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US 5,411,613 AGranted
Method of making heat treated stainless steel needles
AssigneeUnited States Surgical Corporation
InventorsSaid Rizk, William O. Powers, W. Scott Samsel
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Abstract
Surgical needles are produced from martensitic precipitation-hardening stainless steel and then vacuum heat treated and vacuum cooled to increase its tensile strength while retaining the polished surface of the needle. A needle made by this process is also disclosed.
Claims20
A process for using martensitic precipitation hardening stainless steel to make surgical needles comprising the steps of:
- forming needle blanks consisting essentially of martensitic stainless steel into surgical needles by at least one step selected from the group consisting of sharpening a first end to be pointed, tapering, bending, and drilling a hole into a second end of said needle blank;
- heating said surgical needles under vacuum at a temperature in the range from about 350.degree. C. to about 550.degree. C. for a time in the range from about 15 minutes to about 20 hours;
- cooling said heated surgical needles in the absence of oxygen from said heating temperature to a temperature in the range from about 150.degree. C. to about ambient temperature, whereby said heating step hardens the surgical needle subsequent to said forming step.
A process for making surgical needles, comprising:
- a) providing needle blanks consisting essentially of martensitic precipitation hardening stainless steel,
- b) forming said needle blanks into surgical needles, then
- c) hardening said surgical needles by heating said surgical needles under vacuum at a temperature in the temperature range of from about 350.degree. C. to about 550.degree. C. for a period of time in the range of from about 15 minutes to about 20 hours, and then
- d) cooling said heated surgical needles in the absence of oxygen from said heating temperature to a temperature in the range of from about 150.degree. C. to about ambient temperature.
1 more element
Dependencies are inferred from the claim text.