Effect Of Inclusions On Impact Properties Of Several Cast Steels

The article traced and summarized the actual production and smelting process of castcarbon steel ZG310-570, ZG275-485, GR70-40. It was found that non-metallic inclusions wasmain source and invetiable in the smelting link. The inclusions increased the generationprobability of inner crack, improved greatly the sensitivity of impact fracture of the cast steels.In order to find out the level, the size, the shape etc of inclusion effect on the impact propertiesof cast steels. Furthermore, improved the quality of the actual castings. Impact test was madefor the carbon steel ZG310-570, selceted the sample, analysed the electronic scanning of theeach selection samples impact fracture. Then selected the cross-section near the fracture, ratethe inclusion under the light microscope by the most bad field. More, for explore the inclusioneffect on the impact properties of the alloy steels, the same test was made for the alloy steel0Cr13Ni5Mo applied on the impellers.The impact curve and its characteristic values of the carbon steel ZG310-570and alloystainless steel0Cr13Ni5Mo were obtained during the test, the scanning electron image of theimpact fractures, the relation graph of the level, size and quantity of non-metallic inclusionand impact energy. The test proved that the main structure of the impact curves were the crackforming and crack propagation, and the greater of the proportion of the crack forming, thelarger impact energy was, the impact properties was better. The SEM image showed that theinclusion was the crack sources and changed the energy of the crack forming and propagationduring cracking. Thus, transformed the proportion of the crack forming and propagation in thecruves, changed the impact propeties of cast steels. It was found from the relation graphbetween inclusions and impact energy, for keep favorable impact properties of ZG310-570and0Cr13Ni5Mo, restricted the worst rate of category D inclusions under3.0and arising ofcategory A&B inclusions.