Combination carburizing and boronizing methods

The method of manufacturing steel articles requiring a strong and tough wear resistant surface, said method comprising the steps of:

• first, carburizing said surface in a carbon rich environment in a furnace at a time and temperature to produce a case depth of at least 0.030 inch;
• second, pack boronizing said carburized case in a boron compound in a furnace at a time and temperature to produce a boronized case to a depth of at least 0.001 inch;
• third, hardening said carburized case by quenching after heating to a temperature and cooling at a rate to produce martensite;
• and
• fourth, tempering said carburized case by heating to a temperature to produce tempered martensite;
• whereby the wear resistant boronized surface has a tough and strong supporting base to sustain large loads and avoid brittle fracture.

The method of manufacturing steel articles requiring a strong and tough wear resistant surface, said method comprising the steps of:

• first, carburizing said surface in a carbon rich environment in a furnace at a time and temperature to produce a carburized case of selected depth of at least 0.030 inch;
• second, pack boronizing said carburized case in a furnace with a compound of B.sub.4 C at a time and temperature to produce a depth of at least 0.001 inch;
• third, quenching said carburized case from a temperature to produce a martensitic grain structure;
• and
• fourth, tempering said carburized case to produce a tempered martensitic grain structure;
• whereby the wear resistant boronized surface has a tough and strong supporting base to sustain large loads and avoid brittle fracture.

The method of manufacturing steel articles requiring a strong and tough wear resistant surface, said comprising the steps of:

• first, carburizing said surface after said article has been finally formed at a time and temperature to produce a case depth of at least 0.030 inch;
• second, pack boronizing said carburized case in a furnace with a compound consisting essentially of B.sub.4 C and graphite at a time and temperature to produce a depth of at least 0.001 inch;
• third, quenching said carburized case from a temperature of at least 1390.degree. F. to produce a martensitic grain structure;
• and
• fourth, tempering said carburized case at a temperature of at least 290.degree. F. to produce a tempered martensitic grain structure;
• whereby the wear resistant boronized surface has a tough and strong supporting base to sustain large loads and avoid brittle fracture.

The method of manufacturing steel articles requiring a strong and tough wear resistant surface, said method comprising the steps of:

• first, carburizing said surface in a carbon rich environment at about 1700.degree. F. for about nine hours to produce a case depth of about 0.065 inch;
• second boronizing said carburized case by packing a boronizing powder consisting essentially of boron carbide and graphite around the carburized surface, and heating the article in a furnace having a non-oxidizing atmosphere at a temperature of about substantially 1650.degree. F. for about five hours to produce a depth of about 0.004 inch;
• third quenching said carburized case from a temperature of at least substantially 1390.degree. F. to produce a martensitic grain structure;
• and
• fourth tempering said carburized case from a temperature within a range of substantially 290.degree. F. through 510.degree. F. for about one hour to produce a tempered martensitic grain structure;
• whereby the wear resistant boronized surface has a tough and strong supporting base to sustain large loads and avoid brittle fracture.