Date of Award

Spring 2022

Degree Type

Thesis

Degree Name

Master of Materials Science and Engineering (MMatSE)

Department

Materials Science

Committee Chair

Sudhakar Vadiraja

First Advisor

Avimanyu Das

Second Advisor

Nathan Huft

Abstract

Heat treatment, tensile testing failure analysis, and microstructural evaluation of the Crucible Industries tool steel CPM® 3V was undertaken to investigate CPM® 3V’s tempering response for the following samples: As-Hardened (no tempering); tempered at 450°C, 550°C, 650°C, and 700°C; and As-Received (annealed). CPM® 3V tool steel is manufactured by Crucible Industries using their proprietary Crucible Particle Metallurgy (CPM®) technology. This material was heat-treated at four different tempering temperatures and was evaluated for tensile properties according to ASTM E8. A TMS landmark tensile fixture was used to establish the ultimate tensile strength and the yield strength of the material for the various heat-treated conditions. A detailed failure investigation of the fractured tool steel was carried out to assess the mode of fracture at various size scales. The test specimens and their fracture surfaces were subjected to detailed examination. Representative fracture surfaces were analyzed using a Tescan Mira scanning electron microscope (SEM) to determine the fracture morphology and material’s behavior at a microscopic scale. Microstructural characterization was done for all sample conditions using Leica reflected light microscopy and the Tescan Mira SEM to ascertain the microstructural changes in the material. Detailed investigations of the tool steel ASTM E8 standard tensile test specimens established the samples tempered at < 550°C were dominated by brittle failure while samples tempered at > 550°C experienced ductile failure. The 550°C treatment showed mixed ductile and brittle fracture features. This study found that CPM® 3V can be optimized for strength, with good tensile toughness, at a 550°C tempering temperature. This is consistent with the recommended tempering temperature for good wear resistance and toughness in Crucible Industries data sheet.

Comments

A thesis submitted in partial fulfillment of the requirements for the degree of M.S. in Materials Science and Engineering.

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