Improving the Mechanical Property of High Carbon Tool Steel with Isothermal Heat treatment
Date Issued
2004
Date
2004
Author(s)
Liu, Chia-Min
DOI
zh-TW
Abstract
The purpose of the present experiment is to improve the mechanical property （hardness、toughness and flatness）of carbon tool steel by modifying the conventional heat treatment processeses. The proposed heat treating process is isothermal heat treatment followed by a high-
temperature and short-time tempering, which is going to replace the traditional heat treatment of quenching and tempering. On condition that the flatness matches the requirement, the heat treatment parameter that affect the hardness and toughness are discussed. The best heat treatment process in the present experiment is reported for practical application. The results obtained are as follows:
1.For the traditional heat treatment （810℃ × 15 min Austenization → 120℃ × 1hr oil quenching → 1hr low-temperature tempering for 1 hr）, the critical bending angle of the specimen increases with the raising of temper temperature, but when the temperature is over 280℃, the critical angle will decrease. It’s because the martensite content of the specimen after traditional quenching was much more than that of the isothermal heat treatment specimen, so the Tempered Martensite Embrittlement effect was much more noticeable.
2.Either for the traditional quenching or isothermal heat treatment（Martempering、Austempering）, the mechanical property of specimen that tempered at 405℃ is better than that tempered at the temperature from 240℃ to 290℃.
3.If the temper temperature is lowered from 405℃ to 360℃, the tempering time will increase from 50sec to 2~3min, which is more feasible for practical heat treatment. By the comparisons of the critical bending angle at the same hardness level（Hv690）, the specimen which was tempered at 360℃ was inferior to that tempered at 405℃, but better than that tempered at 260℃.
4.The optimal heat treatment process of carbon tool steel in the present experimental condition is:810℃ × 15min Austenization → 140℃ × 1hr Martempering → 405℃ × 50sec Strengthening Tempering
Subjects
低溫回火脆性
恆溫熱處理
沃斯回火
麻回火
Isothermal Heat Treatment
Austemper
Tempered Embrittlement
Martemper
High Carbon Tool Steel
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-93-R91522717-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):ae0cc5c5b1daafa35976e8f5a66cf14d