Claims
- 1. An as-deformed billet of free machining steel, said billet comprising:
- a composition consisting essentially of, in wt.%:
- ______________________________________carbon 0.06-1.0manganese 0.30-1.6sulfur up to 0.35bismuth 0.10-0.40tellurium machinability increasing amounts up to 0.06lead up to 0.15silicon up to 0.30phosphorus up to 0.12iron essentially the balance;______________________________________
- the combined lead plus bismuth content being at least 0.25 wt.%;
- all of said tellurium being combined substantially with said bismuth and/or said manganese as microinclusions of Bi.sub.2 Te.sub.3 and/or MnTe;
- there being substantially no FeTe;
- microinclusions of elemental bismuth;
- a billet surface substantially free of surface cracking and burning in the as-deformed condition;
- and iron oxide on the surface of said billet in said as-deformed condition;
- said billet having microinclusions of PbTe in amounts insufficient to produce substantial surface cracking during hot deforming of said billet at a temperature below 1150.degree. C. (2100.degree. F.).
- 2. A billet as recited in claim 1 wherein:
- said tellurium content is 0.02 wt.% max.
- 3. A billet as recited in claim 1 wherein:
- the amount of MnTe microinclusions is sufficient to cause surface checking during hot-deforming at temperatures substantially exceeding 1035.degree. C. (1900.degree. F.).
- 4. A billet as recited in claim 3 wherein:
- said composition contains no lead.
Parent Case Info
This is a continuation, of application Ser. No. 122,283, filed Feb. 19, 1980, now abandoned in turn a division of application Ser. No. 5,965 filed Jan. 24, 1979, U.S. Pat. No. 4,236,939.
US Referenced Citations (8)
Foreign Referenced Citations (4)
Number |
Date |
Country |
2107525 |
Aug 1972 |
DEX |
47-206 |
Nov 1972 |
JPX |
1020535 |
Feb 1966 |
GBX |
1357387 |
Jun 1974 |
GBX |
Divisions (1)
|
Number |
Date |
Country |
Parent |
5965 |
Jan 1979 |
|
Continuations (1)
|
Number |
Date |
Country |
Parent |
122283 |
Feb 1980 |
|