According to the abnormal fracture phenomenon of 87MnSi steel wire rod for bridge cable， the evolution of microstructure and mechanical properties during production processing were systematically analyzed. The results show that the microstructure of the rod is composed of pearlite and a small amount of proeutectoid ferrite， and the cementite lamellae are randomly distributed. After cold drawing， the cementite lamellae are rotated or fibrotic， and some cementite are broken and dissolved， the dissolution amount is 1.40wt.%（9.69%）. After ho-dip galvanizing， the dissolved cementite is spheroidized. In the process of cold drawing， hot-dip galvanizing and stabilization treatment， the microhardness of wire rod （329.8HV） increases （450.2HV） firstly， then decreases （447.9HV） and increases （474.8HV） finally. The cementite dissolved in the cold drawing process increases the hardness of the steel wire to 468.3HV， while the spheroidized cementite in the hot galvanizing process decreases the hardness to 439.8HV， and deteriorates tensile property. When the degree of spheroidization of cementite on the edge is obvious， the microstructure and mechanical properties of the steel wire inside and outside are greatly different， and the fracture is eventually caused by uneven force during stabilizing treatment.

ER70S-6盘条生产焊丝出现拉拔断裂,通过对断裂样品进行电镜扫描以及金相分析,发现贝氏体和马氏体复合相组织是造成断裂的直接原因.根据该组织形成机制从元素偏析和轧后控冷两个方面分析,提出并实施延长盘条出罩时间、强化盘条保温效果等措施,改善盘条基体组织,解决了断丝问题.

针对弹簧钢盘条加工过程中出现断裂的问题,对盘条组织性能进行了分析,发现盘条表面存在脱碳层和马氏体组织是盘条冷弯断裂的根本原因.通过对盘条化学成分及控轧控冷工艺的优化控制,亦即采用低的加热温度、低的开轧温度、低的吐丝温度以及先快后慢的控冷方式,消除了盘条表面的异常组织,解决了弹簧断裂问题.

介绍胎圈钢丝用合金盘条C82DACr的轧制开发过程.通过合理的轧制工艺,盘条获得了较为理想的力学性能和金相组织,其索氏体化率达到85％以上,并对产品后期加工进行跟踪,盘条经客户使用,效果良好.

Different cooling rate has great influence on the mechanical properties and microstructure of 55SiCr spring steel after rolling.During the phase change and transition,the 55SiCr spring steel wire is treated with different cooling rate,and take sample to test the mechanical properties and microstructure.Results show that with the increase of the cooling rate of the high temperature section,the tensile strength of the samples increased gradually,the reduction of area increased first and then decreased,the depth of the decarburization layer decreased gradually.When the cooling rate increases rapidly,it is easy to produce abnormal martensite,causing brittle fracture.Therefore,the cooling process of the 55SiCr spring steel wire after rolling,cooling fast to 690 C or so at the appropriate cooling rate,and then into the heat holding cover,completing phase change,get excellent performance,small decarburization depth and high sorbite rate microstructure spring steel wire rod.

The production flowsheet of ø9~ ø12 mm wire rod o£ spring steel 60Si2MnA is 100 t BOF-LF-VD-150 mm x 150 mm billet casting-high speed wire rolling process. The decarburization mechanism is discussed and the effective factors on decarburization are analyzed. With the process measures including suitable decreasing the temperature of second heating zone and rising the temperature of soaking zone, decreasing the total heating time of billet from 2. 7 h to 1. 5 h, controlling oxygen content in furnace being 3% ~ 5% , decreasing beginning rolling temperature and finishing rolling temperature respectively from (1 000 ± 20 )℃ and (850 ± 20 ) ℃to ( 950 ± 20)℃and ( 820 ± 20 )℃ ,reducing the wind cooling time for wire rod at temperature more than 727 X. , the full ferrite decarburization layer of wire rod of spring steel 60Si2MnA decreases from 0. 072 mm to 0, the total decarburization layer decreases from 0. 142 mm to 0. 063 mm, and the fatigue life of spring increases from 17. 7 x 104to 23. 2 x 104.