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) aPM ( σ)aPM)aPM( σ( σε00ε0000εε00000ε0ε 0BWBWHHH )aPM( σ( σ )aPM)aPM(STBW)aPM( σFig. 10に引張強さの比較を示す。Fig. 11に引張強さに及ぼす水素の影響を示す。水素チャージ後のHS1鋼母材試験片の引張強さはTS-H＝725 MPaで，HS1鋼母材試験片のTS＝1469 MPaと比べ半減し，水素チャージ部で脆性破壊した（Table 5，Fig. 4（d））。 (a)200015001000with H 5000.052000(b)150010005000.05Fig. 7. Stress (σ)-strain (ε) curves for TM steel of (a) base metal without and with hydrogen charging, (b) spot-welded test specimen without and with hydrogen charging. 2000(a)15001000500with H0.052000(b)150010005000.05Fig. 8. Stress (σ)-strain (ε) curves for HS1 steel of (a) base metal without and with hydrogen charging, (b) spot-welded test specimen without and with hydrogen charging. without H 0.150.20.1without Hwith H 0.150.20.1without H0.10.150.2withoutHwith H0.150.20.1水素チャージ後のTM鋼母材試験片の引張強さはTS-H＝1126 MPaで，水素チャージ後のHS1鋼母材試験片の引張強さTS-H＝725 MPaと比べ，水素脆化の影響が小さい（Fig. 10，Fig. 11）。水素チャージ後のTM鋼溶接試験片はTS-WH＝929 MPaで，水素チャージ後のHS1鋼溶接試験片のTS-WH＝811 MPaと比べ，水素脆化，スポット溶接の影響が小さい（Fig. 10，Fig. 11）。 2000150010005002000150010000.25500Fig. 9. Stress (σ)-strain (ε) curves for HS7 steel of (a) base metal without and with hydrogen charging, (b) spot-welded test specimen without and with hydrogen charging. 0.25200015000.251000500Fig. 10. Tensile strength and maximum stress of TM steel, HS1 steel, and HS7 steel, in witch “B”, “W”, “H” and “WH” denote “Base sample”, “Spot-welded sample”, “Hydrogen charged sample” and “Spot welded and hydrogen charged sample”, respectively. 0.25- 50 -(a) without Hwith H(b) with H 0.050.10.15WHTMHS1Steel 0.050.10.15without H 0.20.25WHWHHS70.20.25