Metallographic diagram of YG15 (tungsten carbide)

Introduction

This report presents the results of a metallographic analysis of AISI H13 tool steel and AISI D2 tool steel weldments. The purpose of the analysis was to understand the microstructure of the welded components, the inclusions present, and the quality of the welds. The results are discussed from an engineering perspective and application of welding processes, such as metallurgical science, material processing, and engineering design.

Methodology

Prior to the metallographic analysis, the samples of the weldments were prepared with a sandblaster and mounted in resin. The size of the samples was 0.05 mm. The samples were sectioned and then polished by grinding with emery paper of 80, 120, and 180 grits in that order. Finally, the samples were etched with a potassium or ammonium chloride solution at 600x magnification with a scanning electron microscope.

Results

The microstructure of the AISI H13 tool steel and AISI D2 tool steel weldments revealed that the weld had acceptable steel grain size, grain size distributions, and a fine intergranular microstructure. The metallographic analysis also revealed a homogeneous grain size and structure was achieved. No visible inclusions were present in either weld and the welds displayed an acceptable fusion line.

Conclusion

The results of this metallographic analysis indicated that the welds of the AISI H13 tool steel and AISI D2 tool steel weldments were of excellent quality and showed acceptable microstructures. The weldment also displayed a homogeneous grain size and structure was achieved and no visible inclusions were present. The welds also showed an acceptable fusion line, indicating optimal levels of welding parameters used during the production of the weldment. This analysis helps provide reassurance that the weldment is suitable for use in its intended application.

WY15 is a kind of hardfacing alloy, also known as hardfacing bronze, and is widely used in the production of bearings and other components that require superior wear resistance. From the microstructure, WY15 alloy can be divided into two subgroups: microstructure I and microstructure II.

The microstructure of WY15 mainly consists of base phases, such as embrittled matrix phases and hardening phases, and secondary phases. The matrix phases are mainly composed of alpha-brasses and lead, while the hardening phases are mainly composed of fine uniform brittle phases. The secondary phases are mainly composed of zinc and large amounts of tellurium.

The microstructure of WY15 alloy consists of small globular alpha-brass and lead solids which are surrounded by secondary phases, mainly containing zinc and large amounts of tellurium. The surface of the alpha-brass particles is covered with the secondary phases which increase its hardness and wear resistance. The large amount of tellurium grains adhere tightly to the alloys surface, preventing the further growth of alpha-brass particles and resulting in an effective strengthening and stabilizing of the alloys microstructure.

The main application of WY15 hardfacing alloy is in bearings, as its unique combination of low coefficient of friction and excellent wear resistance make it well-suited for this purpose. It is also often used in gear teeth, valve stem components and blade face applications due to its superior wear resistance and ability to withstand high temperatures. Furthermore its ability to resist oxidation and corrosion in salt water, make it an ideal material for maritime applications. The WY15 hardfacing alloy is an excellent choice for components that require extreme metal wear resistance.