BNITROGENFISSUREDC

1、Training Module11CASTING DEFECTS NITROGEN FISSURE DEFECTS 141 B5铸件缺陷铸件缺陷氮气缩松氮气缩松141 B5141 B5Training Module12Defect Identification some basic principles缺陷的识别缺陷的识别一些基本原则一些基本原则Process of identificationTake a Photo 排照Examine using a magnifying lens 放大镜观察Examine with a micro scope 显微镜观察SEM if required如必

2、要采用电镜扫描Record and Graph results 记录并制成图表Map Process 流程图141 B5Training Module1Typical Characteristics 典型特征典型特征Typically surface or sub-surface irregular formed cavities.典型形状是产生在铸件表面或者皮下的不规则气腔The cavity face is smooth气腔表面光滑Normally perpendicular to the surface, and may penetrate several mm into the cas

3、ting, and be several mm wide通常与表面垂直，可能向铸件内部深入几毫米，宽也可能达几毫米The cavity is normally black and shiny, with dendrites present in the cavity.气腔内部呈现黑色有光泽且伴有枝晶The graphite flakes in the surrounding area is normally depleted.缺陷周围的石墨通常被消耗掉了Mainly occur in grey iron (FC) but can occur in ductile iron (FCD) at h

4、igher Nitrogen levels主要产生在灰铁铸件上，但是如果球铁件的氮含量高也可能产生No inclusions of other types are normally found associated with fissures通常情况下，没有其他孔洞缺陷伴生3NITROGEN FISSURE DEFECTS氮气孔（裂隙）缺陷氮气孔（裂隙）缺陷Nitrogen Fissure Defect- Characteristics141 B5Training Module1Schematic 图示图示Typically surface or sub-surface irregular f

5、ormed cavities.典型形状是在铸件表面或者皮下产生的气腔Often found adjacent to Core surfaces通常在芯子表面附近可见4Nitrogen Fissure Defects Schematic ViewNitrogen Fissure Defects氮气缩松缺陷氮气缩松缺陷Fissure DefectsTyp 2 to 20mmCore or mould141 B5Training Module1Microstructure 微观结构微观结构Typically surface or sub-surface irregular formed caviti

6、es.主要是表面或者皮下形成的不规则气腔The cavity face is smooth气腔表面光滑Normally perpendicular to the surface, and may penetrate several mm into the casting, and be several mm wide通常与表面垂直，可能向铸件内部渗透几毫米深几毫米宽The cavity is normally black and shiny, with dendrites present in the cavity.气腔内部呈现黑色有光泽且伴有枝晶The graphite flakes in

7、the surrounding area is normally depleted.缺陷周围的石墨通常被消耗掉了Mainly occur in grey iron (FC) but can occur in ductile iron (FCD) at higher Nitrogen levels主要产生在灰铁铸件上，但是如果球铁件的氮含量高也可能产生No inclusions of other types are normally found associated with fissures产生缩松时，包括砂眼类任何缺陷都不同时产生Nitrogen Pinholes are normally

8、rounded in shape氮气针孔通常是圆形的5Nitrogen Fissure Defects MicrostructureNitrogen Fissure Defects氮气缩松缺陷氮气缩松缺陷141 B5Training Module1Typical Occurrence of the Nitrogen Fissures 氮氮气缩松的典型形成情况气缩松的典型形成情况Nitrogen defects are more likely to occur in areas of thick walls in Grey iron (FC)氮气缺陷易于产生在灰铁厚壁上They can occu

9、r in Ductile iron (FCD).主要产生在灰铁铸件上They normally occur adjacent to core or mould areas.通常产生在芯子或者砂模附近的位置The surface is normally black, and the area surrounding the defect has depleted graphite formation. 表面通常呈现黑色，缺陷周围有石墨消耗的痕迹The defect can be both surface and sub surface.这种缺陷即在铸件表面又在皮下产生The defect has

10、 increased with the increase in melting steel scrap这种缺陷会随着废钢熔炼量的增加而增加6Nitrogen Fissures Typical OccurrenceNITROGEN FISSURE DEFECTS氮气缩松缺陷氮气缩松缺陷141 B5Training Module1Physics of Defect Forming 缺陷形成的物理原因缺陷形成的物理原因The fissures are formed due to precipitation of Nitrogen during solidification.缩松是在硬化过程中由于氮元

11、素的突然析出形成。They appear as crack like cavities, with a dendritic structure缩松看起来像是有枝茎结构的空腔。The defect is further intensified due to the simultaneous precipitation of Hydrogen.这种缺陷在氢元素析出的同时进一步强化。They are more likely to occur in the heavier sections, and can appear over larger areas than other blow holes这

12、种缺陷在厚壁铸件上更易于产生，比其他气孔类缺陷产生的范围更大7Nitrogen Fissures Physics of Defect FormationNITROGEN FISSURES氮气缩松氮气缩松141 B5Training Module1METALLURGICAL 熔炼熔炼N Content in melt too high. Greater than 100ppm铁水中氮含量过高。高于100ppm。Ti content low relative to N content. Ti binds the N较氮含量而言，钛含量低。钛能包裹氮元素。CE low.碳当量低。Steel char

13、ge proportion too high废钢炉料比例过高。Use of high N raw materials recarburiser for example.使用的原料氮含量高例如增碳剂8Nitrogen Fissures Contributing Factors氮气缩松氮气缩松-形成因素形成因素Nitrogen Fissures Metallurgical Contribution Factors141 B5Training Module1SYSTEM SAND 系统砂系统砂High CB - High water content. 紧实率高水分含量高High N content

14、from core sand influx, or LC producer进入系统的芯砂氮含量高，或者产生光亮碳的物质氮含量高9Nitrogen Fissures Contributing Factors氮气缩松氮气缩松-形成因素形成因素Nitrogen Fissures System Sand Contribution Factors141 B5Training Module1RESIN BONDED SAND Cores 树脂砂芯树脂砂芯Cold Setting and Hot Setting resin binders often contain proportions of Urea

15、resin with high Nitrogen content冷芯树脂和热芯树脂粘结剂通常含有一定量的含氮量高的尿素树脂Too high N in core binder芯子粘结剂的氮含量太高Too much core binder %使用芯子粘结剂太多Insufficient venting of core gases芯子排气不充分10Nitrogen Fissures Contributing Factors氮气缩松氮气缩松-形成因素形成因素Nitrogen Fissures Resin Sand Contribution Factors141 B5Training Module1Gat

16、ing & Pouring浇注系统浇注系统&浇注浇注Too low pouring Temperature浇注温度太低Too slow pouring rate浇注速度太慢11Nitrogen Fissures Contributing Factors氮气缩松氮气缩松-形成因素形成因素Nitrogen Fissures Gating & Pouring Contributing Factors141 B5Training Module1Pattern & Layout 型板型板&布局布局Ensure core gas is well vented pre

17、vent metal blocking core venting确保芯子充分排气避免铁水阻碍芯子排气孔排气12Nitrogen Fissures Contributing Factors氮气缩松氮气缩松-形成因素形成因素Nitrogen Fissures Pattern & Layout Contributing Factors141 B5Training Module1METALLURGICAL 熔炼熔炼Reduce % of steel used in charge.减少炉料中的废钢用量 Reduce N to 100ppm. (85ppm for heavy sections,

18、120ppm for thinner sections)将氮含量降至100ppm。（壁厚的铸件85ppm，壁薄的铸件120ppm。）Add Ti or Zr to melt to bind N. 添加钛或者锆来熔解和包裹氮元素Increase Carbon Equivalent. C & Si reduce N solubility提高碳当量。碳和硅能够减少氮的溶解性。Avoid high N containing recarburiser避免使用含氮量高的增碳剂13Nitrogen Fissures Possible Corrective Actions氮气缩松氮气缩松-可行的改善措

19、施可行的改善措施Nitrogen Fissures Metallurgical Corrective Actions141 B5Training Module1SYSTEM SAND 系统砂系统砂Reduce moisture content. Lower CB降低水分含量。降低紧实率。Better Bentonite development or reduce Bentonite %.提高膨润土性能的发挥或者减少膨润土加入量。Reduce N in sand, use low N LC producer.降低型砂氮气含量，使用低氮的光亮碳产生物。Reduce N content of core sand influx.降低芯砂中氮含量。14Nitrogen Fissures Possible Corrective Actions氮气缩松氮气缩松可行的改善措施可行的改善措施Nitrogen Fissures System Sand Corrective Actions141 B5Training Module1CORE SAND 芯砂芯砂Use low N binder使用低氮含量的粘结剂Use binder with less gas.使用产生气体少的粘结剂Add iro