報告書番号

U86024

タイトル（和文）

電炉鉄筋の品質・性能

タイトル（英文）

QUALITIES AND PERFORMANCES OF ELECTRIC FURNACE STEEL REINFORCING BARS

概要 （図表や脚注は「報告書全文」に掲載しております）

中部北西地域６社の電炉鉄筋の母材及びガス圧接継手について確性試験を行い関東以北地域分の試験結果と比較した。又曲げ戻し試験法の提案を行った。確性試験結果は■母材の常温引張特性はＪＩＳ値にすべて合格している■母材の低温引張特性は鋼材の温度依存性のとおりである。－１６５℃では脆性破断をするものが生じた■ガス圧接継手の低温引張特性は母材と同称であるが－１００℃以下では脆性破断をするものがやや多くみられた■平均応力１６■／平方■における疲労特性はａ＝２１．８９－２．４６ｌｏｇ１０Νであらわされる。関東以北分との比較は－１００℃以下での脆性破断が中部以西分の方がやや多いがＪＩＳの要求性能，繰返し曲げ，衝撃，硬化性，顕微鏡組織，疲労の諸性能は殆ど同等と考えられる。曲げ戻し試験は曲げ半径０．５Ｄでのパイプ曲げで行い時効処理は１００℃で１時間加熱後水冷する。９０°曲げた状態を０とし直棒状態に曲げ戻す過程

概要 （英文）

PROOF TESTS WERE CONDUCTED ON THE ELECTRIC FURNACE REINFORCING BARS PODUCED BY SIX COMPANIES IN THE WEST OF CHUBU DISTRICT CONCERNING THEIR BASE METAL AND GAS WELDED JOINTS. THE RESULTS WERE COMPARED WITH THOSE PRODUCED IN THE DISTRICT NORTH OF KANTO AREA. A BENDING AND STRAIGHTENING TEST METHOD WAS PROPOSED. PROOF TESTS SHOWED :(1)ALL THE TENSILE PROPERITIES AT ROOM TEMPERATURE PASSED THE REQUIREMENT SPECIFIED IN JIS. (2)COLD TENSILE PROPERTIES OF BASE METALS WERE IDENTICAL TO THE TEMPERATURE DEPENDENCE OF STEEL. SOME BARS SHOWED BRITTLE FRACTURE AT -165 GRADIENT (3)COLD TENSILE PROPERTIES OF GAS WELDED JOINTS WERE ALMOST INDENTICAL TO THOSE OF BASE METALS,BUT THE FORMER SHOWED MORE BRITTLE FRACTURES THAN THE LATTER BELOW -100GRADIENT. (4)THE FATIGUE PROPERTY AT THE AVERAGE STRESS OF 16KGF/SQUARE MM COULD BE EXPRESSED AS A=21.89-2.46LOG10 N (KGF/SQUARE MM). COMPARING WITH THE PRODUCTS IN DISTRICTS NORTH OF KANTO WESTERN BARS SHOWED SLIGHTLY MORE BRITTLE FRACTURES BELOW -100GRADIENT. BUT REQUIRES PROPERTIES IN JIS,AND THOSE OF FLEXIBILITY,IMPACT,HARDENABILTY,AND MICROSTRUCTURE WERE CONSIDEREDALMOST THE SAME. IN THE PROPOSED FLEX TEST,BARS ARE BENT TO BEND RADIUS OF 0.5D USING A PIPE. IN AGING TREATMENT,BARS ARE HEATED AT 100GRADIENT FOR AN HOUR,AND THEN WATER COOLED. THE ANGLE IS EXPRESSED AS 0 GRADIENT WHEN A BAR WAS BENT TO 90 GRADIENT,AND THE ANGLE AT WHICH THE TESTED BAR BREAKS OR CRACKS DURING STRAIGHTENING IS TAKEN AS THE MEASURE.

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