PURPOSE: To improve the hot workability and machinability of the free cutting stainless steel while retaining the characteristics of an austenitic stainless steel by incorporating specified amt. of N as well as B into a stainless steel having specified compsn.
CONSTITUTION: The free cutting stainless steel contains, by weight, ≤0.1% C, ≤2.0% Si, ≤3.0% Mn, 13 to 25% Cr, 6 to 20% Ni, 0.01 to 0.10% B, >0.10 to 0.20% N and the balance Fe. In the steel, BN is formed by the addition of B and N to improve the machinability. Since BN has high oxidation resistance at a high temp., high temp. lubricity is made good. In the above steel, since B forms BN, the addition of ≥0.01% is required, but, even if large amounts are added, the effect of improving machinability is saturated and, on the contrary, the machinability is deteriorated, so that the quantity is regulated to ≤0.10%. Since N stably forms BN and drastically improves the machinability, the quantity of >0.10% is required, but, large amounts of addition deteriorates the hot workability, so that the quantity of ≤0.20% is regulated.
ISHIZAKI TETSUYUKI
SANPEI TETSUYA
| JPS6230859A | 1987-02-09 |
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