Lead free steel and method of manufacturing

Patent metadata

Field	Value
Publication number	US-10400320-B2
Application number	US-201615153455-A
Country	US
Kind code	B2
Filing date	May 12, 2016
Priority date	May 15, 2015
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

An essentially lead free steel having, in percent by weight (wt-%): Carbon: 0.39-0.43%; Manganese: 0.75-1.00%; Silicon: 0.15-0.35%; Chromium: 0.80-1.05%; Molybdenum: 0.15-0.25%; at least one of Tellurium: 0.003-0.090 wt-%, Selenium: 0.080-0.2 wt-%, Sulfur: 0.065-0.09% wt-%, and Bismuth: 0.03-0.1 wt-%; and the balance being Fe and normally occurring scrap steel impurities. A method for manufacturing an essentially lead free steel by subjecting a hot-rolled steel product to a heat treatment in which the steel product is subjected to a first temperature for a first duration; the steel product is subjected to a second temperature for a second duration, wherein the second temperature is less than the first temperature; and the steel product is subjected to a third temperature for a third time period, wherein the third temperature is greater than the second temperature; and cooling the steel product. After the heat treatment the steel is cold worked to the desired size.

First claim

What is claimed is:

1. A method for manufacturing an essentially lead free steel, the method comprising:
subjecting a hot rolled steel product to an annealing heat treatment in which
the steel product is subjected to a first temperature for a first duration;
the steel product is subjected to a second temperature for a second duration, wherein the second temperature is less than the first temperature; and
the steel product is subjected to a third temperature for a third duration, wherein the third temperature is greater than the second temperature, and wherein an increase from the second temperature to the third temperature occurs over a duration that is greater than or equal to 5 minutes;

cooling the steel product; and
wherein the steel product comprises the following composition:
carbon in a range of 0.2 to 0.6 wt-%;
manganese in a range of 0.6 to 1.1 wt-%;
silicon in a range of 0.1 to 0.4 wt-%;
chromium in a range of 0.6 to 1.2 wt-%;
molybdenum in a range of 0.1 to 0.3 wt-%;
at least one or more of:
tellurium in a range of 0.001 to 0.12 wt-%;
selenium in a range of 0.05 to 0.25 wt-%;
sulfur in a range of 0.04 to 0.12 wt-%; or
bismuth in a range of 0.01 to 0.15 wt-%; and

balance being Fe and unavoidable impurities; and

wherein a microstructure of the steel product comprises lamellar perlite.

2. The method of claim 1 , wherein the composition comprises the tellurium, and wherein the tellurium is in the range of 0.003 to 0.090 wt-%.

3. The method of claim 1 , wherein the composition comprises the selenium, and wherein the selenium is in the range of 0.080 to 0.20 wt-%.

4. The method of claim 1 , wherein the composition comprises the sulfur, and wherein the sulfur is in the range of 0.065 to 0.090 wt-%.

5. The method of claim 1 , wherein the composition comprises the bismuth, and wherein the bismuth is in the range of 0.03 to 0.1 wt-%.

6. The method of claim 1 , wherein at the first temperature the steel product is in an austenitic phase, wherein at the second temperature and the third temperature the steel product is in a pearlitic/ferritic phase, and wherein in at the third temperature is greater than the second temperature.

7. The method of claim 1 , wherein the first temperature ranges between 1425-1800 degrees F. and wherein the first duration ranges from 15 mins to 5.75 hours, the second temperature ranges between 1000-1300 degrees F. and wherein the second duration ranges from 1 min to 85 mins, and the third temperature ranges between 1100-1400 degrees F. and wherein the third duration ranges from 15 to 130 mins.

8. The method of claim 1 , wherein the microstructure comprises at least 75% lamellar perlite.

9. A method for manufacturing an essentially lead free steel, the method comprising:
subjecting a hot rolled steel product to an annealing heat treatment in which
the steel product is subjected to a first temperature for a first duration;
the steel product is subjected to a second temperature for a second duration, wherein the second temperature is less than the first temperature; and
the steel product is subjected to a third temperature for a third duration, wherein the third temperature is greater than the second temperature, and wherein an increase from the second temperature to the third temperature occurs over a duration that is greater than or equal to 5 minutes;

cooling the steel product; and
wherein the steel product comprises the following composition:
carbon in a range of 0.2 to 0.6 wt-%;
manganese in a range of 0.6 to 1.1 wt-%;
silicon in a range of 0.1 to 0.4 wt-%;
chromium in a range of 0.6 to 1.2 wt-%;
molybdenum in a range of 0.1 to 0.3 wt-%;
sulfur in the range of 0.065 to 0.090 wt-%; and
balance being Fe and unavoidable impurities.

10. The method of claim 9 , wherein at the first temperature the steel product is in an austenitic phase, wherein at the second temperature and the third temperature the steel product is in a pearlitic/ferritic phase, and wherein in at the third temperature is greater than the second temperature.

11. The method of claim 9 , wherein the first temperature ranges between 1425-1800 degrees F. and wherein the first duration ranges from 15 mins to 5.75 hours, the second temperature ranges between 1000-1300 degrees F. and wherein the second duration ranges from 1 min to 85 mins, and the third temperature ranges between 1100-1400 degrees F. and wherein the third duration ranges from 15 to 130 mins.

12. The method of claim 9 , wherein a microstructure of the steel product comprises lamellar perlite.

13. A method for manufacturing an essentially lead free steel, the method comprising:
subjecting a hot rolled steel product to an annealing heat treatment in which
the steel product is subjected to a first temperature for a first duration, wherein the first temperature ranges between 1425-1800 degrees F. and wherein the first duration ranges from 15 mins to 5.75 hours;
the steel product is subjected to a second temperature for a second duration, wherein the second temperature is less than the first temperature, the second temperature ranges between 1000-1300 degrees F. and wherein the second duration ranges from 1 min to 85 mins; and
the steel product is subjected to a third temperature for a third duration, wherein the third temperature is greater than the second temperature, wherein an increase from the second temperature to the third temperature occurs over a duration that is greater than or equal to 5 minutes, wherein the third temperature ranges between 1100-1400 degrees F., and wherein the third duration ranges from 15 to 130 mins;

cooling the steel product; and
wherein the steel product comprises the following composition:
carbon in a range of 0.2 to 0.6 wt-%;
manganese in a range of 0.6 to 1.1 wt-%;
silicon in a range of 0.1 to 0.4 wt-%;
chromium in a range of 0.6 to 1.2 wt-%;
molybdenum in a range of 0.1 to 0.3 wt-%;
at least one or more of:
tellurium in a range of 0.001 to 0.12 wt-%;
selenium in a range of 0.05 to 0.25 wt-%;
sulfur in a range of 0.04 to 0.12 wt-%; or
bismuth in a range of 0.01 to 0.15 wt-%; and

balance being Fe and unavoidable impurities.

14. The method of claim 13 , wherein the composition comprises the tellurium, and wherein the tellurium is in the range of 0.003 to 0.090 wt-%.

15. The method of claim 13 , wherein the composition comprises the selenium, and wherein the selenium is in the range of 0.080 to 0.20 wt-%.

16. The method of claim 13 , wherein the composition comprises the sulfur, and wherein the sulfur is in the range of 0.065 to 0.090 wt-%.

17. The method of claim 13 , wherein the composition comprises the bismuth, and wherein the bismuth is in the range of 0.03 to 0.1 wt-%.

18. The method of claim 13 , wherein at the first temperature the steel product is in an austenitic phase, wherein at the second temperature and the third temperature the steel product is in a pearlitic/ferritic phase, and wherein in at the third temperature is greater than the second temperature.

19. The method of claim 13 , wherein the first temperature ranges between 1550-1690 degrees F. and wherein the first duration ranges from 20 mins to 310 mins, the second temperature ranges between 1100-1200 degrees F. and wherein the second duration ranges from 1 min to 80 mins, and the third temperature ranges between 1200-1300 degrees F. and wherein the third duration ranges from 20 mins to 115 mins.

20. The method of claim 19 , wherein a decrease from the first temperature to the second temperatur

Assignees

• Nucor Corp

Inventors

• Hicks Matthew J
• Hill Jim L
• Bugenhagen Brook C

Classifications

• C22C38/22

  with molybdenum or tungsten · CPC title

• C21D6/008

  containing Si · CPC title

• C22C38/008

  containing tin · CPC title

• C22C38/001

  containing N · CPC title

• C21D6/004

  containing Cr and Ni · CPC title