{"created":"2023-06-19T10:29:45.016863+00:00","id":9750,"links":{},"metadata":{"_buckets":{"deposit":"ffa5219e-5134-4598-a4ff-52eb45d8e128"},"_deposit":{"created_by":18,"id":"9750","owners":[18],"pid":{"revision_id":0,"type":"depid","value":"9750"},"status":"published"},"_oai":{"id":"oai:muroran-it.repo.nii.ac.jp:00009750","sets":["41:227"]},"author_link":["55385"],"item_81_date_granted_17":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2018-09-26"}]},"item_81_degree_grantor_10":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_language":"ja","subitem_degreegrantor_name":"室蘭工業大学"},{"subitem_degreegrantor_language":"en","subitem_degreegrantor_name":"Muroran Institute of Technology"}],"subitem_degreegrantor_identifier":[{"subitem_degreegrantor_identifier_name":"10103","subitem_degreegrantor_identifier_scheme":"kakenhi"}]}]},"item_81_degree_name_11":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（工学）","subitem_degreename_language":"ja"}]},"item_81_description_25":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_81_description_7":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"本研究では肉厚が薄い球状黒鉛鋳鉄を製作するための最適な溶湯組成と鋳造処理について調査した．厚さ2mm の極薄球状黒鉛鋳鉄を鋳造した時に，黒鉛化を促進させ，脆性的な炭化物組織（チル組織）を晶出しない鋳造プロセスを明らかにした．また，熱分析法を用いた薄肉球状黒鉛鋳鉄の溶湯評価方法を検討した．本論文は全6 章で構成されている．第1 章では鋳造材料における薄肉球状黒鉛鋳鉄の位置づけと，製造プロセスにおける課題について解説した．第2章では鋳鉄の基本組成である炭素とけい素に着目し，板厚2mmの薄肉鋳鉄の組織と溶湯組成の関係を明らかにした．薄肉化による冷却速度の増大はセメンタイト共晶反応（チル化）起こしやすい．しかし，共晶組成の合金では，急冷による過冷およびけい素添加による共晶温度の上昇によって，微細な黒鉛を多数晶出させることが可能であり，これにより基地組織の黒鉛化反応を促進してチル化を抑制し，脆化を抑制することができた．第3章では，薄肉鋳鉄のチル化に及ぼす冷却速度の影響を検討した．冷却速度の上昇によるチル化の抑制は，けい素を増加させて炭素当量を増大させた溶湯の方が良好である．これは，添加したけい素による共晶温度の上昇，1450℃以上の溶湯での脱酸効果，および黒鉛生成の核としてのけい素化合物の形成が影響していると考えられる．また，パーライト組織量の増加には炭素当量を調整することが有効である．第4章では，前章で明らかになった条件が実際の生産に適用可能か検討するために，けい素の添加量を増加させずに接種剤と黒鉛球状化剤を使用して，肉厚3mmの薄肉球状黒鉛鋳鉄を鋳造した．接種剤は黒鉛粒数及びパーライト面積率に対する冷却速度の依存性を低下させる効果があり，その効果は0.08mass%のとき最大になる．また，溶湯の冷却過程の熱分析によりチル化に影響を及ぼす溶湯性状を明らかにして，溶湯の評価方法を検討した．熱分析データと黒鉛組織および組成の重回帰分析から，晶出する黒鉛粒数は，再輝反応から共晶反応最高温度に至る直前までの最大冷却速度および炭素当量（CE値）の間に強い相関性があることを明らかにした．第5章では，薄肉鋳鉄部品では衝撃による折れや割れの破損が懸念されるため，チル化を抑制する化学組成と機械的性質の関係を評価した．黒鉛粒数の増大に伴い衝撃値は低下した．また，けい素の含有量は3.66mass%を超えるとけい素の固溶に伴う硬さ上昇によって脆化した．第6は総括であり，溶湯組成，冷却速度，溶湯処理，熱分析の実験で得られた結果から，最適な薄肉球状黒鉛鋳鉄の鋳造条件を提案した．","subitem_description_language":"ja","subitem_description_type":"Abstract"},{"subitem_description":"An optimum molten metal chemical composition and cast treatment was investigated for producing thin wall ductile cast iron in this study. The optimum casting process without brittle cementite structure (chill structure) separating out during casting extremely thin wall ductile cast iron with 2mm thickness was proposed. In addition, the melt evaluation method for thin wall ductile cast iron by using thermal analysis was investigated. The problems in the manufacturing process and the position of thin wall ductile cast iron in casting material were explicated. The carbon and silicon which are in the basic composition of cast iron were focused on and the relationship between the molten melt composition and microstructure of 2mm wall thickness of ductile cast iron was clarified. The cementite eutectic reaction (chilling) was caused easily as the increasing of cooling rate due to reducing the wall thickness. However, the embrittlement could be restrained and the graphitization reaction of the matrix structure was accelerated due to separation by crystallization of a large amount of fine graphite, which is due to the undercooling by quenching and increasing the temperature range of eutectic reaction by the chemical composition constituted by eutectic composition. The influence of cooling speed on the chilling was discussed as the composition was for the thin wall ductile cast iron in chapter 3. The specimen with gradient in plate thickness was casted in order to continuously change the cooling rate. The cooling curve of the molten cast iron in the cup type shell mold (φ30×50mm) used in the carbon equivalent (CE) meter were recorded and analyzed. The first derivative of the cooling curve was used to calculate the characteristic temperature, cooling speed and time of transformation point in eutectic reaction during solidification. Next, the correlation between these melt characteristics and graphite nodule count of thin wall ductile cast iron was analyzed. It was found that the maximum cooling speed (VR-max) of recalescence reaction and carbon equivalent value has a higher correlation with the graphite nodule count of thin wall ductile cast iron. And the formula between the nodule count and CE value, VR-max was established by using regression analysis. The availability of the regression formula was also confirmed. The graphite nodule count could be predicted by this formula. The carbide precipitation could be restrained if the graphite nodule count is over than the critical value. Therefore, it was could be used to evaluate the melt by comparing the critical nodule count and the predicated nodule count.","subitem_description_language":"en","subitem_description_type":"Abstract"}]},"item_81_dissertation_number_13":{"attribute_name":"学位授与番号","attribute_value_mlt":[{"subitem_dissertationnumber":"甲第425号"}]},"item_81_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15118/00009700","subitem_identifier_reg_type":"JaLC"}]},"item_81_subject_9":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"566","subitem_subject_scheme":"NDC"}]},"item_81_text_12":{"attribute_name":"学位の種別","attribute_value_mlt":[{"subitem_text_language":"ja","subitem_text_value":"課程博士"}]},"item_81_text_14":{"attribute_name":"報告番号","attribute_value_mlt":[{"subitem_text_language":"ja","subitem_text_value":"甲第425号"}]},"item_81_text_15":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_text_language":"ja","subitem_text_value":"博甲第425号"}]},"item_81_text_16":{"attribute_name":"研究科・専攻","attribute_value_mlt":[{"subitem_text_language":"ja","subitem_text_value":"工学専攻"}]},"item_81_version_type_24":{"attribute_name":"著者版フラグ","attribute_value_mlt":[{"subitem_version_resource":"http://purl.org/coar/version/c_970fb48d4fbd8a85","subitem_version_type":"VoR"}]},"item_access_right":{"attribute_name":"アクセス権","attribute_value_mlt":[{"subitem_access_right":"open access","subitem_access_right_uri":"http://purl.org/coar/access_right/c_abf2"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorAffiliations":[{"affiliationNameIdentifiers":[],"affiliationNames":[{"affiliationName":""}]}],"creatorNames":[{"creatorName":"王, 強","creatorNameLang":"ja"},{"creatorName":"WANG, Qiang","creatorNameLang":"en"}],"familyNames":[{},{}],"givenNames":[{},{}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2018-11-21"}],"displaytype":"detail","filename":"A425.pdf","filesize":[{"value":"8.7 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"A425","objectType":"fulltext","url":"https://muroran-it.repo.nii.ac.jp/record/9750/files/A425.pdf"},"version_id":"7e34fb7c-2516-45b3-a89f-faf181bd5e9f"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2018-11-21"}],"displaytype":"detail","filename":"A425_summary.pdf","filesize":[{"value":"169.6 kB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"A425_summary","objectType":"abstract","url":"https://muroran-it.repo.nii.ac.jp/record/9750/files/A425_summary.pdf"},"version_id":"b801662f-480f-419b-a12e-ec625e2e76ab"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"jpn"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"doctoral thesis","resourceuri":"http://purl.org/coar/resource_type/c_db06"}]},"item_title":"薄肉球状黒鉛鋳鉄の鋳造における溶湯組成調整と処理に関する研究","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"薄肉球状黒鉛鋳鉄の鋳造における溶湯組成調整と処理に関する研究","subitem_title_language":"ja"},{"subitem_title":"Study on Chemical Composition Adjustment and Treatment of Molten Metal during Casting Thin Wall Ductile Cast Iron","subitem_title_language":"en"}]},"item_type_id":"81","owner":"18","path":["227"],"pubdate":{"attribute_name":"PubDate","attribute_value":"2018-11-21"},"publish_date":"2018-11-21","publish_status":"0","recid":"9750","relation_version_is_last":true,"title":["薄肉球状黒鉛鋳鉄の鋳造における溶湯組成調整と処理に関する研究"],"weko_creator_id":"18","weko_shared_id":-1},"updated":"2024-01-22T02:40:35.773986+00:00"}