Effects of Induction Hardening Process

induction hardening equipment machine

Monotonic torsional strength of induction hardening shafts is greatly influenced by the depth and hardness of the case, as well as the hardness of the core, as was shown by Ochi and Koyasu (Ref 1). Figure 1 shows that as case depth and carbon content increase, torsional strength increases. Likewise, as hardness increases, whether in the core or in the case, torsional strength increases, as shown in Fig. 2. This effect is also shown for varying case depths. Cost reduction measures in manufacturing industries, particularly within the automotive industry, have led to reduced material consumption and elimination of processing steps where possible. With the addition of small amounts of vanadium, niobium, and/or titanium, microalloyed steels provide high strength with a minimum of heat treatment processing (Ref 2). Material costs are reduced due to the lowering of alloy additions, and processing costs are reduced due to the elimination of heat treating steps. Microalloyed, medium carbon steels gain their strength from the precipitation of carbonitrides during cooling after austenitization. Strengths typical of highly tempered martensitic steels are obtained by pearlite formation and precipitation strengthening. Toughness is low, but can be increased by grain size refinement or by limiting alloy carbon content (Ref 2-5). Because the strengthening effects are exhibited in the directcooled, ferritic-pearlitic microstructures, heat treatment subsequent to rolling or forging is not necessary (Ref 2). High core strength provides a means of increasing performance of induction hardened shafts, and microalloying is one method used to increase the core strength.Also, because strength increases directly with the amount of cold work (Ref 6), it may be possible to use cold reduction concurrently with microalloying to provide a core with high strength.

Induction hardening depth

Effects of Induction Hardening Process.pdf