淮阴工学院材料力学性能考试重点

淮阴工学院材料力学性能考试重点 facilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and 第一章 金属在单向静拉伸载荷下的力学性能 名词解释 弹性比功: 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 示材料吸收弹性变形功的能力，一般用开始塑性变形前单位体积吸收的最大弹性变形功表示。 包申格效应:金属材料经过预先加载产生少量塑性变形，卸载后若再次同向加载，则规定残余伸长应力增加，反之若反向加载，则规定残余伸长应力降低，此类现象称为包申格效应。 滞弹性 在弹性范围内快速加载或卸载后，随时间延长产生附加弹性应变的现象，称为滞弹性。 循环韧性 材料吸收不可逆变形功的能力称为循环韧性。 屈服平台 屈服伸长对应的水平线段或曲折线段称为屈服平台或者屈服齿 吕德斯带 屈服伸长变形是不均匀的，外力从上屈服点下降到下屈服点时，在试样局部区域开始形成与拉伸轴约呈45?的屈服线，称为吕德斯带。 应变硬化 金属变形过程中，当外力超过屈服强度后，需要不断增加外力塑性变形才能继续进行，这种现象就叫应变硬化。 dSS,颈缩判据 de 静力韧度 金属材料断裂前吸收塑性变形功和断裂功的能力 穿晶断裂和沿晶断裂:多晶材料断裂时裂纹扩展路径若沿着晶界，则为沿晶断裂;若裂纹扩展穿过晶粒，则为穿晶断裂。 解里刻面 解理断口由一系列的相当于晶粒大小的较光滑的刻面组成，刻面内裂纹需要跨过若干相互平行的而且位于不同高度的解理面，从而产生了解理台阶和河流花样。这种刻面称为解里刻面。 河流花样 解理断口上的解理刻面内裂纹需要跨过若干相互平行的而且位于不同高度的解理面，从而产生了解理台阶和河流花样。 金属材料常见的塑性变形方式主要为滑移和孪生 弹性模量主要决定于金属原子本性和晶格类型 常用的两个塑性指标为延伸率和断面收缩率 金属的弹性模量主要取决于什么因素,为什么说它是一个对组织不敏感的力学性能指标, 主要决定于原子本性和晶格类型。合金化、热处理、冷塑性变形等能够改变金属材料的组织形态和晶粒大小，但是不改变金属原子的本性和晶格类型。故弹性模量对组织不敏感。 消除包申格效应的方法:预先进行较大的塑性变形，或在第二次反向受力前先使金属材料于回复或再结晶温度下退火，如钢在400-500?，铜合金在250-270?退火。 多晶金属塑性变形的特点:1)各晶粒变形的不同时性和不均匀性2)各晶粒变形的相互协调性 屈服现象有关的三个因素:1)材料变形前可动位错密度小(或虽有大量但被钉扎住，如钢中的位错为杂质原子或第二相质点所钉扎);2)随塑性变形发生，位错能快速增殖;3)位错运动速率与外加应力有强烈依存关系。 影响屈服强度的内在因素:金属本性及晶格类型，晶粒大小和亚结构，溶质元素，第二相 外在因素:温度，应变速率和应力状态 韧性断裂和脆性断裂的区别，为什么断裂最危险, 韧性断裂是金属材料断裂前产生明显的宏观塑性变形的断裂，这种断裂有一个缓慢的撕裂过digging out things, refine, eliminate, and strive to achieve dynamic information highlighting the timeliness, policy focus on targeted, experience information grasp typical problem emphasizes the tendency of information, freedom of information caught ... "Excellence", and accurate, short, does not speak empty words, cliches. "Fast", is the emphasis on timeliness. Who want government leaders to grasp the important information must be collected quickly reported. Especially urgent important information such as events, in strict accordance with the State Council concerning strengthening the emergency notice of significant reporting requirements, not only in the first period of submission to government events, also tracking developments closely, to submit measures, consequences, treatment and rehabilitation, and so on. Establish a strict responsibility system, of late, fail to hide critical situations, to be held accountable. City and County Government offices and Government departments, we should further perfect duty system, raise the level of response and the ability to respond to emergencies and. Third, to open channels of information. Role of key government information network main channel, building extends to all departments and units, vertical extension to the Township and community information networks, information staff, strengthening the work of information. Finished the basic tasks to be criticized. Did not submit information for a long time the County (district) and sectoral, this year we will take effective measuresfacilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and facilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and 程，在裂纹扩展过程中不断地消耗能量;而脆性断裂是突然发生的断裂，断裂前基本上不发生塑性变形，没有明显征兆，因而危害性很大。 剪切断裂与解理断裂都是穿晶断裂，为什么断裂性质完全不同, 剪切断裂是在切应力作用下沿滑移面分离而造成的滑移面分离，一般是韧性断裂，而解理断裂是在正应力作用以极快的速率沿一定晶体学平面产生的穿晶断裂，解理断裂通常是脆性断裂。 何谓拉伸断口三要素,影响宏观拉伸断口性态的因素有哪些, 宏观断口呈杯锥形，由纤维区、放射区和剪切唇三个区域组成，即所谓的断口特征三要素。上述断口三区域的形态、大小和相对位置，因试样形状、尺寸和金属材料的性能以及试验温度、加载速率和受力状态不同而变化。 课后习 题 快递公司问题件快递公司问题件货款处理关于圆的周长面积重点题型关于解方程组的题及答案关于南海问题 16 E,1/2s，代入算得40GPa。 ,(),ma0 课后习题18 ,2EE,1/21/2ss,理论断裂强度为,()，裂纹体断裂强度为，将两式相除可算出脆,(),cm,aa0 性断裂时的断裂应力。 第二章 金属在其他静载荷下的力学性能 应力状态软性系数 材料或工件所承受的最大切应力τmax和最大正应力σmax比值，即: ,,,,max13,,,，，,2,,0.5,，,max123 缺口敏感度 缺口试样的抗拉强度σ的与等截面尺寸光滑试样的抗拉强度σb 的比值，称bn 为缺口敏感度，即: 缺口效应 引起应力集中，并改变了缺口前方的应力状态，由单向应力状态改变呈两向或三向应力状态;使塑性材料强度增高，塑性降低。 布氏硬度 用钢球或硬质合金球作为压头，采用单位面积所承受的试验力计算而得的硬度。 第三章 金属在冲击载荷下的力学性能 A冲击韧度:U形缺口冲击吸收功 除以冲击试样缺口底部截面积所得之商，称为冲击韧KU 度，也是度量材料冲击韧性的一种力学性能指标,。 冲击吸收功: 缺口试样冲击弯曲试验中，摆锤冲断试样失去的位能为mgH1-mgH2。此即为试样变形和断裂所消耗的功，称为冲击吸收功。 digging out things, refine, eliminate, and strive to achieve dynamic information highlighting the timeliness, policy focus on targeted, experience information grasp typical problem emphasizes the tendency of information, freedom of information caught ... "Excellence", and accurate, short, does not speak empty words, cliches. "Fast", is the emphasis on timeliness. Who want government leaders to grasp the important information must be collected quickly reported. Especially urgent important information such as events, in strict accordance with the State Council concerning strengthening the emergency notice of significant reporting requirements, not only in the first period of submission to government events, also tracking developments closely, to submit measures, consequences, treatment and rehabilitation, and so on. Establish a strict responsibility system, of late, fail to hide critical situations, to be held accountable. City and County Government offices and Government departments, we should further perfect duty system, raise the level of response and the ability to respond to emergencies and. Third, to open channels of information. Role of key government information network main channel, building extends to all departments and units, vertical extension to the Township and community information networks, information staff, strengthening the work of information. Finished the basic tasks to be criticized. Did not submit information for a long time the County (district) and sectoral, this year we will take effective measuresunannounced visits to survey and news exposure, more powerful of measures, reflected supervision work of seriousness, and just sex and authenticity. In supervision process in the, both understand the work of progress situation, and note summary units, and the sector in work practice in the created of success experience; both found work in the exists of problem, and find associate produced problem of reasons; both for grass-roots of specific problem, proposed solution of measures and approach, and station in global of height, for Government perfect decision, and guide work proposed macro views, constantly improve supervision work of level. Third, to put the focal point in the system of supervision on the construction. To implement the responsibility system, establish and improve the implementation of the target responsibility system for everyone to task, pressure and power, all your knowledge and wisdom, to find, to form a Government as the main body, inspection Chambers led sector, caught in all aspects of supervision work. To establish supervision authority. Government offices carry out inspection, was authorized by the Government, on behalf of the Government and responsible to the Government, is an important part of government supervision and Extension, has the right to check and coordinate the right, the right to inform the right to criticism, and advice. Departments at all levels should give support to ensure supervision work smoothly. To implementation report system, on main work progress situation to by quarter submitted; on assigned by facilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and 低温脆性: 体心立方晶体金属及合金或某些密排六方晶体金属及其合金，特别是工程上常用的中、低强度结构钢(铁素体-珠光体钢)，在试验温度低于某一温度时，会由韧性状tk态变为脆性状态，冲击吸收功明显下降，断裂机理由微孔聚集型变为穿晶解理型，断口特征由纤维状变为结晶状，这就是低温脆性。 韧脆转变 由于条件的改变，材料的断裂应变突然减小，即断裂性质由延性断裂突然向脆性断裂转变的现象。 试说明低温脆性的物理本质及其影响因素 低温脆性的物理本质:宏观上对于那些有低温脆性现象的材料，它们的屈服强度会随温度的降低急剧增加，而断裂强度随温度的降低而变化不大。当温度降低到某一温度时，屈服强度增大到高于断裂强度时，在这个温度以下材料的屈服强度比断裂强度大，因此材料在受力时还未发生屈服便断裂了，材料显示脆性。 从微观机制来看低温脆性与位错在晶体点阵中运动的阻力有关，当温度降低时，位错运动阻力增大，原子热激活能力下降，因此材料屈服强度增加。 影响材料低温脆性的因素有 1(晶体结构:对称性低的体心立方以及密排六方金属、合金转变温度高，材料脆性断裂趋势明显，塑性差。 2(化学成分:能够使材料硬度，强度提高的杂质或者合金元素都会引起材料塑性和韧性变差，材料脆性提高。 3(显微组织:?晶粒大小，细化晶粒可以同时提高材料的强度和塑韧性。因为 晶界是裂纹扩展的阻力，晶粒细小，晶界总面积增加，晶界处塞积的位错数减 少，有利于降低应力集中;同时晶界上杂质浓度减少，避免产生沿晶脆性断裂。 ?金相组织:较低强度水平时强度相等而组织不同的钢，冲击吸收功和韧脆转变温度以马氏体高温回火最佳，贝氏体回火组织次之，片状珠光体组织最差。钢中夹杂物、碳化物等第二相质点对钢的脆性有重要影响，当其尺寸增大时均使材料韧性下降，韧脆转变温度升高。 第四章 金属的断裂韧度 低应力脆断 材料在屈服强度以下的载荷下工作，发生突然脆性断裂的现象。 应力场强度因子 综合了名义应力和裂纹尺寸，能反映裂纹尖端应力场强度的复合力学参量。 裂纹扩展K判据 根据应力场强度因子(K)与断裂韧度(K)的相对大小，判断裂纹是否1C 扩展，若KK则裂纹失稳扩展。 1C1C 小范围屈服: 塑性区的尺寸较裂纹尺寸及净截面尺寸为小时(小一个数量级以上)，这就称为小范围屈服。 有效屈服应力:裂纹在发生屈服时的应力。 有效裂纹长度:因裂纹尖端应力的分布特性，裂尖前沿产生有塑性屈服区，屈服区内松弛的应力将叠加至屈服区之外，从而使屈服区之外的应力增加，其效果相当于因裂纹长度增加ry后对裂纹尖端应力场的影响，经修正后的裂纹长度即为有效裂纹长度: a+ry。 裂纹扩展能量释放率GI:I型裂纹扩展单位面积时系统释放势能的数值。 KCK,C说明和指标的意义及其相互关系 KCK,CK,CK,答: 临界或失稳状态的记作或，为平面应变下的断裂韧度，表示在平面应 KC变条件下材料抵抗裂纹失稳扩展的能力。为平面应力断裂韧度，表示在平面应力条件下digging out things, refine, eliminate, and strive to achieve dynamic information highlighting the timeliness, policy focus on targeted, experience information grasp typical problem emphasizes the tendency of information, freedom of information caught ... "Excellence", and accurate, short, does not speak empty words, cliches. "Fast", is the emphasis on timeliness. Who want government leaders to grasp the important information must be collected quickly reported. Especially urgent important information such as events, in strict accordance with the State Council concerning strengthening the emergency notice of significant reporting requirements, not only in the first period of submission to government events, also tracking developments closely, to submit measures, consequences, treatment and rehabilitation, and so on. Establish a strict responsibility system, of late, fail to hide critical situations, to be held accountable. City and County Government offices and Government departments, we should further perfect duty system, raise the level of response and the ability to respond to emergencies and. Third, to open channels of information. Role of key government information network main channel, building extends to all departments and units, vertical extension to the Township and community information networks, information staff, strengthening the work of information. Finished the basic tasks to be criticized. Did not submit information for a long time the County (district) and sectoral, this year we will take effective measuresfacilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and facilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and KC,材料抵抗裂纹失稳扩展的能力。 它们都是型裂纹的材料裂纹韧性指标，但值与试样厚度有关。当试样厚度增加，使裂纹尖端达到平面应变状态时，断裂韧度趋于一稳定的最低 K,C值，即为，它与试样厚度无关，而是真正的材料常数。 试述低应力脆断的原因及防止方法。 答: 低应力脆断的原因:在材料的生产、机件的加工和使用过程中产生不可避免的宏观裂纹，从而使机件在低于屈服应力的情况发生断裂。 预防措施:将断裂判据用于机件的设计上，在给定裂纹尺寸的情况下，确定机件允许的最大工作应力，或者当机件的工作应力确定后，根据断裂判据确定机件不发生脆性断裂时所允许的最大裂纹尺寸。 试述K判据的意义及用途。 答: K判据解决了经典的强度理论不能解决存在宏观裂纹为什么会产生低应力脆断的原因。K判据将材料断裂韧度同机件的工作应力及裂纹尺寸的关系定量地联系起来，可直接用于设计计算，估算裂纹体的最大承受能力、允许的裂纹最大尺寸，以及用于正确选择机件材料、优化工艺等。 影响,的因素:内因:,、化学成分的影响;,、基体相结构和晶粒大小的影响; ，, 杂质及第二相的影响;,、显微组织的影响。外因:,、温度;,、应变速率。 第五章 金属的疲劳 疲劳源:是疲劳裂纹萌生的策源地，一般在机件表面常和缺口，裂纹，刀痕，蚀坑相连。P96 疲劳贝纹线 由于载荷突然变动引起偶然过载使疲劳裂纹向前扩展，并在留下弧状台阶痕迹，这些一系列的弧状痕迹在宏观疲劳断口上呈现出贝纹状形貌特征，即疲劳贝纹线。 疲劳条带 疲劳裂纹扩展的第二阶段，在断口上呈现出的具有略弯曲并相互平行沟槽花样的微观形貌特征，称为疲劳条带 驻留滑移带 材料在低于屈服应力的循环载荷下局部地区出现不均匀的循环滑移带，这种循环滑移带具有永留的特性，因此称为驻留滑移带。 ΔK:材料的疲劳裂纹扩展速率不仅与应力水平有关，而且与当时的裂纹尺寸有关。ΔK是由应力范围Δσ和a复合为应力强度因子范围，ΔK=Kmax-Kmin=Yσmax?a-Yσmin?a=YΔσ?a. da/dN:疲劳裂纹扩展速率，即每循环一次裂纹扩展的距离。 疲劳寿命:试样在交变循环应力或应变作用下直至发生破坏前所经受应力或应变的循环次数 疲劳门槛值ΔKth 在疲劳裂纹扩展速率曲线的?区，当ΔK?ΔKth时，da/aN=0,表示裂纹不扩展;只有当ΔK>ΔKth时，da/dN>0,疲劳裂纹才开始扩展。因此，ΔKth是疲劳裂纹不扩展的ΔK临界值，称为疲劳裂纹扩展门槛值。 试述金属疲劳断裂的特点 (1)疲劳是低应力循环延时断裂，即具有寿命的断裂 (2)疲劳是脆性断裂 (3)疲劳对缺陷(缺口，裂纹及组织缺陷)十分敏感 试述疲劳宏观断口的特征及其形成过程 答:典型疲劳断口具有三个形貌不同的区域—疲劳源、疲劳区及瞬断区。 (1) 疲劳源是疲劳裂纹萌生的策源地，疲劳源区的光亮度最大，因为这里在整个裂纹亚 稳扩展过程中断面不断摩擦挤压，故显示光亮平滑，另疲劳源的贝纹线细小。 (2) 疲劳区的疲劳裂纹亚稳扩展所形成的断口区域，是判断疲劳断裂的重要特征证据。digging out things, refine, eliminate, and strive to achieve dynamic information highlighting the timeliness, policy focus on targeted, experience information grasp typical problem emphasizes the tendency of information, freedom of information caught ... "Excellence", and accurate, short, does not speak empty words, cliches. "Fast", is the emphasis on timeliness. Who want government leaders to grasp the important information must be collected quickly reported. Especially urgent important information such as events, in strict accordance with the State Council concerning strengthening the emergency notice of significant reporting requirements, not only in the first period of submission to government events, also tracking developments closely, to submit measures, consequences, treatment and rehabilitation, and so on. Establish a strict responsibility system, of late, fail to hide critical situations, to be held accountable. City and County Government offices and Government departments, we should further perfect duty system, raise the level of response and the ability to respond to emergencies and. Third, to open channels of information. Role of key government information network main channel, building extends to all departments and units, vertical extension to the Township and community information networks, information staff, strengthening the work of information. Finished the basic tasks to be criticized. Did not submit information for a long time the County (district) and sectoral, this year we will take effective measuresunannounced visits to survey and news exposure, more powerful of measures, reflected supervision work of seriousness, and just sex and authenticity. In supervision process in the, both understand the work of progress situation, and note summary units, and the sector in work practice in the created of success experience; both found work in the exists of problem, and find associate produced problem of reasons; both for grass-roots of specific problem, proposed solution of measures and approach, and station in global of height, for Government perfect decision, and guide work proposed macro views, constantly improve supervision work of level. Third, to put the focal point in the system of supervision on the construction. To implement the responsibility system, establish and improve the implementation of the target responsibility system for everyone to task, pressure and power, all your knowledge and wisdom, to find, to form a Government as the main body, inspection Chambers led sector, caught in all aspects of supervision work. To establish supervision authority. Government offices carry out inspection, was authorized by the Government, on behalf of the Government and responsible to the Government, is an important part of government supervision and Extension, has the right to check and coordinate the right, the right to inform the right to criticism, and advice. Departments at all levels should give support to ensure supervision work smoothly. To implementation report system, on main work progress situation to by quarter submitted; on assigned by facilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and 特征是:断口比较光滑并分布有贝纹线。断口光滑是疲劳源区域的延续，但其程度 随裂纹向前扩展逐渐减弱。贝纹线是由载荷变动引起的，如机器运转时的开动与停 歇，偶然过载引起的载荷变动，使裂纹前沿线留下了弧状台阶痕迹。 (3) 瞬断区是裂纹最后失稳快速扩展所形成的断口区域。其断口比疲劳区粗糙，脆性材 料为结晶状断口，韧性材料为纤维状断口。 试述疲劳微观断口的主要特征 断口特征是具有略呈弯曲并相互平行的沟槽花样，称疲劳条带(疲劳条纹、疲劳辉纹)。疲劳条带是疲劳断口最典型的微观特征。 试述金属表面强化对疲劳强度的影响。 表面强化处理可在机件表面产生有利的残余压应力，同时还能提高机件表面的强度和硬度。这两方面的作用都能提高疲劳强度。 表面强化方法，通常有表面喷丸、滚压、表面淬火及表面化学热处理等。 (1) 表面喷丸及滚压 喷丸是用压缩空气将坚硬的小弹丸高速喷打向机件表面，使机件表面产生局部形变硬化;同时因塑变层周围的弹性约束，又在塑变层内产生残余压应力。 表面滚压和喷丸的作用相似，只是其压应力层深度较大，很适于大工件;而且表面粗糙度低，强化效果更好。 (2) 表面热处理及化学热处理 他们除能使机件获得表硬心韧的综合力学性能外，还可以利用表面组织相变及组织应力、热应力变化，使机件表面层获得高强度和残余压应力，更有效地提高机件疲劳强度和疲劳寿命。 digging out things, refine, eliminate, and strive to achieve dynamic information highlighting the timeliness, policy focus on targeted, experience information grasp typical problem emphasizes the tendency of information, freedom of information caught ... "Excellence", and accurate, short, does not speak empty words, cliches. "Fast", is the emphasis on timeliness. Who want government leaders to grasp the important information must be collected quickly reported. Especially urgent important information such as events, in strict accordance with the State Council concerning strengthening the emergency notice of significant reporting requirements, not only in the first period of submission to government events, also tracking developments closely, to submit measures, consequences, treatment and rehabilitation, and so on. Establish a strict responsibility system, of late, fail to hide critical situations, to be held accountable. City and County Government offices and Government departments, we should further perfect duty system, raise the level of response and the ability to respond to emergencies and. Third, to open channels of information. Role of key government information network main channel, building extends to all departments and units, vertical extension to the Township and community information networks, information staff, strengthening the work of information. Finished the basic tasks to be criticized. Did not submit information for a long time the County (district) and sectoral, this year we will take effective measuresfacilitate decision implementation process step by step. Government offices at all levels in accordance with the notice on further strengthening the supervision work of the municipal government requires, and actively carry out supervision from the following aspects. One is to focus supervision on the implementation of the major decisions and arrangements of the municipal government, in leadership on the major issues of concern to implement, on the people reflect strongly on the hot and difficult problems to solve. Current, to tightly around implement implementation municipal, and Municipal Government proposed of "three a insisted two promote, five big storming six breakthrough" of guideline and General requirements, focus in foster four industry, and construction four base, and created four brand and farmers increase, and project construction, and enterprise reform, and city construction, and private economic, and building harmony social, aspects grasp supervision, makes we of supervision work and city of General thought tune, and and reform development of pulse synchronization. Second, supervision of the breakthrough in innovation, improved methods. Supervision of method, to by passive type to active type change, by everything to focus breakthrough change, by assault supervising to track supervising change, in full using sent letter supervision, and phone urged reported, and heard reported, basic method of while, more to used field check, and random checks, and