0Cr16Ni5Mo厚板轧后开裂分析

分析了０Ｃｒ１６Ｎｉ５Ｍｏ厚板轧后开裂原因，其系轧后冷速过快所致。据此，采取了相应的有效措施，取得了满意的效果。     

船用吊杆0Cr16Ni5Mo不锈钢的焊接

概述了与0Cr16Ni5Mo马氏体不锈钢配套的焊接材料、焊后热处理制度以及适用的焊接工艺。试验选定采用M831A焊条,双U型坡口双面对称焊,焊后进行950℃/2h油淬+500℃/10h回火,得到的焊接接头性能完全达到指标要求。     

0Cr13Ni5Mo不锈钢电火花强化表面耐腐蚀性能研究

针对我国水轮机过流部件长时间运行后表面腐蚀严重这一问题,选用YG8电极材料对水轮机叶片用0Cr13Ni5Mo不锈钢进行电火花表面强化处理,基于电化学测试技术和交流阻抗测试方法,对强化层的电化学腐蚀性能进行了深入研究.结果表明,强化过程中电极材料与基体材料元素相互熔渗和扩散,强化层内有新的相结构生成,且强化层为冶金结合.与基体材料相比,在腐蚀溶液中电火花强化后试件的自腐蚀电位增大,自腐蚀电流密度减小,试件腐蚀速度变慢,耐腐蚀性能明显提高.     

回火温度对0Cr16Ni5Mo马氏体不锈钢组织和性能的影响

通过光学显微镜(OM)、扫描电镜(SEM)、X射线衍射分析(XRD)和力学性能测试,研究了回火温度对0Cr16Ni5Mo马氏体不锈钢组织和性能的影响。结果表明,试验钢在450—700℃温度区间回火处理后的组织均为回火马氏体+残余奥氏体+δ-铁素体,随着回火温度的升高,韧化相残余奥氏体含量先增加后降低,在600℃其含量达到最大值29.8%。其强度则随着回火温度的升高先降低然后回升,在600℃回火后强度最低,而伸长率变化趋势与强度相反;不同温度回火后的冲击断口均呈韧窝状,撕裂棱清晰可见,断裂方式均为韧性断裂。     

0Cr16Ni5Mo低碳马氏体不锈钢的热变形行为及其热加工图

在Gleeble-3800热模拟试验机上进行高温压缩实验,研究0Cr16Ni5Mo低碳马氏体不锈钢在变形温度为900~1150℃、应变速率为0.01~10s-1条件下的热变形行为。采用双曲正弦模型确定了该材料的热变形参数随应变量的变化规律,建立了相应的热变形本构方程。根据动态材料模型建立并分析了其热加工图,同时观察了变形组织。结果表明:在热压缩过程中,流变应力随变形温度的升高而降低,随应变速率的升高而增加,变形条件对材料的组织结构有较大影响。材料热变形参数与应变量之间可采用四次函数关系式表示,并且具有很好的相关性,获得了该材料的最佳热变形工艺参数范围为:变形温度980~1150℃,应变速率0.01~0.2s-1。     

0Cr13Ni5Mo/Q345C马氏体不锈钢复合板的焊接性

分析了 0Cr13Ni5Mo/Q345C马氏体不锈钢复合板的焊接性。通过抗裂性试验、复合板补焊及复合板对接焊、焊接工艺评定 ,提出了该复合板配套的焊接材料及可行的焊接工艺 ,按此工艺焊接的 0Cr13Ni5Mo/Q345C复合钢板接头的力学性能满足技术指标的要求。     

022Cr22Ni5Mo3N双相不锈钢的焊接

本文从焊接材料的选择、焊接的准备及焊接施焊过程等方面介绍了022Cr22Ni5Mo3N双相不锈铜的焊接情况,通过对焊接接头的焊后检验分析,证明此焊接工艺方案确实可行,对实际生产中022Cr22Ni5Mo3N双相不锈钢的焊接具有一定的指导意义。     

除氢处理对1Cr15Ni4Mo3N钢锻件疲劳性能的影响

研究了除氢处理对1Cr15Ni4Mo3N钢锻件疲劳性能的影响.1Cr15Ni4Mo3N钢锻造时可从加热气氛(油炉或天然气炉)中吸入氢,并导致锻件疲劳性能显著降低.结果表明:在淬火之前进行520℃×8h的除氢处理,可使1Cr15Ni4Mo3N钢锻件疲劳性能恢复至正常水平.     

316L不锈钢表面氮离子注入后的疲劳及腐蚀疲劳行为

３１６Ｌ（Ｆｅ－１７．５Ｃｒ１３．５Ｎｉ－２．５Ｍｏ）不锈钢注入Ｎ离子后，其自由腐蚀电位Ｅ＿０、孔蚀再钝化电位Ｅ＿ｐ及孔蚀电位Ｅ＿ｒ均大大提高。在大应变量下，疲劳寿命下降；在小应变量下，疲劳性能改善。在电位Ｅ＿０作用下，其腐蚀疲劳寿命较高子注入前有所降低。在施加电位Ｅ＿０－１００ｍＶ时，其疲劳寿命较离子注入前提高。表面离子注入层的存在提高材料的循环应力。     

金属橡胶用0Cr18Ni9Ti不锈钢丝疲劳断裂机理研究

运用扫描电镜和X射线衍射等技术，对金属橡胶的基体材料0Cr18Ni9Ti不锈钢丝做了金相观察分析，考察了冷拔变形量对不锈钢丝微观组织和力学性能的影响，分析了不锈钢丝动态加栽疲劳断口的形貌特征。实验结果表明：0Cr18Ni9Ti不锈钢丝经冷拔后内部存在大量孔洞，形变诱发大部分奥氏体组织发生了马氏体相变，使钢丝强度增大的同时降低了塑性；随冷拔变形量的增大，钢丝抗拉强度先增大后减小，延伸率持续减小；非金属夹杂物夹层以及孔洞存在的位置易形成应力集中，在循环应力作用下产生撕裂和孔洞累积，使断口呈现出木纹状断口或准解理-韧窝断裂的形貌特征。     

Fatigue and Corrosion Fatigue of High-Nitrogen Austenitic Stainless Steel

High nitrogen contents in solid solution as well as appropriate strengthening mechanisms in austenitic stainless steels can result in very high corrosion resistance. This is true in both air environment and in simulated human body fluids (corrosion fatigue). High cycle corrosion fatigue data are listed and compared with similar data for titanium base and cobalt base implant materials. Thus high nitrogen austenitic stainless steels are candidates to replace other stainless steels as implant materials.     

Fatigue Failure of 321 Stainless Steel Superheater Tubes from a Thermal Incinerator

Several boiler superheater tubes showed circumferential cracking at weld seams after 2 years in noncontinuous service (several shutdowns). On-site inspection revealed that several tubes were cracked and leaked; while many others were cracked, however, the severity was less pronounced. Two types of superheater tubes samples were collected: one with butt-welded tubes and the other with fillet-welded sleeve. The latter was found to be out of the boiler fireplace, and the sleeve was used as tubing support to the boiler shell. Detailed investigation showed that the butt-welded tubes contained circumferential fatigue cracks that initiated from the internal surface. The cracks initiated in the heat-affected zone and propagated as a result of tube vibration. The variations in the tube internal diameter and tube wall thickness are expected to play a role in tube fatigue failure. On the other hand, tubes with fillet-weld sleeve showed circumferential cracking as a result of fatigue crack initiation from weld defects on the tube external surface. The high vibration during several unscheduled shutdowns in addition to several other factors such as variations in tube inside diameter, wall thickness, and weld defects resulted in the initiation and propagation of fatigue cracks and premature failure. White deposits, similar to those observed when boiler tubes failed by caustic exposure, were seen in the vicinity of the tube cracks. Therefore, it was difficult to confirm whether the boiler tubes failed because of the fatigue cracks or because of the caustic salts (pH control chemical).     

Corrosion and Fatigue Testing of Microsized 304 Stainless Steel Beams Fabricated by Femtosecond Laser

The 304 stainless steel (SS) microcantilever specimens with dimensions of 30 μm×30 μm×50μm (thickness×width × length) were fabricated by femtosecond (fs) laser. The microsized cantilevers of good quality with structure and dimensions according commendably with that of the designed cantilever were obtained. The result shows that fs laser micromachining is a promising method for directly fabricating metallic microcomponents.Corrosion and fatigue properties of microsized specimens were carried out on the microsized 304 SS cantilever beams by a newly developed fatigue testing machine. The results show that the microsized 304 SS specimens appear to have an improved resistance towards localized corrosion compared to ordinary-sized 304 SS specimens after the static corrosion testing. The testing result shows that the presence of corrosive solution reduces the fatigue lifetime of the 304 SS specimen by a factor of 10-100. The maximum bending loads measured by fatigue testing machine decrease rapidly at the terminal stage of environment assisted fatigue testing.Corrosion fracture first occurred at the range of notch with a higher tensile bending stress, and exhibited clear evidence of trans-columnar fracture detected by SEM (scanning electron microscopy).     

0Cr13Ni4Mo钢的气蚀破坏微观分析

对０Ｃｒ１３Ｎｉ４Ｍｏ不锈钢在气蚀作用下的破坏形貌进行了微观分析。观察结果表明，其剥落形貌与冲击断口形貌心，剥落机制主要是韧窝和准解理的混合型。