轧制工艺对气瓶钢板示波冲击性能的影响

应用示波冲击试验测量了不同终轧温度下HP295钢板在系列温度下的冲击韧性，测量了冲击断口试样的横向扩张量，利用扫描电镜分析了示波冲击断口形貌，结果表明，终轧温度提高，钢的韧脆转变温度提高，钢的冲击韧性下降，裂纹扩展功下降，示波冲击温度越低，终轧温度对韧性的影响越显著，冲击韧性与冲击断口的横向扩张量和断口的形貌具有较好的对应关系。     

2.25Cr-1Mo钢低温冲击性能和韧脆转变温度研究

对2.25Cr-1Mo钢进行了系列温度的夏比V型缺口冲击试验,通过冲击吸收能量和断口形貌研究了其低温冲击韧性和韧脆转变温度。结果表明,该钢管在高于-30℃温度时呈韧性断裂或韧脆性混合断裂,低于-30℃呈解理脆性断裂。其韧脆转变温度为-23.9℃。     

高强度钢韧化机制及与亚结构关系的研究

摘要：以实际生产制备的800MPa级调质态水电钢为研究对象,结合扫描电子显微镜（SEM）、电子背散射衍射（EBSD）和冲击实验等,利用显微组织晶体学结构可视化与定量化方法,研究了钢板厚度方向不同取样位置低温韧性差异的本质原因。结果表明,高强度中厚板厚度方向由表面向心部过渡,显微组织由板条状贝氏体向粒状贝氏体过渡,低温冲击韧性降低,韧脆转变温度（DBTT）升高。随显微组织由表面向心部过渡（冷速降低）,变体选择加强,心部形成了以单一贝恩（Bain）组为主导的相变组织,大角度晶界密度显著降低,且韧脆转变温度的升高与block界面密度降低紧密相关。此外,研究发现奥氏体晶粒内部的block界面和奥氏体晶界可以有效地偏折和阻止裂纹扩展,但由于奥氏体界面密度显著低于block界面,故对冲击实验过程中裂纹扩展阻力的贡献主要来自晶内的block界面。     

V150钢级钻杆管体用无缝钢管的性能研究

文章对包钢研制生产的V150钢级钻杆管体用无缝钢管的拉伸、冲击、韧脆转变温度、室温抗扭强度、旋转弯曲疲劳等性能进行了试验研究,结果表明:热处理态钢管的常规力学性能、晶粒度等技术指标可满足DS—1 TM标准第1卷《钻井用管材产品规范》的要求,同时还具有横向冲击韧性好、低温冲击韧性高、韧脆转变温度低、室温抗扭强度大、抗旋转弯曲疲劳性好等优良的材料特性,可满足V150钢级超高强度钻杆管体用钢的要求.     

低碳钢魏氏组织的形貌特征及其对机械性能的影响

测定了S15A钢经同一温度奥氏体化不同速度冷却处理后的冲击韧性。有魏氏组织的试样较呈等轴铁素体的试样有更高的冲击韧性和更低的韧脆转变温度。 用光学显微镜,透射电子显微镜,扫描电子显微镜,图象分析仪等手段研究了S15A钢魏氏组织的形貌、针状铁素体的精细结构、冲击断口形貌、裂纹的萌生及扩展和受阻。 分析了魏氏组织提高低碳钢机械性能的原因。     

锻后加热正火对35MnVN钢组织和性能的影响

本文考察了锻后正火对35MnVN钢显微组织和机械性能的影响;通过系列示波冲击试验和定量金相方法,分析探讨了影响冲击韧性的微观因素以及冲击断裂机制。结果表明:加热温度不超过1000℃的正火处理可以细化纲的组织,增加先析铁素体含量,从而在保证较高强度水平的同时,提高冲击韧性,降低韧脆转变温度,先共析铁素体含量为冲击韧性的主要影响因素。随着原始奥氏体晶粒的粗化和先析铁素体含量的减少,断裂机制由应变诱导准解理断裂变为应力诱导解理断裂;冲击功由受裂纹扩展功控制变为受裂纹形成功控制。     

固溶温度对Cr-Co-Mo-Ni轴承钢低温韧性的影响

通过对韧-脆转变温度及冲击断口的韧-脆断裂转变趋势的分析,研究了Cr-Co-Mo-Ni轴承钢经不同温度固溶热处理后的韧-脆转变温度及其影响因素。结果表明:在1 000、1 030和1 060℃固溶,其韧-脆转变温度为100℃以上,在1 090℃固溶,韧-脆转变温度为70℃,且在-50℃钢的冲击功能保持在47J以上,1 120℃固溶,韧-脆转变温度为52℃,且-50℃的冲击功为46J以上。随固溶温度的增加,原始晶粒增大,韧-脆转变温度却降低,这是晶界处大颗粒M6C碳化物导致。     

试验温度对船用Ti-70钛合金板材冲击韧性的影响

本文通过测试10.0mm Ti-70钛合金板材不同温度的冲击韧性,观测冲击断口形貌,研究了Ti-70钛合金板材冲击韧性与温度的关系,分析了不同温度下Ti-70钛合金板材的断裂方式。结果表明,25℃~-120℃随着温度降低,Ti70板材冲击功逐渐降低,但无明显韧脆转变现象。随冲击温度降低,断口脆性断面率逐渐上升,不同温度下冲击断口均为准解理断裂。     

煤矿冻结施工用钢试验研究

为了提高煤矿冻结施工用钢的低温冲击性能,研究采用低碳微合金化成分设计、正火热处理工艺并利用Origin软件确定不同合金成分热轧态和正火态的韧脆转变温度。结果表明,适当降低碳含量,添加V、Ti合金、降低磷硫含量,可有效提高煤矿冻结施工用钢的低温冲击韧性,降低其韧脆转变温度。     

X80级管线钢热影响区的局部脆化

研究了国产X80级管线钢热影响区的冲击韧性和组织的局部脆化.结果表明,该钢的焊接热影响区的冲击韧性较母材降低50%以上;在所研究的20～-40 ℃温度区间内,其断口的宏观形貌特征从部分脆性特征转变为完全的脆性断口;20 ℃放射区断口呈现韧性断裂和解理断裂共存的混合型断口,并且试验温度为20 ℃和0 ℃时,分别在放射区和纤维区可观察到微观裂纹;热影响区断口表层剖面组织为粒状贝氏体,显示出粗晶区的特征.裂纹扩展方向为沿晶界扩展,粒状贝氏体中M/A岛尺寸增大,并存在裂纹穿过岛状物的现象,这是晶界严重脆化的结果.     

Fracture of high-nitrogen 05Kh20G10N3AMF steel during impact loading

Specimens with V- and U-shaped notches made of austenitic high-nitrogen corrosion-resistant 05Kh20G10N3AMF steel are subjected to impact tests in the temperature range from +20 to ?196°C, and stress-strain diagrams are recorded. The test data are used to estimate impact toughness KCV and KCU, dynamic fracture toughness J _id at the stage of crack nucleation, and crack propagation energy A _p. The microrelief of the fracture surfaces is studied. As compared to forging, quenching from 1100°C is found to increase the impact toughness and the dynamic cracking resistance of the steel during impact loading and to decrease the ductile-brittle transition temperature. The steel is shown to exhibit the cold brittleness behavior characteristic of bcc materials. A model is proposed for the formation of cleavage facets in austenitic steels. It is based on easy slip along lattice planes under the low shear stress at a notch tip and the development of fracture at a stress lower than the yield strength of the material.     

风电塔筒法兰用S355NL钢的低温冲击韧性

试验和分析了风电塔筒法兰S355NL钢（/%:0.14C,0.22Si,1.35Mn,0.010P,0.002S,0.06Cr,0.01Mo,0.10Ni,0.03Cu,0.40Ceq）-20~-80℃切向和轴向冲击韧性。结果表明,S355NL钢V-型冲击功随试验温度降低而下降,切向试样的韧脆转变温度低于-80℃（-80℃平均冲击功76.89 J）,轴向试样的韧脆转变温度在-65℃左右（-60℃平均冲击功96.10 J,-70℃13.28 J）,冲击断口形貌由韧性剪切断口转变为准解理断口,直至具有"扇形"解理花样的完全解理断口。     

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.     

Fracture process of a low carbon low alloy steel relevant to charpy toughness at ductile-brittle fracture transition region

The fracture process that determines the Charpy energy at the ductile-brittle transition region was investigated by means of the instrumented Charpy test and fractographic analysis with a low carbon low alloy steel subjected to different control-rolling conditions. The decomposition of a Charpy energy into the energies dissipated in the course of the notch-tip blunting, stable crack growth, and brittle crack propagation is unique irrespective of the testing temperatures and specimen series. Toughness level can be divided into four regions according to the pre-dominating fracture process. The temperature dependence of toughness and effects of the an-isotropy of a specimen originates in the brittle fracture initiation stage rather than the resistance against the notch-tip blunting or stable crack growth. From fractographic examination referring to the stress analyses, it is discussed that the brittle fracture initiation is controlled by the local deformation microstructures in the plastic zone together with the stress field ahead of the notch or the stable crack front. Formerly Graduate Student, Department of Materials Science and Engineering, Waseda University     

-70 ℃超低温环境用钢09MnNiDR的组织性能

 09MnNiDR作为-70 ℃超低温环境钢,少镍低成本属性引起了广泛的关注,细化铁素体晶粒和球化渗碳体为其提高低温冲击韧性的主要方法。为了探究微观组织对其综合力学性能的影响,采用3种不同热处理工艺对09MnNiDR钢进行了试验,利用光学显微镜、扫描显微镜、拉伸试验机和低温冲击韧性试验机对试验钢的微观组织形貌进行了观察和力学性能的测定。结果表明,试验钢经正火后晶粒得到了细化,铁素体晶粒度为13级,-70 ℃低温冲击韧性不小于25 J,韧脆转变温度为-70～-80 ℃;试验钢正火加热保温出炉后采用风冷加速冷却能进一步细化晶粒,铁素体晶粒度达到14级,强度和韧性同时得到了提高,韧脆转变温度降低至-80～-90 ℃;试验钢经正火+回火处理后,正火形成的片状或短棒状渗碳体在回火时发生了球化转变为颗粒状,对比正火态强度出现了下降,低温冲击韧性得到了进一步的提高,韧脆转变温度降低至-100 ℃以下。不同的生产企业可以选择合适的热处理工艺来提高09MnNiDR的低温冲击韧性,满足用户的特殊需求。     

硅对铁素体耐热不锈钢韧脆转变行为的影响

铁素体耐热不锈钢18Cr-Al-Si具有优良的导热性能及良好的耐高温气体腐蚀性能,同时复合添加铝和硅元素又确保了其具有优异的抗高温氧化性,该钢是应用于超(超)临界电站锅炉连接件的一种新型耐热钢材料。以往,对于连接件材料的加工主要采用传统的水切割加工成型方法,但生产效率较低且成本较高;采用室温冲压加工成型的方法时,由于该类铁素体耐热不锈钢板脆性较大,容易在钢板厚度中心处产生裂纹;而采用带温冲压加工(即在韧性温度区间加工)时,则可避免钢板中心开裂的问题。为了提高连接件材料的生产效率,需要优化和确定该钢带温加工工艺参数。采用系列温度夏比冲击试验方法并借助扫描电子显微镜(SEM)、透射电子显微镜(TEM)及能谱仪(EDS),研究了硅含量(质量分数为0%～0.9%)对18Cr-Al-Si钢韧脆转变行为的影响。结果表明,随着硅含量的增加,各试验温度下的冲击吸收功逐渐降低、韧脆转变温度(DBTT)升高、微观断口中解理面数量增多、韧窝面积逐渐减少。硅元素对退火后的18Cr-Al-Si钢微观组织及析出物影响较大,随着硅含量的增加,钢中铁素体晶粒尺寸逐渐增加,M₂₃C₆     

Effect of Post Weld Heat Treatment on Toughness of Base Metal of Nuclear Reactor Pressure Vessel Steel A533B

The effect of post weld heat treatment (PWHT) on the toughness of nuclear reactor pressure vessel steel was investigated.Fracture toughness (K JC) and Charpy impact toughness (KVC) were obtained at different temperatures for quenched-tempered (QT) and PWHT A533B steel plates,respectively.The results show that PWHT increases the ductile-brittle transition temperature,and decreases the K JC and KVC.By using SEM and Electron probe micro-analyzer (EPMA),it is found that the size of the precipitation phases increased and molybdenum precipitated during PWHT respectively.The relationship between the size of the precipitation phases and the fracture toughness are analyzed and the influence of microstructure is also briefly discussed.     

550 MPa级海洋工程用钢板低温韧性波动原因分析

 550 MPa级海洋工程用钢在低温冲击功波动较大。为了进一步探究产生低温韧性波动的原因,在不同温度(-100 ℃~室温)对试验钢进行冲击试验。结合光学显微镜、扫描电子显微镜、透射电镜等设备,分析冲击断口、显微组织、第二相、夹杂物。结合热力学计算等对低温韧性波动原因进行分析讨论。结果表明,试验钢强度满足等级要求,随着温度降低冲击吸收功不断降低,韧脆转变温度为-50 ℃左右。在-60 ℃下冲击功出现较大波动,出现了18 J的极低值,断口为准解理断裂,剪切断面率为8%,裂纹源处存在Ti,Nb(C,N)和MnS的复合夹杂。而在相同温度下冲击功为122 J的试验钢,剪切断面率为34%,断口发现有明显的韧窝。试验钢组织主要为回火贝氏体加极少量铁素体,贝氏体板条中存在高密度位错,晶界上有(Fe,Cr)₃C合金渗碳体与少量NbC和富Cu析出相。试验钢以小角度晶界为主,大角度晶界占比较低。基体中有少量(Ca,Al,Mg,Mn,S)等复合夹杂物,多呈近圆形和多边形,大小多为1~3 μm,占检测到的总数量的85.87%。占比例最高的是CaS-Oxide-MnS类夹杂,为31.2%。热力学计算结果表明试验钢凝固过程中TiN先于MnS析出。晶界与晶内粗大的析出相、夹杂物、较高比例的小角度晶界与塞积的不可动位错等多种因素对低温冲击韧性产生不利影响,存在大颗粒含钛析出相是造成冲击韧性波动大的关键原因。     

Normalization of the Cold Shortness of Plate Steel: II. Short-Brittleness Thresholds in Pipe Tests

The following serial curves are obtained for a pipe steel of strength class K65 (Kh80): strength and plasticity curves during tension in the temperature range from–80 to +20°C, fracture energy from drop weight tear test (DWTT) diagrams, and impact toughness KCV curves (from–180 to +20°C). The ductile–brittle transition temperature range determined from the DWTT energy is shown to be higher than that determined from a KCV diagram by 80 K. The KCV^–40 criterion is concluded to be more reliable than the DWTT^–20 criterion. KCV and DWTT tests are shown to reproduce the crack starting conditions in a pipe, and the resistance of a high-strength pipe steel to extended fracture should be estimated using other criteria.