# 硬質材料のσ_m=ψK_<IC>S_<mf>^<1/2>式によるK_<IC>評価値における停止亀裂起因誤差Error Due to Stopped Cracks in K_<IC> Value Estimated by Equation of σ_m=ψK_<IC>S_<mf>^<1/2> for Hard Materials

## 抄録

In our previous study, we have theoretically derived an equation of σ<SUB>m</SUB>=ψK<SUB>IC</SUB>S<SUB>mf</SUB><SUP>1/2</SUP> based on the fracture theory for general hard materials, where σ<SUB>m</SUB> is the flexural strength of test piece, ψ is a factor, K<SUB>IC</SUB> is the fracture toughness and S<SUB>mf</SUB> is the total macroscopic area of fracture surfaces of all fragments of one test piece, and also experimentally confirmed it's validity on two kinds of hard materials, i.e., WC-Co cemented carbides and Si<SUB>3</SUB>N<SUB>4</SUB> base ceramics. In this study, the error due to stopped cracks (cracks which do not cause the formation of fragments, but generate internal fracture surfaces) in the relative value of K<SUB>IC</SUB> estimated by using the above equation was investigated on WC-10mass%Co cemented carbide (the size of test piece is 4×3×36mm<SUP>3</SUP> and the span of ii e is 30mm).<BR>The results obtained were as follows; (1)The total macroscopic area of internal fracture surfaces formed by stopped cracks (S<SUB>c</SUB>) increased from 4.7 to 9.3mm<SUP>2</SUP> with increasing σ<SUB>m</SUB>. However, the ratio of S<SUB>c</SUB>/S<SUB>mf</SUB> was almost constant; 0.05-0.06. (2)A linear correlation was found between σ<SUB>m</SUB> and (S<SUB>m ?? </SUB>+S<SUB>c</SUB>)<SUP>1/2</SUP> in similar manner to σ<SUB>m</SUB>-S<SUB>mf</SUB><SUP>1/2</SUP> relation. The slope of the correlation line (ψK<SUP>c</SUP><SUB>IC</SUB>; K<SUP>c</SUP><SUB>IC</SUB> is the fracture toughness estimated by taking into consideration S<SUB>c</SUB>) was nearly the same as that of σm-Smf1/2 correlation line (ψK<SUB>IC</SUB>) in accordance with the results that K<SUP>c</SUP><SUB>IC</SUB>/K<SUB>IC</SUB> expressed as {S<SUB>mf</SUB>/(S<SUB>mf</SUB>+S<SUB>c</SUB>)}<SUP>1/2</SUP> was 0.97-0.98 and the error estimated by equation (K<SUB>IC</SUB>-K<SUP>c</SUP><SUB>IC</SUB>)/K<SUP>c</SUP><SUB>IC</SUB> is about 2.5%. Therefore, it was concluded that the error due to stopped cracks or S<SUB>c</SUB> is negligible.

## 収録刊行物

• 粉体および粉末冶金

粉体および粉末冶金 43(4), 526-530, 1996-04-15

Japan Society of Powder and Powder Metallurgy

## 参考文献:  4件中 1-4件 を表示

• <no title>

簗場豊

日本金属学会誌 57, 1352, 1993

被引用文献2件

• <no title>

簗場豊

日本金属学会誌 58, 1327, 1994

被引用文献3件

• <no title>

簗場豊

粉体および粉末冶金 42, 417, 1995

被引用文献2件

• <no title>

簗場豊

日本金属学会講演概要 238, 1995

被引用文献1件

## 各種コード

• NII論文ID(NAID)
10002012014
• NII書誌ID(NCID)
AN00222724
• 本文言語コード
JPN
• 資料種別
ART
• ISSN
05328799
• NDL 記事登録ID
3954820
• NDL 雑誌分類
ZP41(科学技術--金属工学・鉱山工学)
• NDL 請求記号
Z17-274
• データ提供元
CJP書誌  CJP引用  NDL  J-STAGE

ページトップへ