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Paper Information

Journal:   MODARES TECHNICAL AND ENGINEERING   SUMMER 2007 , Volume - , Number 28 (SPECIAL ISSUE ON MECHANICAL ENGINEERING); Page(s) 1 To 15.
 
Paper: 

HARDFACING OF H11 (1.2343) HOT WORK TOOL STEEL WITH THE SUPERALLOY STELLITE 6

 
 
Author(s):  KAVOUSI SISI M., MALEK GHAYENI F.*
 
* DEPARTMENT OF ENGINEERING MATERIALS, TARBIAT MODARES UNIVERSITY, TEHRAN, IRAN
 
Abstract: 

Thermal fatigue (heat checking), mechanical fatigue, wear and plastic deformation of critical areas of hot forging dies at working temperatures are the main mechanisms that reduce their lifetime. During forging processes the surfaces of the dies reach temperatures of 700-800°C.
Therefore, hardfacing of these areas with nonferrous elevated temperature hardfacing alloys such as Stellite 6 can improve the performance and lifetime of the dies, many times. Hot hardness, galling resistance, hot corrosion and oxidation resistance, adhesive wear resistance, low friction coefficient and absence of allotropic transformation up to 1100
°C are the most important properties of Stellite 6. H11 tool steel is widely used as hot forging die material. This steel because of its high alloy contents and, therefore, its hardenability is very sensitive to high cooling rates involved during welding cycles and hydrogen induced cracking (HIC). For this reason, in this research hardfacing parameters of Hl1 tool steel with Stellite 6 in TIG welding method have been investigated. According to the results, hardfacing of this steel in annealed hardfaced condition isn't feasible and it is recommended that preheating and intermediate temperatures during the hardfacing cycle between 310-370°C. The suitable current for TIG hardfacing of this steel by jp3.2 mm filler rod was determined to be 80-85 amperes for the first layer and 90-100 amperes for upper layers. The minimum thickness for obtaining maximum hardness in the hard facing layer (41-42 HRC) under these conditions was determined to be 3mm. It is recommended that the effective heat input for hardfacing of this steel under three-body heat transfer conditions would be less than 455kJ/m. It is also recommended that the Dt8®5 of H11 tool steel hardfacing cycle would be in the range 6 to 15.3s. Finally it is recommended that H11 hardfaced tool steel would be stress relived in the range 425 -500°C for 1 hour per 30mm base metal thickness.

 
Keyword(s): HARDFACING, STELLITE 6 HARDFACING SUPERALLOY, H11 HOT WORK TOOL STEEL, 1.2343 HOT WORK TOOL STEEL, HOT FORGING DIES, HOT HARDNESS, WELDABILITY
 
References: 
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