qiutong;Zhao Nan;Gu Xiurui(HBIS Materials Technology Research Institute,Shijiazhuang 050000,Hebei)

机构地区：[1]河钢材料技术研究院,河北石家庄050000

出　　处：《河北冶金》2023年第8期25-28,共4页Hebei Metallurgy

摘　　要：利用Gleeble-3800热模拟试验机研究了20CrMnTi钢连铸坯的高温热塑性,结合扫描电子显微镜和金相显微镜观察了拉伸断口形貌及其附近金相组织,分析了试验钢断裂机理。结果表明:在600~1300℃温度区间内,试验钢抗拉强度逐渐下降,断面收缩率先下降后升高再降低;在900℃时断面收缩率达到最小值48%,断口形貌呈冰糖状,为典型的沿晶脆性断裂,断口附近组织为贝氏体和部分铁素体;断面收缩率在1150℃时达到最大值82.36%,断口韧窝较为集中,为典型的韧性断裂,断口附近组织为均匀的贝氏体。试验钢在600~1300℃范围存在1个脆性温度区间,即750~950℃第Ⅲ脆性区间;塑性区间为600~700℃和1000~1300℃。第Ⅲ脆性区间形成原因是由于铁素体沿晶界析出,削弱了晶界结合力,为裂纹的产生和扩展提供了条件,导致材料塑性恶化。为减少裂纹的发生率,在连铸生产中应避开第Ⅲ脆性区间,即控制矫直温度高于950℃或者低于750℃。The high-temperature thermoplastic of 20CrMnTi steel continuous casting billet was studied by Gleeble-3800 thermal simulation testing machine,and the tensile fracture morphology and its nearby metallographic structure were observed by scanning electron microscope and metallographic microscope,and the fracture mechanism of the test steel was analyzed.The results show that in the temperature range of 600~1300℃,the tensile strength of the test steel gradually decreases,and the section shrinkage decreases first,then increases and then decreases.At 900℃,the section shrinkage reached a minimum of 48%,and the fracture morphology was rock sugar,which was a typical brittle fracture along the crystal,and the structure near the fracture was bainite and partial ferrite.The section shrinkage reached a maximum of 82.36%at 1150℃,and the fracture ligament was relatively concentrated,which was a typical ductile fracture,and the tissue near the fracture was uniform bainite.The test steel has one brittle temperature range in the range of 600~1300℃,that is,750~950℃III.brittle interval,the plastic range is 600~700℃and 1000~1300℃.The formation of the III.brittle interval is due to the precipitation of ferrite along the grain boundary,which weakens the grain boundary bonding force,provides conditions for the generation and propagation of cracks,and leads to the deterioration of material plasticity.In order to reduce the incidence of cracks,the third brittle zone should be avoided in continuous casting production,that is,the control straightening temperature is higher than 950℃or lower than 750℃.

关 键 词：20CrMnTi 高温热塑性 断口 沿晶断裂 韧性断裂 第Ⅲ脆性区间 

分 类 号：TG142.1[一般工业技术—材料科学与工程]