INFLUENCE THE QUENCHING AND TEMPERING ON THE MICROSTRUCTURE, MECHANICAL PROPERTIES AND SURFACE ROUGHNESS, OF MEDIUM CARBON STEEL

2018 ◽  
Vol 18 (1) ◽  
pp. 125-135
Author(s):  
Sattar H A Alfatlawi

One of ways to improve properties of materials without changing the product shape toobtain the desired engineering applications is heating and cooling under effect of controlledsequence of heat treatment. The main aim of this study was to investigate the effect ofheating and cooling on the surface roughness, microstructure and some selected propertiessuch as the hardness and impact strength of Medium Carbon Steel which treated at differenttypes of heat treatment processes. Heat treatment achieved in this work was respectively,heating, quenching and tempering. The specimens were heated to 850°C and left for 45minutes inside the furnace as a holding time at that temperature, then quenching process wasperformed in four types of quenching media (still air, cold water (2°C), oil and polymersolution), respectively. Thereafter, the samples were tempered at 200°C, 400°C, and 600°Cwith one hour as a soaking time for each temperature, then were all cooled by still air. Whenthe heat treatment process was completed, the surface roughness, hardness, impact strengthand microstructure tests were performed. The results showed a change and clearimprovement of surface roughness, mechanical properties and microstructure afterquenching was achieved, as well as the change that took place due to the increasingtoughness and ductility by reducing of brittleness of samples.

2012 ◽  
Vol 531-532 ◽  
pp. 596-599
Author(s):  
Kai Zhang ◽  
Shang Wen Lu ◽  
Yao Hui Ou ◽  
Xiao Dong Wang ◽  
Ning Zhong

The recently developed “quenching and partitioning” heat treatment and “quenching-partitioning-tempering” heat treatment are novel processing technologies, which are designed for achieving advanced high strength steels (AHSS) with combination of high strength and adequate ductility. In present study, a medium carbon steel containing Nb was subjected to the Q-P-T process, and both the microstructure and mechanical properties was studied. The experimental results show that the Nb-microalloyed steel demonstrates high tensile strength and relatively high elongation. The microstructure of the steel was investigated in terms of scanning electron microscope and transmission electron microscope, and the results indicate that the Q-P-T steel consist of fine martensite laths with dispersive carbide precipitates and the film-like interlath retained austenite. The orientation relationships between martensite and retained austenite is as well-known Kurdjurmov-Sachs relationship and Nishiyama-Wasserman relationship.


2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Yan Peng ◽  
Caiyi Liu ◽  
Ningning Wang

AbstractThe current research of the Q-P and Q-P-T process has been focused on controlling the heating temperature and holding time, or adding alloy elements into the steel to induce precipitation strengthening and improve the strength and plasticity of the steel. In this article, based on a quenching-partitioning-tempering (Q-P-T) process combined with a hot deformation technology, a deforming-quenching-partitioning-tempering (D-Q-P-T) process was applied to medium carbon steel. The effect of the heat treatment parameters on the microstructure and mechanical properties of experimental steel under deformation was studied. Through use of a scanning electron microscope (SEM), transmission electron microscopy (TEM) and tensile tests, the optimal heat treatment conditions for realizing high strength and plasticity that meet the safety requirements were obtained. The mechanism for the D-Q-P-T process to improve the strength and plasticity of experimental steel was discussed. A multiphase composite structure of lath martensite and retained austenite was obtained. Compared with the Q-P-T process, use of the D-Q-P-T process can increase the strength of steel by 57.77 MPa and the elongation by 5%. This study proposes a method to improve the strength and plasticity of steel.


2013 ◽  
Vol 315 ◽  
pp. 6-10 ◽  
Author(s):  
S.M. Manladan ◽  
B.O. Onyekpe

This paper presents the result of an investigation of the effect of postweld heat treatment on the mechanical properties of weld in 0.36%C medium Carbon Steel. Samples were prepared and welded using Shielded Metal Arc Welding (SMAW) process with a low hydrogen electrode. The welded samples were subjected to postweld heat treatment (stress relief) at four different temperatures: 550°C, 600°C, 650°C and 700°C followed by air-cooling. Microstructural examination was carried out to determine the change in microstructure before and after postweld heat treatment. The mechanical properties of the samples were also tested before and after the heat treatment. It was established that a hard microstructure, susceptible to Hydrogen Induced Cracking (HIC), was formed in the heat affected zone of the as-welded samples and that postweld heat treatment improved the mechanical properties of the weld and substantially reduced or eliminated the risk of HIC.


Author(s):  
R. Suresh

The effect of various heat treatment operations (annealing, normalizing and hardening) on mechanical properties of medium carbon steel was investigated. The samples were prepared and heat-treated at 770 ºC subsequently was cooled by different quenching media. The mechanical properties of the treated and untreated samples were determined using standard methods. Results showed that the mechanical properties of carbon steel can be changed and improved by various heat treatments. It was also found that the annealed samples has the lowest tensile strength and hardness value and highest ductility, while hardened samples has the highest tensile strength and hardness value and lowest ductility value.


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