Shank or back material for high speed steel tools

Claim 2

IN A TOOL INCLUDING A TOOL PORTION OF KNOWN HIGH SPEED STEEL MATERIAL AND A SHANK OR BACK PORTION WELDED TO SAID TOOL PORTION, THE IMPROVEMENT COMPRISING SAID SHANK OR BACK PORTION BEING OF STEEL MATERIAL CONSISTING OF 0.2-0.6% OF CARBON, 3.0-7.0% OF CHROMIUM, 0.1-1.0% OF VANADIUM 0-0.3% OF NIOBUIM, NOT MORE THAN 0.8% OF SILICON, NOT MORE THAN 0.8% OF MANGANESE AND THE REMAINDER OF IRON AND INEVITABLE IMPURITIES, WHEREIN SAID STEEL MATERIAL OF SAID SHANK OR BACK PORTION PREVENTS DECARBURIZATION OR CEMENTATION IN THE WELD BETWEEN SAID SHANK OR BACK PORTION AND SAID TOOL PORTION RESPECTIVELY, SAID SHANK OR BACK PORTION MAINTAINING ITS TOUGHNESS WHEN THE TOOL IS SUBJECTED TO HEAT TREATMENT AT HIGH TEMPERATURES, AND SAID STEEL MATERIAL OF THE SHANK OR BACK PORTION HAVING AN HRC HARDNESS OF MORE THAN 40 WHEN SUBJECTED TO SAID HEAT TREATMENT UNDER THE SAME TEMPERING CONDITIONS AS FOR SAID HIGH SPEED STEEL TOOL PORTION, SAID STEEL MATERIAL OF THE SHANK OR BACK PORTION HAVING GOOD, CRACK-FREE WELDABILITY WITH SAID HIGH SPEED TOOL PORTION.

Claim 3

In a tool including a tool portion of a known high speed steel material and a shank or back portion welded to said tool portion, the improvement comprising said shank or back portion being of a steel material consisting of 0.2-0.6% of carbon, 3.0-7.0% of chromium, 0.1-1.0% of vanadium, 0.02-0.3% of niobium, not more than 0.8% of silicon, not more than 0.8% of manganese and the remainder of iron and inevitable impurities, wherein said steel material of said shank or back portion prevents decarburization or cementation in the weld between said shank or back portion and said tool portion respectively, said shank or back portion maintaining its toughness when the tool is subjected to heat treatment at high temperatures, and said steel material of the shank or back portion having an HRC hardness of more than 40 when subjected to said heat treatment under the same tempering conditions as for said high speed steel tool portion, said steel material of the shank or back portion having good, crack-free weldability with said high speed steel tool portions.

Claim 4

In a tool including a tool portion of a known high speed steel material and a shank or back portion welded to said tool portion, the improvement comprising said shank or back portion being of a steel material consisting of 0.2-0.6% of carbon, 3.0-7.0% of chromium, 0.1-1.0% of vanadium, 0.02-0.3% of niobium, not more than 0.8% of silicon, not more than 0.8% of manganese and the remainder of iron and inevitable impurities, wherein said steel material of said shank or back portion prevents decarburization or cementation in the weld between said shank or back portion and said tool portion respectively, said shank or back portion maintaining its toughness when the tool is subjected to heat treatment at high temperatures, and said steel material of the shank or back portion having an HRC hardness of more than 40 when subjected to said heat treatment under the same tempering conditions as for said high speed steel tool portion, said steel material of the shank or back portion having good, crack-free weldability with said high speed steel tool portions.

Claim 5

A tool according to claim 2, wherein said steel material has a composition consisting of 0.3-0.4% of carbon, 4.0-6.0% of chromium, 0.2-0.5% of vanadium, 0.02-0.3% of niobium, not more than 0.8% of silicon, not more than 0.8% of manganese and the remainder of iron and inevitable impurities.

Claim 6

A tool according to claim 2, wherein said steel material has a composition consisting of 0.3-0.4% of carbon, about 5% of chromium, 0.2-0.3% of vanadium, 0.09-0.3% of niobium, not more than 0.2% of silicon, not more than 0.3% of manganese and the remainder of iron and inevitable impurities.

Claim 7

A tool according to claim 1, wherein said steel material has a composition consisting of 0.3-0.4% of carbon, 3-7% of chromium, 0.2-0.3% of vanadium, not more than 0.2% of silicon, not more than 0.3% of manganese and the remainder of iron and inevitable impurities.