The Effect of Alloying Addition and Heat Treatment on High Temperature Strength and Structure of 18Cr-12Ni-3Mo Austenitic Heat Resisting Steel Containing Boron

KAWABE Yoshikuni, NAKAGAWA Ryuichi, MUKOYAMA Tamotsu

doi:10.2355/tetsutohagane1955.54.1_48

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Other Title

ボロンを含む18Cr-12Ni-3Mo系オーステナイト耐熱鋼の高温強度と組織におよぼす添加元素と熱処理の影響
ボロンオフクム 18Cr-12Ni-3Moケイオーステナイトタイネツコウノコウオンキョウドトソシキニオヨボステンカゲンソトネツショリノエイキョウ

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The effect of alloying element such as C, B, Ti and Nb, and heat treatment on the high temperature strength and micro structure of 18Cr-12Ni-3Mo austenitic heat resisting steels containing boron were investigated.<BR>In B addition, creep rupture strength increased with increasing B content, whereas in C addition, tit reached maximum at 0.2%C. These effects were ascribed mainly to a precipitation hardening duevto M₂₃C₆ occurring during creep. The effects of Ti and Nb additions on creep rupture strength were given as a function of (Ti+Nb)/C (atomic percent ratis) irrespective of C contents, and gave a maximum effect at (Ti+Nb)/C=0.4-0.8. Therefore, these effects of Ti and Nb additions were ascribed partly to a change in morphology and growth rate of M₂₃C₆, into which Ti and Nb were dissolved.<BR>Moreover, creep rupture strength increased with increasing solution temperature, up to 1250°C. Surprisingly, the eutectic structures had no negative effect upon creep rupture strength of the steels.<BR>Also, the complex borides in these alloys were identified by X ray and chemical analyses. The relation between the sort of borides and eutectic temperature was also discussed.

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Tetsu-to-Hagane

Tetsu-to-Hagane 54 (1), 48-68, 1968

The Iron and Steel Institute of Japan

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