| Popis: |
1. Additional alloying of a steel containing 0. 15% C, 12% Cr and 0. 5% Mo with up to 0.4% V, up to 0. 8% W and up to 0. 8% Cb together or separately increases the relaxation resistance of the basis steel. The greatest effect is exerted by Table 2. Phase Composition of Steels under Study. Heat No. COMPOSITION OF CARSIDE RESIDUE IN % OF WEIGHT OF DISSOLVED METAL X-RAY ANALYSIS DATA Cr Mo W V Co Fe TOTAL CARBIDE PHASE LATTICECONSTANTk X 2 1,54 0,16 — 0,12 — 0,57 2,39 \(\} Me_{23} C_6 (V_c )\) 10,65 1,6 0,15 — 0,26 — 0,56 2,57 10,65 3 0,78 0,22 0,27 0,01 — 0,76 2,04 10,65 5 0,17 0,11 0,13 0,01 — 0,71 1,13 \(\} Me_{23} C_6 \) NOT DE- 6 1,78 0,1 0,85 TRACE — 0,82 3,55 Termined 7 1,72 0,13 0,46 * — 0,3 2,61 8 1 0,28 1,8 * — 1,5 4,58 Me23C6 10,65 (Fe, Cr, W,Mo, V) n C 11,1 13 0,4 0,02 — — 0,3 0,12 0,84 \(\} _{Me_{23} C_6 }^{Nb C} \) 4,46 15 0,2 0,01 — — 0,8 0,1 1,11 4,46 18 0,9 0,1 — 0,005 0,7 0,19 1,89 4,46 19 1,55 0,33 — 0,006 0,7 0,47 3,06 10,65 20 1,47 0,15 — 0,01 0,5 0,67 2,8 10,65 21 2 0,25 — 0,004 0,8 0,8 3,85 10,65 23 0,56 0,18 0,18 TRACE 0,4 0,4 1,72 \(\mathop \} \nolimits_{Me_{23} C_6 }^{Cb C} \) 4,46 24 0,63 0,22 0,51 * 0,4 0,88 2,64 25 0,9 0,28 1,66 * 0,4 0,7 5,04 10,65 simultaneous action of all three elements. 2. The relaxation resistance of the steels studied is largely determined by the ratio between their constituents (sorbite and ferrite), and the degree of hardening and stability of ferrite. To ensure high relaxation resistance, the alloying of high-chromium steel should harden ferrite sufficiently and increase the stability of the ferrite and carbide phases to the limit. 3. Requirements concerning steel for fastening elements at 565 °C (relaxation resistance) can be satisfied by the following steels: %C %Cr %Mo %V %Cb %W 0.2 12 0.8 0.3 0.8 0.2 12 0.5 0.4 0.5 0.5 |
