40CrMo大截面锻材内裂探讨

对42CrMo大截面锻材的低倍检验,发现锻材的中心裂纹其实是白点,经采用去氢退火工艺后,白点消除,锻材探伤合格率、成材率明显提高。有电弧炉单炼,钢锭锻造由Φ250以睛的钢材时,去氢退火应是保证钢材内部质量的有效手段。     

CrMo钢φ180mm大锻材内裂产生及防止

采用联锻十缓冷工艺生产的φ１８０ｍｍ３５ＣｒＭｏ，４２ＣｒＭｏ锻材，经超声波探伤发现其内部普遍存在缺陷；大量的取样检验查明，这种缺陷是钢中气体引起的内裂纹，主要表现为锻材的中心裂纹及白点，采用控制锻后缓冷时间并及时进行去氢退火的方法，可以防止这些缺陷的产生。     

新产品40CrNi2MoA质量分析

40CrNi2MoA锻材的开发主要用于高速电力机的电机轴，在生产过程员部分锻材出现质量问题，本文对锻材的主要问题白点进行了详细分析，并提出防止白点产生的方法。     

大型环锻件白点成因分析及解决办法

本文针对连铸圆坯辗环后出现白点问题,从环锻件生产工艺、圆坯的纯净度及低倍组织进行分析,认为在现有氢含量≤2 ppm条件下,环锻加工工艺、冷却工艺以及钢中的夹杂物是白点产生的主要原因。     

3Cr2W8V大截面锻材热处理工艺探讨

经酸浸低倍和金相组织检验及超声波探伤,证明大锭型存在链状亚稳定共晶碳化物组织,这种组织是构成钢材内裂的裂纹源。大截面锻材还存在“白点”问题。通过适当加钛和稀土合金,保证锻造前加热透烧,加大横向锻比等,可改善碳化物分布。通过锻后回炉再烧 出炉后在Ar1附近温度快冷 扩氢处理,可熔断链状碳化物,防止二次网状碳化物析出,可消除“白点”缺陷,钢材缺陷呈点状分布,缺陷当量满足技术要求。     

3Cr2W8V大截面锻材热处理工艺探讨

经酸浸低倍和金相组织检验及超声波探伤，证明大锭型存在链状亚稳定共晶碳化物组织。这种组织是构成钢材内裂的裂纹源。大截面锻材还存在“白点”问题。通过适当加钛和稀土合金，保证锻造前加热透烧，加大横向锻比等，可改善碳化物分布。通过锻后回炉再烧 出炉后在Ar1附近温度快冷 扩氢处理。可熔断链状碳化物，防止二次网状碳化物析出，可消除“白点”缺陷，钢材缺陷呈点状分布，缺陷当量满足技术要求。     

合结钢锻件产生白点原因分析及预防措施探讨

根据锻件白点形成原因，结合实际生产情况，提出预防产生白点的措施有制订严格的冶炼工艺，科学的锻造成型工艺及合理的锻后冷却制度。     

锻材锻件形成白点原因分析及预防

本文根据锻件白点形成的原因，就锻年生产的实际情况，提出了几项预防白点的措施；合理的浇注温度和浇注速度，锻后保温处理，增大锻比及材质的选择。     

合工钢CrWMn工艺技术优化

合工钢CrWMm主要用于制作量具、刃具，在锻材中易产生白点，经研究表明，通过工艺路线的改进。主要通过热处理攻关，白点问题得到有效控制。     

合工钢CrWMn工艺技术优化

合工钢CrWMn主要用于制作量具、刃具，在锻材中易产生白点，经研究表明，通过工艺路线的改进，主要通过热处理攻关，白点问题得到了有效控制。     

钢中的白点的检验

提出了检验白点时应区分不可逆氢脆白点和可逆氢脆白点，讨论了不可逆氮脆白点和发裂的关系，对检验白蹼的各种方法进行了评论。     

白点缺陷预防方法

白点是钢材中决不允许存在的缺陷,通过研究生产实际情况,总结“白点”出现的规律,分析了生产过程氢含量的变化,提出防止“白点”缺陷产生的方法,对实际生产有很好的指导作用。     

钢锻件超声检测缺陷定性分析研究

 采用TS-2008C数字式超声探伤仪研究了45号碳素钢锻件中部分典型缺陷的波形曲线规律,在试验车间进行了45号碳素钢人工模拟缺陷试块的制作,研究了白点、裂纹、夹杂物等几个典型的缺陷通过A型脉冲反射式超声检测时的回波曲线特性,对缺陷回波曲线特征进行了定性分析。研究结果表明,通过对已知缺陷回波曲线及包络线等电子信号的分析,对白点、中心锻造裂纹、横向内裂纹、纵向内裂纹、单个夹渣和分散性夹杂物等缺陷进行超声检测时回波曲线匀具有各自的特征,通过观察曲线特征及对检测过程的动态描述可以初步对缺陷类型进行定性。     

On the problem of hydrogen removal during heat treatment of large forgings

The solutions to a differential equation for the problem of heating of a cylinder in a medium with a fixed temperature are used to obtain equations for estimating the change in the hydrogen concentration in forgings from data on the hydrogen concentration at the cylinder axis or on the average bulk hydrogen concentration. Similar equations are also obtained for forgings having square cross sections. The calculation demonstrates that, for the case of a twofold decrease in the hydrogen concentration in a forging, the calculated times of annealing of a cylindrical forging differ by three times.     

Classifying internal defects in forgings based on flaw-detection patterns obtained by ultrasound

A method has been proposed for classifying internal defects in forgings based on the flaw-detection patterns obtained in ultrasonic testing. The reliability of the method is greater than 75%. Also, a program has been developed to classify internal defects in relation to their length and their location through the thickness and width of forgings. The method is valid for flaw-detection patterns in groups I and III. The method is now being used at the Chelyabinsk affiliate of the Ural Forging Company. The method of classification can also be used to identify internal defects in cylindrical specimens obtained by free forging on presses.     

7075模锻件心部裂纹原因分析

7075模锻件横截面断口上有白色带状缺陷，表现形式为紊流状和小裂纹，这是心部强烈变形区组织薄弱点被拉断所致。产生裂纹与锻造温度不当和两次锻造变形量分配不合理有关。为了消除锻件心部裂纹，应控制好铸锭加热温度，合理分配两次锻造变形量。     

堆冷方式下板坯氢扩散效果

 为了考察某中厚板厂板坯堆冷工艺过程中氢元素的去除效果，最终达到防止白点、提高探伤合格率的目的，依据菲克第二定律非稳态传质方程，以8块断面为250 mm×1 600 mm板坯为研究对象，利用有限元软件ABAQUS建立了中厚板铸坯堆冷过程二维氢扩散模型。计算结果表明,利用相变时的除氢峰效应，对连铸坯进行堆冷是一个很有力的除氢措施。在堆冷条件合理的情况下，下线连铸坯在堆冷24～48 h后除氢率高达84.6%。如果以平均w(H)等于0.000 1%为防止产生“白点”的判断标准，则堆冷24 h后可认为铸坯w(H)已处于安全范围；如果以最大w(H)等于0.000 1% 为防止产生“白点”的判断标准，则堆垛36 h后认为铸坯w(H)已完全处于安全范围。     

Sulfides in forgings of 40KhGM structural steel

Sulfides in large forgings of 40KhGM steel containing from 0.005 to 0.023% sulfur are studied by optical and scanning electron microscopy (on fracture surfaces and polished sections) and by transmission diffraction electron microscopy (on thin foils). Several types of sulfides are found to exist in the forgings, depending on the sulfur content. Globular sulfides exist at all sulfur contents. They are located inside grains in contact with aluminum, magnesium, and silicon oxides or titanium nitride and carbide particles, which serve as substrates during sulfide solidification. At a low sulfur content, faceted manganese sulfides form in the steel; they are not in contact with oxides and are located inside grains. At 0.013–0.023% sulfur, elongated eutectic sulfides, which are located near or at the boundaries of primary grains, appear. The data obtained suggest gaps between sulfides and the matrix, and these gaps can play the role of “hydrogen traps.”