steelmakingandkeyqualitypointsofsteelmaterial2014Jan分解.ppt

2.2 Mechanical properties We can assess bending properties of steel plate through hardness test before bending plate. We know how to use properties data of steel to guide production. We will not unilaterally rely on Certificate from steel company. 2.2 mechanical properties Steel factory enforced an inequality item on us: “steel factory ensures mechanical properties, or UT acceptance. Not ensure both for thick plate.” How can we do? 2.2 mechanical properties In fact, I want to ensure both UT and F I will answer the question: Ensure mechanical properties. However, after rolling, steel factory must put thick plate in slow cooling pit and cover them with asbestos. 2.2 mechanical properties A low cost and effective method it is: Improve quality through right production. Slow cooling can avoid crack or hole in core of thick plate. Therefore, it can ensure UT acceptance. Decrease UT test cost and labor. Avert inequality item for us. In fact I require wholly quality of thick plate through ensuring mechanical properties. 2.3 Further requirements to steel Compression rate Grain size Inclusion Hardenability Metallographic phase 2.3 Further requirements to steel Compression rate=4 for forgings Grain size should be better than grand 5. Hardenability test is according to ASTM A255. 2.3 Further requirements to steel Inclusion 2.3 Further requirements to steel In 2006, a steel track shoe burst into layer after quenching and low temperature tempering. It is a serious accident. I was responsible to investigate the reason. My opinion is that the cause is Al2O3 tumors in steel when casting. Then the supplier, Fushun steel factory sent the specimen to Shenyang City and inspected it with SEM machine. Quality accident caused by inclusion 2.3 Further requirements to steel How can we remove Al2O3 tumors? We should suggest Ca treatment and change Al2O3 inclusion to low-melting-point CaO-Al2O3 inclusion pouring with liquid steel. So, tumors will disappear. 2.3 Further r