CM690锚链钢的表面“三角口”裂纹分析  

Analysis of Surface"Triangular Mouth"Crack on CM690 Anchor Chain Steel

作　　者：梁佰战 LIANG Baizhan(Jiangsu Shagang Group Huaigang Special Steel Co.,Ltd.,Huai'an 223002,China)

机构地区：[1]江苏沙钢集团淮钢特钢股份有限公司,江苏淮安223002

出　　处：《热加工工艺》2022年第5期155-157,161,共4页Hot Working Technology

摘　　要：CM690锚链钢在轧制过程中发现表面有“三角口”裂纹。从化学成分、缺陷形貌、金相和能谱四个方面对缺陷进行了分析,同时核查了冶炼和轧制过程。发现钢中化学成分的钛含量相对较低,且浇铸过程存在拉速频繁调整和过热度较高现象。分析认为钢材表面的“三角口”裂纹主要由铸坯表面横裂纹经过轧制变形所致。采用ThermoCalc软件计算了CM690钢的氮化物相图和不同含量氮化物析出温度的变化情况,研究了CM690钢表面“三角口”裂纹产生的机理。结果显示,裂纹是由于矫直温度刚好处于AlN氮化物析出温度范围内,AlN在晶界析出弱化了晶界结合力,而外加的矫直力最终导致了横向裂纹的产生。经过工艺优化,表面“三角口”裂纹再未出现。The surface "triangular mouth" crack in CM690 anchor chain steel was discovered during rolling process. The defects were analyzed from four aspects: chemical composition, defect morphology, metallography and energy spectrum. The smelting and rolling processes were also checked. It is found that the content of titanium in the chemical composition of steel is relatively low, and frequent adjustment of drawing speed and high superheat in casting process. It is concluded that the "triangle mouth " crack on the steel surface is mainly caused by the transverse crack of the billet surface through rolling deformation. The nitride phase diagram of CM690 steel and the temperature change of different content of nitride were calculated by using ThermoCalc software. A crack mechanism of "triangle mouth" on CM690 steel surface was studied. The results show that the crack is due to the straightening temperature is just in the AlN nitride precipitation temperature range,AlN the precipitation at the grain boundary weakens the grain boundary binding force, and the external straightening force finally leads to the transverse crack. After the process optimization, the surface "triangle mouth" crack did not appear again.

关 键 词：锚链钢 表面“三角口”裂纹 AlN氮化物 

分 类 号：TG335.5[金属学及工艺—金属压力加工]