Finite Element Analysis of Laser Engineered Net Shape (LENS™) Tungsten Clad Squeeze Pins

Abstract

Articles you may be interested inStudy of carbide dissolution into the matrix during laser cladding of carbon steel plate with tungsten carbidesstellite powders J. Laser Appl. 27, S29209 (2015); 10.2351/1.4906480 Effect of process parameters in laser cladding on substrate melted areas and the substrate melted shape A finite element method approach for thermal analysis of laser cladding of magnesium alloy with preplaced Al-Si powder J. Laser Appl. 16, 229 (2004); 10.2351/1.1809634 Three-dimensional finite element modeling of laser cladding by powder injection: Effects of powder feedrate and travel speed on the process J. Laser Appl. 15, 153 (2003);Abstract. In the aluminum high-pressure die-casting and indirect squeeze casting processes, local "squeeze" pins are often used to minimize internal solidification shrinkage in heavy casting sections. Squeeze pins frequently fail in service due to molten aluminum adhering to the H13 tool steel pins ("soldering"). A wide variety of coating materials and methods have been developed to minimize soldering on H13. However, these coatings are typically very thin, and experience has shown their performance on squeeze pins is highly variable. The LENS process was employed in this research to deposit a relatively thick tungsten cladding on squeeze pins. An advantage of this process was that the process parameters could be precisely controlled in order to produce a satisfactory cladding. Two fixtures were designed and constructed to enable the end and outer diameter (OD) of the squeeze pins to be clad. Analyses were performed on the clad pins to evaluate the microstructure and chemical composition of the tungsten cladding and the cladding-H13 substrate interface. A thermo-mechanical finite element analysis (FEA) was performed to assess the stress distribution as a function of cladding thickness on the pins during a typical casting thermal cycle. FEA results were validated via a physical test, where the clad squeeze pins were immersed into molten aluminum. Pins subjected to the test were evaluated for thermally induced cracking and resistance to soldering of the tungsten cladding.