Lead free steel and method of manufacturing

Patent metadata

Field	Value
Publication number	US-2016333451-A1
Application number	US-201615153455-A
Country	US
Kind code	A1
Filing date	May 12, 2016
Priority date	May 15, 2015
Publication date	Nov 17, 2016
Grant date	—

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 steel product that is essentially lead free, wherein the steel product comprises:
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 0.4 to 0.12 wt-%; or
bismuth in a range of 0.01 to 0.15 wt-%;
balance being Fe and normally occurring scrap steel impurities; and wherein the steel product is subjected to a heat treatment process during which the steel product is subjected to:
a first temperature for a first duration;
a second temperature for a second duration, wherein the second temperature is less than the first temperature;
a third temperature for a for a third time period, wherein the third temperature is greater than the second temperature; and
cooled after the third temperature.

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

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

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

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

6 . The steel product 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.

7 . The steel product of claim 1 , wherein the first temperature ranges between 1500-1800 degrees F., the second temperature ranges between 1000-1300 degrees F., and the third temperature ranges between 1100-1400 degrees F.

8 . The steel product of claim 7 , wherein the first temperature ranges between 1590-1690 degrees F., the second temperature ranges between 1100-1200 degrees F., and the third temperature ranges between 1200-1300 degrees F.

9 . The steel product of claim 1 , wherein a microstructure of the steel product comprises lamellar perlite.

10 . The steel of claim 9 , wherein the microstructure comprises at least 75% lamellar perlite.

11 . A method for manufacturing an essentially lead free steel, the method comprising:
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; 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 0.4 to 0.12 wt-%; or
bismuth in a range of 0.01 to 0.15 wt-%; and

balance being Fe and normally occurring scrap steel impurities.

12 . The method of claim 11 , wherein the composition comprises only the tellurium, and wherein the tellurium is in a range of 0.003 to 0.090 wt-%.

13 . The method of claim 11 , wherein the composition comprises only the selenium, and wherein the selenium is in a range of 0.080 to 0.20 wt-%.

14 . The method of claim 11 , wherein the composition comprises only the sulfur, and wherein the sulfur is in a range of 0.065 to 0.090 wt-%.

15 . The method of claim 11 , wherein the composition comprises only the bismuth, and wherein the bismuth is in a range of 0.03 to 0.1 wt-%.

16 . The method of claim 11 , 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.

17 . The method of claim 11 , wherein the first temperature ranges between 1500-1800 degrees F., the second temperature ranges between 1000-1300 degrees F., and the third temperature ranges between 1100-1400 degrees F.

18 . The method of claim 17 , wherein the first temperature ranges between 1590-1690 degrees F., the second temperature ranges between 1100-1200 degrees F., and the third temperature ranges between 1200-1300 degrees F.

19 . The method of claim 11 , wherein a microstructure of the steel product comprises lamellar perlite.

20 . The method of claim 19 , wherein the microstructure comprises at least 75% lamellar perlite.

21 . A steel product that is essentially lead free, wherein the steel product comprises:
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 0.4 to 0.12 wt-%; or
bismuth in a range of 0.01 to 0.15 wt-%;
balance being Fe and normally occurring scrap steel impurities.

22 . A method for a heat treatment process, the method comprising:
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, wherein the first temperature ranges between 1500-1800 degrees F.;
the steel product is subjected to a second temperature for a second duration,
wherein the second temperature ranges between 1000-1300 degrees F., and 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 ranges between 1100-1400 degrees F., and wherein the third temperature is greater than the second temperature; and cooling the steel product.

Assignees

• Nucor Corp

Inventors

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

Classifications

• C22C38/22

  with molybdenum or tungsten · CPC title

• C22C38/02

  containing silicon · CPC title

• C22C38/48

  with niobium or tantalum · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C22C38/50

  with titanium or zirconium · CPC title