高速钢钢锭锻前加热工艺研究

高速钢钢锭锻前加热质量对后续的锻造工艺影响至关重要,对M42高速钢钢锭的锻前加热工艺进行了研究。理论计算了M42钢的晶界熔化温度和变形加热温度,结合生产经验设计试验方案,将试样在不同的加热工艺下加热,然后对加热后的组织进行观察分析,从而得出最理想的锻前加热工艺。研究结果表明,M42钢锭最优的高温保温段加热工艺:1 150℃×5 h,为实际生产应用提供理论参考。     

闪光焊机顶锻初始间隙的工艺探究

通过对闪光焊机顶锻初始间隙与焊接工艺关联性验证,分析了闪光对焊过程是多参数控制的焊接过程,且相互关联交互影响,结果表明初始间隙对于焊缝质量的显著影响;基于顶锻初始间隙影响因素的研究,分析制定了顶锻初始间隙的焊接工艺设计标准。     

重载铁路钢轨钢连铸重压下工艺研发及应用

与普通铁路相比，重载铁路的运输具有大轴重、高牵引质量、大运量的特点，对钢轨的质量要求更为严苛。大断面连铸坯作为重载铁路钢轨钢生产的重要母材，提升母材连铸坯的质量才是决定重载铁路钢轨钢质量的关键。为了解决大断面连铸坯的内部质量问题，首先采用数值计算方法，研究了重轨钢连铸大方坯重压下过程的变形行为，为重压下工艺及装备设计提供了理论依据。在此基础上，结合现场生产实践，系统对比并分析了轻压下与重压下工艺对重载铁路钢轨钢内部质量的影响，证明了实施重压下工艺可以大幅度提升重轨钢的内部质量。     

浅论冷拔用钢与顶锻用钢的关系

用优质碳素结构钢和合金结构钢生产的圆钢，大部分产品以“热顶锻”状态交货，被广泛地用于机械加工行业，制造各式各样的零部件，这种材料具有良好组织结构及表面质量，热顶锻后钢材不开裂，用户将该种材料广泛用于冷拔加工生产，在实际生产过程中，热顶锻用钢用于冷拔时经常发生一些表面质量问题，由此而引发质量异议，本着重分析冷拔用钢与顶锻用钢的关系。     

低温轧制与热轧工艺润滑

在压力膨胀仪和Gleeble—1500试验机上对25SiMn钢和AY3F钢进行了不同温度,不同变形速率和不同变形程度时变形抗力的模拟,并与实验室相应条件下测定的轧制压力进行了比较。同时测定了加热和轧制所需的能耗。试验了热轧工艺润滑对降低变形抗力的效果。结果表明,降低加热温度可大大节省加热和轧制所需的总能耗;采用热轧工艺润滑可以补偿由于低温轧制所增加的部分轧制能耗。     

轧后热处理温度对热轧钢轨组织和性能的影响

 通过在Gleeble-1500热模拟试验机上对珠光体钢轨的轧后热处理模拟试验,研究了热轧后不同加热温度进行奥氏体化后,同一等温温度下得到的珠光体轨钢的显微组织和力学性能。试验结果表明：与热轧态相比,热处理后的钢轨钢在保持硬度稳定的基础上,冲击韧性随着奥氏体化温度降低得到明显改善。观察轧后热处理钢轨的组织,从原始奥氏体晶粒尺寸、相变后珠光体组织中珠光体域的尺寸和珠光体片层间距大小等方面,对轧后热处理温度对热轧钢轨性能的影响规律和原因进行了分析,阐明了轧后热处理温度对于控制珠光体钢轨的组织和性能的影响作用。     

GH99合金锻棒的研制

介绍了宝山钢铁股份有限公司特钢事业部首次生产GH99合金锻棒的研究工作。通过热力学相图计算制定了2000t快锻机生产GH99合金棒材的终锻温度以及相应的钢锭加热温度,研究了不同加热温度和终锻温度对GH99合金Φ250快锻棒材组织和性能的影响。结果表明,锻棒横低倍组织无缺陷,但是,加热温度和终锻温度过低时,棒材表面会因变形温度低于动态再结晶温度而残留部分原始拉长晶粒。加热温度和终锻温度过高时,因原始晶粒在加热过程中过分长大,边缘处在变形过程中残留部分大的原始拉长晶粒。在合适的加热温度和终锻温度下,棒材的心部、R/2处和表面均获得了均匀且较细小的晶粒组织,在此条件下,合金具有良好的室温、高温综合性能。     

重轨坯火焰清理温度对成品钢轨裂纹的影响

介绍了在不同温度下进行火焰清理对比试验，确定钢坯清理部位生产裂纹的初始温度、实验室模拟重民制变形及进行裂纹焊合轧制试验，结果表明：钢坯火焰清理生产的裂纹，经热轧变形后仍有部分大能焊合，即钢轨钢的初始清理温度应≥２００℃。     

钒对30MnSi钢热变形行为的影响

通过对30MnSi和30MnSiV两种钢在Gleeble-1500热模拟试验机上的高温压缩变形实验，分析了不同变形条件下微合金元素钒对变形抗力的影响，通过试验数据的计算可知，30MnSiV钢的再结晶激活能比30MnSi钢大6.7%左右。     

形变条件对A3F钢变形抗力和组识的影响

本文通过热模拟试验测定了不同形变条件下A3F钢的变形抗力、并利用电子显微镜和光学显微镜，观察了不同变形温度。不同变形速度以及不同变形程度的热模拟试样的微观组织，分析了形变条件对A3F钢的变形抗力及组织的影响。     

Processing practice of Baosteel drill pipes

Drill pipe products are the most critical service requirement,the highest performance requirement and the highest quality reliability OCTG products.Through the continuous research on steelmaking,upset, heart treatment,straightening and friction welding,Baosteel improves the key technical parameters which affect the quality of drill pipe,such as material purity,Miu of internal upset transition area,toughness and straightness.Baosteel drill pipe products have met the demanding requirement of drilling operations.By BRP dephosphorization and LF desulfurization,the P,S content of Baosteel drill pipe is very low.The S content of S-135 drill pipe can be controlled in less than 10ppm.Baosteel designs a new closed-loop control system of upset end induction heating system.The system use temperature measurement inside the oven and closed-loop control.The temperature accuracy of the system can be guaranteed within the±15℃to get a stable upset quality.The upsetting process of the drill pipe is optimized by using patented technology and made the Miu from 100 mm to 140 mm.This make a substantial increase in fatigue life of the drill pipe.To improve the impact toughness of the drill pipe body,the drill pipe body material is changed from Cr-Ni-Mo system to Cr-Mo-V system and the heat treatment is changed from oil quenching to water quenching.To improve the impact toughness of the tool joint,the tool joint furnace is upgraded to improve heating capacity.To improve the impact toughness of the weld zone,a new fuzzy control system of weld zone heat treatment is developed.The temperature accuracy of the system can be guaranteed within the±5℃to get a stable heat treatment quality.A new drill pipe straightness automatic detection devices and self-learning method of straightening are developed to achieve automated straightening.A welding process with high speed,single-stage pressure and high forging force is applied to inertia friction welding.A welding process with low speed,three-stage pressure and low forging force is applied to continous friction welding.     

Light Band Zone Formation and its Influence on Properties of Magnetically Impelled Arc Butt (MIAB) Welded Carbon Steel Tubes

Magnetically Impelled Arc Butt (MIAB) welding is a solid state welding process especially used in circumferential butt welding of tubes in which heat is generated prior to upsetting by an electric arc moving along the peripheral edges of the weldment with the aid of an external magnetic field. This paper aims at studying the formation of Light Band (LB) zone and its effect on the weld properties of MIAB welding of carbon steel tubes. A detailed microstructural analysis has been carried out to understand the microstructural transformations taking place in Thermo-Mechanically Affected Zone leading to formation of LB zone. Welded samples show better tensile properties with higher upset current as it eliminates LB zone formation at weld interface. For lower upset current, width of the LB zone increases with increase in arc rotation current resulting in lower weld tensile strength.     

钢轨闪光焊接头轨腰水平裂纹的原因分析

通过金相显微镜和电镜检验了钢轨接头轨腰水平裂纹的宏观和微观形貌,发现裂纹源区存在大量呈韧窝形貌的木纹状区域,并且发现裂纹由钢轨-侧向焊缝扩展,裂纹尖端止裂于焊缝,裂纹表面存在脱碳的现象,证实了裂纹产生于焊接的高温阶段,属焊接热裂纹。     

石油钻杆的摩擦焊接和焊缝热处理工艺研究

根据油田的使用经验,钻杆的失效主要体现在焊缝及内加厚过渡带两个部位.在提高焊缝的安全性方面,目前国内外各大钻杆生产厂主要是通过摩擦焊接方法及适当的焊缝热处理工艺来提高焊缝的安全系数.根据石油钻杆摩擦焊接及焊缝处理技术发展现状,结合API标准对石油钻杆焊缝力学性能的基本要求,对照中国石油天然气的行业标准,对宝钢生产的石油钻杆进行了部分焊缝力学性能统计,分析了宝钢石油钻杆的质量保证能力.为提高焊缝的安全系数,提出石油钻杆的摩擦焊接及焊缝热处理工艺的实现方法,并重点指出摩擦焊接与焊缝热处理工艺实现中应注意的问题.     

钽钢复合板钽覆层的焊接工艺研究

对钽钢复合板的钽覆层采用敷设盖板的方式焊接，研究了直流氩弧焊与交流脉冲氩弧焊两种焊接工艺对钽钢复合板焊接质量的影响。结果表明，直流氩弧焊的焊接热影响区较宽，焊接熔深为1～1．5mm，在钢与过渡金属层之间形成了中间夹层；交流脉冲氩弧焊的焊接热影响区较窄，焊接熔深为0．5～1mm，复合板焊接质量较好。与直流氩弧焊相比，交流脉冲氩弧焊焊接参数范围较宽，对焊工技能的要求相对较低，可实现连续化生产，因此更适合用于钽钢复合板钽覆层的焊接。     

连续退火机组焊机监控系统的改进设计

焊机是钢厂连续退火机组的关键设备之一，焊缝质量直接关系到机组产品的表面质量、通板能力和工作辊的辊耗。焊机监控系统是焊机的辅助系统，用于监控焊缝质量。宝钢某连续退火机组原有焊机监控系统是基于DOS的16位程序，而且不能在焊机旁直接观察监视焊缝温度等关系焊缝质量的曲线，这与连退机组领先的工艺水平和快节奏生产不协调。现对焊机监控系统进行了改进，完善了原有焊机监视系统的功能，使操作人员能及时了解机组的状态、焊接的质量，确保生产正常。在实际应用中获得了较好效果。     

Improving the reliability of welded joints in bulk-quenched electrosteel rail

Metallurgical methods of improving the reliability of the weld seam in bulk-quenched electrosteel rail are considered: optimization of the chemical composition in terms of the basic elements and total impurity content; improvement in plastic properties of the rail by reducing the hardness; and removal of nonmetallic inclusions from the steel. Instability is seen in the weldability of the rails and also in the composition, with the same set of mechanical properties. The need for improvement in welding technology is shown; without the elimination of existing problems, the weldability of electrosteel rail cannot be guaranteed.     

Influence of welding-flux moisture on welding quality

A high hydrogen content in weld produces hydrogen embrittlement,welding cold cracks,and even blowholes,which seriously affect joint performance and welding quality.Submerged-arc-welding flux has a great influence on the hydrogen content of the final weld.To simulate different flux storage circumstances and prewelding treatments,the effects of different welding-flux states on the welding quality and hydrogen content in weld were compared,using moisture content determination test and hydrogen content in deposited metal determination test.The test results reveal that to ensure the quality of welding,it is necessary to strictly control the storage of welding flux and procedures followed when using it.     

A study on weldability of zinc-coated steel sheets in lap joint configuration

The weldability of Zn-coated steel sheets 0.7 mm thick was investigated using resistance spot welding process. The effect of welding current, welding time and holding time on weld nugget characteristics, microstructure, and mechanical properties was discussed. Then, the possibility of replacing this welding process with laser beam welding was outlined. In this respect, quality of weld joints as a function of zinc removal by grinding prior to welding was evaluated. It is found that resistance spot welding current and time are the most significant parameters in affecting both expulsion and Zn-induced porosity. Expulsion was avoided and Zn-induced porosity was reduced with the decrease in welding current and/or welding time. Zn-induced porosity was completely eliminated by zinc-removal by grinding prior to welding. The best weld joint concerning nugget characteristics, soundness and tensile shear strength was obtained using welding current of 10 kA, weld cycle of 20, holding cycle of 18. Unlike resistance spot welds, high quality of CO₂ laser welds free from Zn-induced porosity could be made without zinc removal by grinding before welding.     

Energy-input-based finite-element process modeling of inertia welding

A coupled thermal and mechanical finite-element (FE) model has been developed to describe the inertia welding of RR1000 nickel-base superalloy tubes using the DEFORM 7.2 FE package. The energy input rate is derived from measurements of torque, angular rotation speed, and upset taken from actual inertia welding trials. The model predicts the thermal history of the joint as well as the deformation pattern and final residual stresses. The thermal variation has been validated by a microstructural study of the weld region of the trial joints. Thermal profile predictions have been made for three welds having the same initial kinetic rotational energy but different levels of flywheel inertia and rotational velocity. The concomitant residual stress predictions have been compared with nondestructive neutron diffraction residual stress measurements. The implications of the results for inertia welding are discussed.