无损检测缺陷分析.pptx

《无损检测缺陷分析.pptx》由会员分享，可在线阅读，更多相关《无损检测缺陷分析.pptx（23页珍藏版）》请在得力文库 - 分享文档赚钱的网站上搜索。

1、（2）Dialectical analysis of process defects The absoluteness of defect generationIn actual production,the acquirement of the products without any defects is quite difficult；It is not economical or even impossible to make the products produced in batches without any defects.The relativity of defect ev

2、aluation standardsThe relativity of waste standards.As for the same of various parts,the quality requirements are different due to the different working conditions.Therefore,the waste standards are also different.第1页/共23页 Formulation principle of waste standards：Generally speaking,the higher the pro

3、duct quality level is,the greater the risk after failure will be,and the control of defects should be more strict.Therefore,It is necessary to pay attention to the implementation and reference to the relevant standards,which is also called the principle of fitness for purpose.第2页/共23页 Repair of proc

4、ess defects：Minor defect that do not affect the application can be tolerated.Serious defect that do not meet the requirements must be treated.Some defects can be repaired in time,and some defects may not be repaired which must be sentenced to waste.第3页/共23页Examples比如：Excessive reinforcement，属于焊缝形状不良

5、，严重时可以Grinding；必要时grinded the reinforcement smooth。再如：sand inclusion on the surface of casting，可以通过repair welding来修复。特别指出，考虑到焊接接头组织和性能的恶化，某些产品的welding repair不允许超过2次！所以，应该注意formulate a rigorous repair process，否则就会造成Economic loss！第4页/共23页 2.1.2 Classification of process defects 工艺缺陷种类繁多，产生原因也相当复杂。为了便于

6、分析和处理工艺缺陷、制定检验工艺、方便技术交流，有必要对其进行分类。(1)(1)按technical connotation大体分为：Manufacturing and assembly defects如焊件groove angle、assembling gap不均匀，unfitness过大等；Shape and size defects如deformation、inconformity of the width of bead、Excessive reinforcement、collapse、spill-over、overlap等等；第5页/共23页 Geometric discontinu

7、ous defect 如焊件中的裂纹、孔洞、夹杂、未熔合、未焊透，铸件中的缩孔、疏松、裂纹等等；Microstructure and performance defect如机械性能不良、耐腐蚀性下降、过热组织、脆性组织、偏析等等；Other process defects 如spatter、scratch on surface、arc scratch、gouge、grinding defect 第6页/共23页（2）按process technique分为:Welding defect因实施焊接工艺而引起的缺陷；Casting defect因实施铸造工艺而引起的缺陷；Forging defec

8、t因实施锻造、冲压工艺而引起的缺陷；Heat treatment defect（略）第7页/共23页（3）按Defect property不同分为：Crack如冷裂纹、热裂纹、再热裂纹、层状撕裂、火口裂纹等；Hole如缩孔、气孔等；Solid inclusion如夹渣、夹钨等；Faulty fusion如坡口未熔合、层间未熔合；Incomplete fusion如根部未焊透、中部未焊透；Other defects未包含在以上5种缺陷中的缺陷，如undercut、burnthrough、weld beading、arc scratch.第8页/共23页（4）按buried depth of de

9、fects分为：Surface defect如表面气孔、表面裂纹、砂眼、咬边等；Near surface defect如皮下气孔、夹杂等；Internal defect如内部夹杂、气孔、缩孔、裂纹、未熔合、未焊透等；(5)(5)按缺陷的geometrical characteristic不同分为：volumetric defect 如孔洞、夹杂等；area type defect如裂纹、未熔合、夹层等；第9页/共23页（6）按具体缺陷的position feature又有不同的称谓：例如：裂纹可分为：HAZ crack、weld crack、crater crack、toe crack、roo

10、t crack；未熔合可分为：groove incomplete fusion、incomplete fusion between layers、root department incomplete fusion（7）其它分类：According to different tendencies：transverse crack、longitudinal crack、chevron crack、radiate crack；According to different sizes：macro crack、micro crack第10页/共23页According to the mechanism

11、of defect production,there are different classifications,such as：The cracks in welded joints：hot crack、cold crack、reheat crack、lamellar tearing；The porosity in welded joint：hydrogen porosity、nitrogen porosity、carbon monoxide porosity第11页/共23页Crack defects(必须避免)第12页/共23页Faulty fusion defects熔化焊时，在焊缝金

12、属与母材之间或焊道金属之间未能完全熔化结合而留下的缝隙。有侧壁、层间和根本未熔合等。危害：面状缺陷，易造成应力集中，危害性大，不允许。产生原因：层间和坡口侧壁渣清理不干净；焊接电流偏小；焊条偏离坡口侧壁距离太大；焊条摆动幅度太窄等；第13页/共23页Incomplete fusion危害：削弱截面积引起应力集中，削弱连接强度可达60-80%。产生原因：坡口角度或间隙过小，钝边过大、坡口边缘不齐或装配不良；工艺参数不当、坡口清理不干净等。第14页/共23页Holes危害：影响外观，结合强度等；产生原因：焊接材料，气体介质、焊丝和母材表面上的油锈等，金属蒸发等第15页/共23页Undercut-咬边危害：造成局部应力集中。产生原因：焊接工艺参数选择不当第16页/共23页焊缝超高第17页/共23页第18页/共23页第19页/共23页电弧擦伤-不允许第20页/共23页第21页/共23页第22页/共23页感谢您的观看！第23页/共23页