Influence of heat treatment (routes) on the microstructure and mechanical properties of 300M ultra high strength steel

Shivraj Singh Kasana, Sandeep Sharma, O. P. Pandey

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The study covered investigation of heat treatment (routes) effect on heat treatment of 300M ultra high strength steel to achieve the desired microstructure and the corresponding mechanical properties. 300M steel was prepared and subjected to different homogenization and forging processing. Structure–property relationship was established for both conventional and heat treatment route as well as isothermal and modified route. Micrographs of 300M steels indicated that the isothermal heat treatment provided higher volume of retained austenite along with martensite and bainite. X-ray diffraction (XRD) revealed that the dislocation density of isothermally heat-treated 300M steels was higher than the conventional steel. Isothermally heat-treated 300M samples have shown improved elongation and impact strength with the marginal loss of yield strength and ultimate tensile strength. Yield strength (1605 MPa), ultimate tensile strength (1890 MPa), impact strength (28 J), and percentage elongation (22%) of the isothermally heat-treated samples were comparable to the specifications of the customer i.e., minimum yield strength 1480 MPa, ultimate tensile strength 1803 MPa, percentage elongation 7% and impact strength at − 40 °C of 20 J, respectively. The SEM analysis of tensile and impact fractured surfaces revealed the large number of dimples which indicate the good ductility and toughness in the isothermally heat-treated samples.

Original languageEnglish
Article number126
JournalArchives of Civil and Mechanical Engineering
Issue number3
StatePublished - Aug 2022
Externally publishedYes


  • 300M steel
  • Fracture analysis
  • Heat treatment
  • Mechanical properties
  • Microstructure


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