避免40CrMnMo钢在Ucon—A淬火液中淬裂的措施

我厂生产的石油打捞工具,大壁厚的长筒形零件很多,材料为40CrMnMo,要求(?)处理。热处理采用油淬,力学性能达不到关于石油机械的SY5200-87标准的要求(σ_b>970MPa,σ_s>760MPa,δ>13％,ψ>45％,σ_k>54J/cm~2),水淬又易淬裂。近年来采用Uoon-A水溶性淬火介质,在力学性能上基本能够满足要求,但淬裂情况比较严重,经分析发现淬裂与否的关键在于冷却速度和冷却时间的控制。 1.冷却速度的控制 众所周知,Ucon-A这种水溶性淬火介质与水混合,根据其浓度的不同,其冷却速度在水和中速淬     

大型电铲辊道的水—空间歇淬火

本文通过对水冷，空冷，喷雾冷却，水－空间歇冷却的冷却介质特性的比较，总结出水－空间歇冷却是替代油冷的一种较好方式，并且通过对电铲辊道进行水－空间歇淬火的试生产，验证了生产为４３４０Ｈ钢锻件的水－空间歇淬火后的性能与油淬后的性能基本相当或略高于油冷。     

CL-有机淬火介质

机械零件在淬火过程中,经常出现变形、开裂、全相组织不合格和硬度不符合要求等缺陷。其原因除与钢材成分、原始组织状态、工件尺寸及形状、加热规范等因素有关外,还与淬火介质的冷却特性有极大的关系。水和油是常用的淬火介质,但它们的冷却特性往往不能满足某些工件的淬火要求。西安石油化工厂研制成功了CL-1有机淬火介质,通过实际应用,表明是一种理想的淬火介质。     

水溶性淬火介质冷却特性控制及应用

热处理过程主要由加热和冷却两部分组成,产品的状态一旦确定,冷却介质在冷却过程中将起着决定性的作用。传统淬火介质主要是水和油,随着机械产品对力学性能要求的不断提升,传统淬火介质的冷却特性已无     

油淬Ni_(64)Al_(36)合金的逆马氏体相变

用内耗试验、差示扫描量热和X射线衍射分析等方法对油淬和炉冷的Ni64Al36(原子分数)合金从室温到400℃的逆马氏体相变过程进行了研究。结果表明:在加热过程中油淬Ni64Al36合金在220℃出现一个内耗峰,冷却时内耗峰的温度移到160℃,而炉冷Ni64Al36合金无内耗峰出现;油淬Ni64Al36合金的内耗峰峰位不随振动频率而变化,但峰高随频率的减小和升温速率的提高而增大;油淬Ni64Al36合金在冷却和加热时出现的两个内耗峰分别是由γ→L10马氏体转变及其逆马氏体转变引起的;在室温到400℃有限次数热循环范围内,热循环次数对油淬Ni64Al36合金正、逆马氏体转变的影响很小。     

搅拌转速对渗碳17CrNiMo6钢在硝酸盐浴分级淬火时畸变的影响

采用冷却性能测试仪测试了不同搅拌转速下硝酸盐介质的冷却特性曲线,分析了搅拌转速对该介质冷却能力的影响;在17CrNiMo6钢棒上加工出C形试样并进行了渗碳处理,然后分别进行了不同搅拌转速下的硝酸盐浴分级淬火和油淬,分析了搅拌转速和淬火介质对该试样畸变的影响。结果表明:搅拌转速对硝酸盐介质低温冷却速率的影响最为显著;随着搅拌转速的增大,经硝酸盐浴分级淬火后试样的平均畸变率增大,搅拌转速为300r·min-1时的平均畸变率最小,为1.66%,比快速淬火油淬火后的(2.33%)降低了28.8%;搅拌转速为700r·min-1时更有利于控制硝酸盐浴分级淬火时试样的畸变量,该速度下的畸变量测试值的均方差最小,平均畸变率为1.84%。     

PAG淬火介质在合金结构钢前轴余热淬火中的应用

淬火介质对保证淬火工艺实施有重要作用。采用水或油作为淬火介质,均存在一定缺陷,不能满足合金结构钢前轴锻件热处理的需要。通过分析理想淬火介质的冷却曲线,发现一种新型PAG淬火介质的冷却特性可以满足要求。介绍了这种新型淬火介质的冷却原理、使用条件及技术要点。并结合实践,介绍了该介质在合金结构钢前轴锻件(42CrMo材质中重型前轴,120~140kg)热处理生产过程中的使用情况。     

DJ4机车螺旋弹簧用钢——51CrV4热处理工艺优化

在淬火温度不变情况下,通过调整DJ4机车螺旋弹簧用钢——51CrV4的回火温度及冷却介质,比较其各项力学性能指标,获得优化的热处理工艺为:860℃油淬——480℃回火——空冷。     

超大锻件淬火冷却模式数值分析

根据大容器饱和水沸腾传热机理,结合工件淬火冷却过程的淬冷沸腾传热特征,分析喷水、浸水循环搅拌、浸水静止三种模式下水冷淬火表面的传热系数.通过建立数学模型,对三种模式下核电筒节类大锻件(16MnD)的淬火冷却过程进行数值分析,得到工件温度的分布特征.分析结果表明,在淬冷沸腾阶段由于传热系数较高,在喷水、浸水循环搅拌、浸水...     

梯形螺纹塞规的热处理

T8钢制梯形螺纹塞规的热处理工艺,我厂过去采用780～800℃加热后进行水淬油冷的做法,淬火后经常发现梯形螺纹部分产生裂纹而使塞规报废。分析其原因是截面不均,淬火后应力较大不能及时消除造成的。为了解决上述矛盾,我们采用以下的淬火介质进行等温淬火,使塞规高温时冷却速度快,低温(马氏体转变)时冷却速度慢,从而避免了低温转变     

Effect of Heat Sink and Cooling Mediums on Ferrite Austenite Ratio and Distortion in Laser Welding of Duplex Stainless Steel 2205

In order to control the ferrite and austenite percentage in duplex stainless steel welding, many researchers try to change the laser welding parameters and cooling medium, but ignore to study the influence of heat sink e ect on weld strength. In this work, the e ect of aluminium heat sink and varying cooling medium on the laser welding of duplex stainless steel(DSS) 2205 is studied. The 2 mm thick DSS sheets welded with pulsed Nd: YAG laser welding machine by varying the cooling medium(air and oil) and an aluminium plate used as a heat sink. The welded specimens tested for tensile strength, micro-hardness, distortion, microstructure and radiography analysis. The faster cooling rate in the oil quenching process enhances the ferrite percentage compared with air-cooled samples. But the faster cooling rate in oil quenching leads to more distortion and using aluminium as a heat sink influenced positively the distortion to a small extent. The lower cooling rate in air quenching leads to a higher tensile strength of the welded specimen. The objective of this work is to analyse experimentally the e ect of cooling medium and heat sink in the mechanical and metallurgical properties of laser welded duplex stainless steel.     

轴流风机油路长周期运行的实现

针对轴流风机在使用过程中油路严重腐蚀,风机长周期运行受到影响的问题,从腐蚀机理和油路工作环境出发,分析了风机油路腐蚀的原因,得出湿热水汽和干湿交替的大气环境导致油路腐蚀的结论。经过探索,实现了风机油路的长周期运行。     

太阳能砷化镓电池与导热油的光热转换实验

为提高聚光时太阳能砷化镓电池的效率,利用导热油作为换热介质,将砷化镓电池的聚光温度冷却,温度升高后的导热油把热量传给低沸点工质,促使工质汽化并进入膨胀机做功。对三种不同冷却方式下砷化镓电池的效率进行了实验对比,结果表明:以导热油为介质的冷却方式,与水冷和风冷相比,砷化镓电池的平均温度分别降低了5.75℃和40.04℃,其平均效率分别提高了1.83%和11.96%。     

Design of an energy saving oil cooler system using hot gas

According to the development of machine tools to higher speed and multi axes, thermal error which is known to account for about 70% of the total error of machine tools is becoming a serious issue. To reduce thermal error, the heat generating parts of machine tools are cooled down by direct contact with a cooling medium. The medium in most cases is oil, thus, the cooling device is called oil cooler. In this study, an oil cooler system employing hot gas bypass method was developed to improve the performance including energy efficiency of the oil coolers used for ultra-precision machine tools. Through tests, the developed system exhibited high temperature control accuracy of ±0.1°C, and less energy consumption than conventional on/off type (equipped with heater for preventing excessive cooling) by about 45%. The proposed oil cooler system is applicable to semiconductor process, ultra-precision injection molds, as well as ultra-precision machine tools to improve product quality and energy efficiency of production facilities.     

绿色切削SiCp／Al复合材料的刀具温度研究

采用嵌埋人工热电偶的方法,通过正交试验研究了干切削SiCp／Al复合材料时切削参数对刀具前、后刀面切削温度的影响。选定切削参数,实验研究了干式切削、压缩空气风冷、油液浇注和MQL等冷却方式对前、后刀面切削温度的影响。试验结果表明,对于车削SiCp／Al复合材料,后刀面温度高于前刀面温度,进给量对刀具温度影响最显著,MQL切削条件下刀具温度最低。     

Experimental investigation of surface quality for minimum quantity oil–water lubrication grinding

Effective lubrication and cooling is necessary to ensure grinding temperature levels not to become excessive during grinding process. Conventional grinding fluid has negative influences on the working environment in terms of the health of the machine operator. Furthermore, the using of grinding fluid is seen to increase production cost due to fluid purchase and disposal. One attractive alternative is the minimum quantity lubrication (MQL) grinding. In this study, oil–water was applied in the MQL grinding and the grinding results were compared with those of wet, dry, and pure oil MQL grinding. It is found that MQL grinding in comparison to dry grinding significantly enhances grinding performance in terms of improving the quality of the ground workpiece and reducing grinding temperature and forces. Compared with pure oil MQL grinding, the grinding temperature and the thickness of the affected layer for oil–water MQL grinding are lower. However, the tangential force and surface roughness for oil–water MQL grinding are higher than that for pure oil MQL grinding. This indicates that the former has a better cooling condition than the latter, but the lubrication capacity is contrary.     

表面换热系数对铝厚板淬火温度和应力演变影响的数值模拟

淬火过程中表面换热系数是反映界面能量传递和介质冷却能力的重要物理参数.通过对铝厚板淬火的多组模拟实验,研究了表面换热系数对工件冷却速度、内应力演变的影响规律.结果表明,过大的表面换热系数并不能明显提高工件心部的冷却速度,却大大增加了工件的残余应力.铝厚板淬火工艺应根据工件的组织性能要求,合理选择表面换热系数和冷却方式,尽量减小工件的残余应力.     

Phase transformation-based finite element modeling to predict strength and deformation of press-hardened tubular automotive part

In this paper, a new tool design for hot stamping taking advantage of both direct quenching and indirect die quenching is proposed to fabricate the coupled torsion beam axle which is formed from the original tubular-shaped part. This newly proposed hot stamping applies spray of the water before the upper die gets into contact with the tubular part, which significantly enhances the cooling capacity. For other region that cannot be covered by the direct spray, the conventional die quenching method in direct hot stamping process is used. Moreover, for the analysis of the deformation behavior during the proposed hot stamping process, the finite element analysis, which takes the deformation and strengthening induced by the cooling and phase transformation into account, has been carried out. From the analysis, the larger shape change when the cooling time is shorter than 15 s could be explained by the incomplete martensitic phase transformation and phase transformation plastic strain. When the cooling time is short the residual stress after cooling is much higher than those for the longer cooling times.     

三种雾化气体淬火设备的方案设计与分析

采用水基或油基作为淬火介质进行淬火后,淬火工件均存在一定的缺陷,有些甚至不能满足生产需要。通过分析理想淬火介质的冷却曲线发现,以雾化气体作为淬火介质,即采用气液两相流进行淬火,冷却特性十分接近理想介质的冷却曲线。本文针对雾化气体淬火试验,设计了3种雾化气体淬火设备实施方案,井对其进行了对比性研究,找出最佳方案,从而得出了设计雾化气体淬火设备时应该特别注意的几个问题,为今后的设计及改进工作提供了理论依据。     

工程车辆散热调温控制系统

分析介绍工程车辆上的独立风扇结构的散热调温系统,为该系统设计了转速、温度双闭环控制结构的调温控制器,为了对发动机水温、液压油温、变矩器油温控制,引入温度优先法则.该控制系统使得发动机、液力、液压系统工作在正常的温度.