Abstract
Steels with good machinability are required for the ever-increasing demand for machining efficiency in industry. The manganese sulfide (MnS) inclusions in lead-free resulfurized free-cutting steels act as stress raisers, lowering the shear strength of steel such that the cutting resistance is reduced. Because the morphology of MnS critically determines the machinability of steels, the reactions involving the formation of MnS during solidification need to be carefully assessed, especially with regard to whether they are eutectic or monotectic reactions. In this paper, we established the relationships between alloying elements and solidified microstructures by utilizing both the CALPHAD-type thermodynamic modeling and high-temperature experiments at 1600 °C. The effects of sulfur content on the MnS microstructure were evaluated based on the solidification paths of the ideal iron-manganese-sulfur ternary system as well as the realistic iron-manganese-sulfur-silicon-carbon quinary system. Moreover, we systematically evaluated the effects of various alloying elements, namely hydrogen, boron, carbon, nitrogen, oxygen, aluminum, silicon, phosphor, argon, vanadium, chromium, cobalt, nickel, copper, arsenic, zirconium, niobium, molybdenum, tin, tantalum, tungsten, on the microstructure of MnS. Among those, oxygen is identified as a super-strong monotectic-stabilizer, and the addition of oxygen can drastically enhance the monotectic-type MnS, which is desirable for free-cutting steels. The thermodynamic predictions agree closely with experiments. With the combined efforts of thermodynamic calculations and high-temperature experiments, the morphology, size, and uniformity of MnS inclusions can be optimized for the development of better free-cutting steels.
| Original language | English |
|---|---|
| Pages (from-to) | 844-855 |
| Number of pages | 12 |
| Journal | Journal of Alloys and Compounds |
| Volume | 779 |
| DOIs | |
| Publication status | Published - 2019 Mar 30 |
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All Science Journal Classification (ASJC) codes
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry
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CALPHAD-assisted morphology control of manganese sulfide inclusions in free-cutting steels. / Lin, Shih guei; Yang, Hung hua; Su, Yen hao; Chang, Ku ling; Yang, Chih han; Lin, Shih-kang.
In: Journal of Alloys and Compounds, Vol. 779, 30.03.2019, p. 844-855.Research output: Contribution to journal › Article
TY - JOUR
T1 - CALPHAD-assisted morphology control of manganese sulfide inclusions in free-cutting steels
AU - Lin, Shih guei
AU - Yang, Hung hua
AU - Su, Yen hao
AU - Chang, Ku ling
AU - Yang, Chih han
AU - Lin, Shih-kang
PY - 2019/3/30
Y1 - 2019/3/30
N2 - Steels with good machinability are required for the ever-increasing demand for machining efficiency in industry. The manganese sulfide (MnS) inclusions in lead-free resulfurized free-cutting steels act as stress raisers, lowering the shear strength of steel such that the cutting resistance is reduced. Because the morphology of MnS critically determines the machinability of steels, the reactions involving the formation of MnS during solidification need to be carefully assessed, especially with regard to whether they are eutectic or monotectic reactions. In this paper, we established the relationships between alloying elements and solidified microstructures by utilizing both the CALPHAD-type thermodynamic modeling and high-temperature experiments at 1600 °C. The effects of sulfur content on the MnS microstructure were evaluated based on the solidification paths of the ideal iron-manganese-sulfur ternary system as well as the realistic iron-manganese-sulfur-silicon-carbon quinary system. Moreover, we systematically evaluated the effects of various alloying elements, namely hydrogen, boron, carbon, nitrogen, oxygen, aluminum, silicon, phosphor, argon, vanadium, chromium, cobalt, nickel, copper, arsenic, zirconium, niobium, molybdenum, tin, tantalum, tungsten, on the microstructure of MnS. Among those, oxygen is identified as a super-strong monotectic-stabilizer, and the addition of oxygen can drastically enhance the monotectic-type MnS, which is desirable for free-cutting steels. The thermodynamic predictions agree closely with experiments. With the combined efforts of thermodynamic calculations and high-temperature experiments, the morphology, size, and uniformity of MnS inclusions can be optimized for the development of better free-cutting steels.
AB - Steels with good machinability are required for the ever-increasing demand for machining efficiency in industry. The manganese sulfide (MnS) inclusions in lead-free resulfurized free-cutting steels act as stress raisers, lowering the shear strength of steel such that the cutting resistance is reduced. Because the morphology of MnS critically determines the machinability of steels, the reactions involving the formation of MnS during solidification need to be carefully assessed, especially with regard to whether they are eutectic or monotectic reactions. In this paper, we established the relationships between alloying elements and solidified microstructures by utilizing both the CALPHAD-type thermodynamic modeling and high-temperature experiments at 1600 °C. The effects of sulfur content on the MnS microstructure were evaluated based on the solidification paths of the ideal iron-manganese-sulfur ternary system as well as the realistic iron-manganese-sulfur-silicon-carbon quinary system. Moreover, we systematically evaluated the effects of various alloying elements, namely hydrogen, boron, carbon, nitrogen, oxygen, aluminum, silicon, phosphor, argon, vanadium, chromium, cobalt, nickel, copper, arsenic, zirconium, niobium, molybdenum, tin, tantalum, tungsten, on the microstructure of MnS. Among those, oxygen is identified as a super-strong monotectic-stabilizer, and the addition of oxygen can drastically enhance the monotectic-type MnS, which is desirable for free-cutting steels. The thermodynamic predictions agree closely with experiments. With the combined efforts of thermodynamic calculations and high-temperature experiments, the morphology, size, and uniformity of MnS inclusions can be optimized for the development of better free-cutting steels.
UR - http://www.scopus.com/inward/record.url?scp=85057822858&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85057822858&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2018.11.290
DO - 10.1016/j.jallcom.2018.11.290
M3 - Article
AN - SCOPUS:85057822858
VL - 779
SP - 844
EP - 855
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
ER -