Heredity in the Microstructure and Mechanical Properties of Hot-rolled Spring Steel Wire 60Si2MnA during Heat Treatment Process

Heredity in the microstructure and mechanical properties of hot-rolled spring steel wire 60Si2MnA during heat treatment process was investigated comprehensively. The steel was isothermally transformed to obtain various hot-rolled microstructure （pearlite fineness within the range of 140-510 nm） and mechanical properties, and followed by some quenching-tempering treatment. Afterwards, microstructure was characterized by optical microscopy, scanning electron microscopy and quantitative metallography, and mechanical properties were determined by tensile test. The results indicated that the hot-rolled microstructure with a coarsen pearlite structure had been changed after reheating, to a austenite microstructure with bigger and more uneven grain size, and finally to a coarsen tempered microstructure. And the average austenite grain size and standard deviation of its distribution in quenched microstructure were observed to depend linearly on the interlamellar spacing in hot-rolled microstructure. Besides, to obtain a good combination of the final strength and plasticity, an optimum value range （190-280 nm） of the interlamellar spacing had been determined for the interlamellar spacing in hot-rolled microstructure.

50CrVA弹扁表面纵向裂纹的原因分析与预防

通过金相与EDS分析,确定了50CrVA弹扁表面纵向裂纹产生的原因为钢中的气体。针对性地采取了多项预防措施,取得了明显效果。

应用统计技术进行60Si2Mn扁钢脱碳分析

介绍了60Si2Mn弹簧扁钢脱碳改进中加热制度原则的确定过程,在弹簧方坯和成品扁钢脱碳改进的测量和分析过程中应用了统计技术,直观、定量找出了脱碳产生原因的瓶颈,提出了进一步的改进措施,探讨了统计技术在品质改进中的重要作用。

热轧弹扁宽度尺寸超差原因分析及改进措施

介绍了热轧弹簧扁钢的生产工艺流程,分析了中、精轧机组孔型设计、进出口导卫设计的不合理和压下量过大等主要影响成品材宽度波动的因素,提出了相应对策。通过技术改进,小规格弹扁的成材率、合格率逐步提高。

新型深孔立轴式回转器的研制

介绍了新型立轴式钻机的回转器与给进装置的结构特点与技术参数,以及产品在项目工地的实际应用情况。产品汲取了国内外全液压动力头的优点,具有给进行程长,维修方便等特点。

南钢转炉生产60Si2Mn弹簧扁钢的品质控制

采用65 t顶底复吹转炉—65 tLF炉—150 mm×150 mm方坯连铸机—铸坯缓冷流程成功地开发了60Si2Mn弹簧扁钢。实践表明,窄成分控制,转炉高碳出钢,LF精炼炉白渣操作和确保软吹时间,连铸保护浇注和电磁搅拌控制,以及铸坯堆缓冷或缓冷坑缓冷工艺,能实现60Si2Mn弹簧扁钢机械性能符合国标要求和疲劳寿命在10万次以上。