Method for exposing surface defects on hot steel blanks
AssigneeEschweiler Bergwerks-Verein Aktiengesellschaft
InventorKlaus Glomb
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Abstract
The present method makes it possible to expose or make visible surface defects on or in the surface of steel blanks by heating the blanks to a temperature below the hot working temperature of the particular type of steel and thereafter rapidly descaling the blanks by means of high pressure water which contacts the steel for a limited time so as to avoid a substantial chilling or quenching. After such descaling the blanks are cooled at a controlled rate to thereby produce an oxidation film on the descaled surface which film makes the defects visible.
Claims5
A method for exposing surface defects on steel blanks having a given hot working temperature, comprising the following steps:
- a. employing blanks heated to a temperature within the range of about 500.degree. to 1100.degree.C whereby such temperature is kept below said given hot working temperature of the particular steel blank,
- b. rapidly descaling the heated blank by exposing the heated blank to cold water under pressure within the range of about 100 atm to 500 atm (gauge) thereby limiting the exposing to a duration of about 1.10.sup..sup.-4 seconds to 3.10.sup..sup.-2 seconds so that any substantial chilling of the blank is avoided, and
- c. controlling the cooling of the thus descaled blank with a cooling rate within the range of about 10.degree.C/minute to about 100.degree.C/minute, to thereby produce an oxidation film on the descaled surface which oxidation film makes said surface defects visible.
Dependencies are inferred from the claim text.