摘要
采用检测分析方法对预应力钢绞线SWRH82B锥形断裂机理进行研究,制定相应解决措施,并进行工业试验验证。研究表明:SWRH82B钢绞线锥形断裂主要受两方面影响,一是C、Mn、Cr、S元素偏析,C偏析导致锥形断裂样品形成了网碳组织,Mn、Cr元素促进不良马氏体组织形成,硫化物偏聚降低了晶界与晶界间的结合力,致使SWRH82B钢的塑性变差;二是钢液洁净度较差,结晶器出现卷渣导致大颗粒的异物夹杂存在,中心裂纹区域尺寸较大,最大夹杂物尺寸高达174.16μm,平均尺寸达到28.30μm,并且存在MgO-Al_(2)O_(3),CaO-MgO-Al_(2)O_(3)-SiO_(2)等脆性夹杂物,降低SWRH82B钢的拉拔性能。通过降低钢水过热度和拉速,提高二冷水比水量,降低LF精炼渣中碱度及MgO含量,钢液中w(S)控制在0.006%以下,延长LF精炼软吹时间等优化措施,提高其拉拔性能。优化后SWRH82B钢盘条中心偏析、网状碳化物、中心马氏体评级均分别控制在0~0.5级,索氏体比例提高至85%~90%。盘条中心夹杂物最大尺寸和平均尺寸分别降至42.10μm和16.70μm,钢中主要夹杂物为CaO-Al_(2)O_(3)-SiO_(2),拉丝断头率降至每百吨1.12次,捻股断头率0.35次/趟,SWRH82B预应力钢绞线锥形断裂率大幅下降,拉拔性能得到改善。
The reason for the cone fracture of prestressed steel strand SWRH82 B was studied, and corresponding solutions were formulated. The industrial test verification is carried out, and research results show that, cone fracture of prestressed steel strand SWRH82 B is mainly affected by two aspects. One is the segregation of C, Mn, Cr, and S elements. The segregation of C leads to the formation of a network carbon structure in the sample of cone fracture. Mn and Cr elements promote the formation of poor martensite structure, and the segregation of sulfide reduces the bonding force between the grain boundary and the grain boundary, and leads to poor plasticity of SWRH82 B steel. The second is the poor cleanliness of the molten steel. The entrainment of slag in the mold leads to the presence of large particles of foreign matter inclusions. The size of the central crack area is larger. The maximum inclusion size is as high as 174.16 μm, and the average size is 28.30 μm, and there are brittle inclusions such as MgO-Al_(2)O_(3) and CaO-MgO-Al_(2)O_(3)-SiO_(2),which affect the drawing performance of SWRH82 B steel.The drawing performance is improved by reducing the superheat and casting speed of the molten steel, increasing the water ratio of the secondary cooling, reducing the alkalinity and MgO content in the LF refining slag, controlling the S mass fraction in the molten steel below 0.006 %, extending the LF refining soft blowing time and other optimization measures. After optimization, the center segregation, network carbide, and center martensite in SWRH82 B steel wire rod are respectively controlled at 0-0.5 level, and the proportion of sorbite increases to 85 %-90 %. The maximum size and average size of the central inclusions in wire rod reduce to 42.10 μm and 16.70 μm respectively. The main inclusions in the steel are CaO-Al_(2)O_(3)-SiO_(2), the wire breakage rate reduces to 1.12 times/100 t, and the twisted strand breakage rate is 0.35 times/trip, cone breaking rate of prestressed steel strand SWRH82 B is great
作者
张振全
张明博
ZHANG Zhenquan;ZHANG Mingbo(Chengde Branch of HBIS Co.,Ltd.,Chengde 067102,China)
出处
《炼钢》
CAS
北大核心
2021年第3期74-80,共7页
Steelmaking
关键词
SWRH82B钢
元素偏析
非金属夹杂物
锥形断裂
SWRH82B steel
element segregation
non-metallic inclusion
cone fracture mechanism
