Nitrided boron steel

• US 3,901,740 A
• Filed: 03/18/1974
• Issued: 08/26/1975
• Est. Priority Date: 05/12/1972
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Charles J. Anderson, David S. Gould
• Inventors: Anderson, Charles J., Gould, David S.
• Primary Examiner(s): Lovell, C.
• Application Number:
  US05/452,185
• Time in Patent Office: 526 Days
• Field of Search: 75/123B,123J 148/16.6,31.5,143
• US Class Current: 148/217
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60

Abstract

A method of economically producing steel parts having high case hardness and commensurate core properties, the parts being formed from low carbon steel containing about 0.25 to 0.50 percent of carbon, about 0.80 to 1.60 percent of manganese, about 0.40 maximum percent of silicon, about 0.0003 to 0.005 percent of boron, up to approximately 0.1 percent of a suitable nitriding agent such as vanadium, titanium tungsten, aluminum, zirconium, columbium, chromium or molybdenum, balance essentially iron, the boron and nitriding agent being in an uncombined or atomic form, the parts being hardened to develop desirable core properties and then being nitrided to develop case hardness.

Claims

1. A METHOD OF ECONOMICALLY PRODUCING STEEL PARTS HAVING HIGH CASE HARDNESS AND COMMENSURATE CORE PROPERTIES, COMPRISING THE STEPS OF FORMING THE STEEL PARTS FROM STEEL CONSISTING OF ABOUT 0.25 TO 0.50 PERCENT OF CARBON ABOUT 0.8 TO 1.60 PERCENT OF MANGANSESE, NORMAL IMPURITIES, ABOUT 0.0003 TO 0.005 PERCENT OF BORON, APPROXIMATELY 0.03 TO 0.05 PERCENT VANDIUM AS A NITRIDING AGENT, AND THE BALANCE IRON, THE BORON AND VANADIUM BEING PRESENT IN UNCOMBINED FORM, PRELIMINARILY HARDENING THE PARTS TO DEVELOP CORE TOUGHNESS, BEAM STRENGTH AND DEPTH HARDNESS, AND NITRIDING THE STEEL PARTS TO FORM A CASE HAVING A MINIMUM KNOOP HARDNESS OF APPROXIMATELY 400 TO A DEPTH OF APPROXIMATELY 0.012 INCHES.

2. Steel parts having high case hardness and commensurate core properties of core toughness, beam strength and depth hardness, the parts being produced by the steps of forming the parts from steel consisting of approximately 0.25 to 0.50 percent carbon, approximately 0.80 to 1.60 percent of manganese, normal impurities, approximately 0.0003 to 0.005 percent of boron, approximately 0.03 to 0.05 percent vanadium as a nitriding agent and the balance iron, the boron and vanadium being present in uncombined form, the parts being initially hardened to develop desirable core properties and subsequently nitrided to develop a minimum Knoop case hardness of approximately 400 to a depth of approximately 0.012 inches.