Effect of Preheat on Improving Beneficial Surface Residual Stresses During Induction Hardening Process

Abstract

Applications of the induction hardening process have been gradually increasing in the heat treatment industry due to its energy efficiency, process consistency, and clean environment. Compared to traditional furnace heating and liquid quenching processes, induction hardening is more flexible in terms of process control, and it can offer improved part quality. The commonly modified parameters for the process include the inductor power and frequency, heating time, spray quench delay and quench severity, etc. In this study, a single shot induction hardening process of a cylindrical component made of AISI 4340 is modeled using DANTE ® . It is known that the residual stresses in a hardened steel component have a significant effect on high cycle fatigue performance, with higher magnitudes of surface residual compression leading to improved high cycle fatigue life. Induction hardening of steel components produces surface residual compression due to the martensitic transformation of the hardened surface layer, with a high magnitude of compression preferred for improved performance in general. In this paper, a preheat concept is proposed with the induction hardening process for enhanced surface residual compression in the hardened case. Preheating can be implemented using either furnace or low power induction heating, and both processes are modeled using DANTE to demonstrate its effectiveness. With the help of computer modeling, the reasons for the development of residual stresses in an induction hardened part are described, and how the preheat can be used to improve the magnitude of surface residual compression is explained.

A influência de diferentes taxas de resfriamento de polímero PAG nas distorções em peças de aço SAE 1050 no tratamento térmico de têmpera por indução

“…A profundidade da camada temperada pode variar de 0,25 a 1 mm para rolamentos e eixos de bombas que necessitam de resistência ao desgaste, enquanto é desejada na ordem de 1-2,5 mm para virabrequins e eixos de comando que também necessitam de maior resistência [8]. A têmpera por indução é mais flexível com relação ao controle dos parâmetros de processo, tais como potência, frequência, tempo de aquecimento e resfriamento, podendo proporcionar melhor qualidade à peça temperada e redução de distorções [9].…”

“…Diversos estudos têm sido realizados com a alteração de parâmetros do processo de têmpera por indução e verificação das distorções e tensões residuais em diversos aços carbono e aços liga. Dentre estes parâmetros alterados podem ser citados o tempo de aquecimento [10], a intensidade da corrente elétrica do indutor no aquecimento [7], a adição de um pré-aquecimento na peça antes do tratamento térmico [9] a taxa de resfriamento da peça por spray [11] e o meio de resfriamento [6].…”

Induction Hardening Process With Preheat to Eliminate Cracking and Improve Quality of a Large Part With Various Wall Thickness

“…If the OD surface or the part body is heated to a temperature without affecting its metallurgical phase prior to induction heating, the thermal shrinkage of the body once martensitic transformation is complete can squeeze the bore and change its stress state. The preheat process prior to induction hardening can be implemented by either furnace heating or induction heating with low power [10,11]. In this study, the part is preheated to 200° C in a furnace, and the power applied to the inductor during hardening process is reduced to maintain the same case depth, while the frequency of the inductor remains the same.…”

Data-Driven Inverse Problem for Optimizing the Induction Hardening Process of C45 Spur-Gear

“…As a result, a fine-grained martensite phase [4][5][6] and a compressive residual stress field [7][8][9] are induced in the surface layer, which enhances the fatigue life behavior of engineering components [10,11]. However, high temperatures coupled with longer heat time could lead to grain growth (causing a degradation in fatigue strength), data scatter, and excessive gear distortion [12,13]. Accordingly, the control of the process parameters is highly important to validate the effectiveness of this heat treatment process [14].…”