Mechanical behavior of CrMo steel with tempered martensite and ferrite–bainite–martensite microstructure

“…3,4) The bainite structure has the excellent mechanical properties 3,5,6) and it can reduce the brittleness effect of the thin plate specimen (improve the strength and ductility) by controlling the different phases of matrix (the retained austenite content). According to the reference, 7) the characteristics of austempering SCM435 still not have been studied and the salt meet the environmental demands.…”

Section: Introductionmentioning

confidence: 99%

Microstructures and Mechanical Properties of Austempering Cr–Mo (SCM 435) Alloy Steel

et al. 2013

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SCM435 is a CrMo alloy steel and it is usually used to make the matrix of tempered-martensite by oil bath method, but it has some problems about reliability in the thin plate specimens. This research used the austempering heat treatment on the SCM435 thin plate specimen with a type of double loop and obtained the CrMo bainite structure, and then we could further investigate the mechanical properties of SCM435 bainite materials. Experimental data showed that the stability of the mechanical properties of the specimen with austempering temperature 830°C for 25 min was better than that of 15 min. The size of the austenite grains affected the strength of thin plate bainite specimen. After austempering at 830°C for 25 min and salt bath at 290°C, the stability of the ultimate tensile strength (UTS) was better than that of the salt bath specimens at 310 and 330°C. The average hardness of all the specimens was more than HRA70. The specimen with austempering at 830°C for 25 min and salt bath at 290°C for 30 min had bigger grain size of the austenite and retained £ phase of 11.4 vol%. It also had higher hardness and strength. So, the austempering SCM435 alloy was improved for tensile strength comparing with traditional oil tempered-martensite process.

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“…However, inferior mechanical properties have also been reported for these steel compared with those having conventional microstructures 8 . Salami et al 9,10 reported that the mechanical properties of tempered martensite are more favorable than those of ferrite -bainite -martensite microstructure in 42CrMo4 steel. They demonstrated that the high density of interphase boundary in ferrite -bainite -martensite microstructure was the main reason for the inferior mechanical properties of such a mixed microstructure.…”

Section: Introductionmentioning

confidence: 99%

Effect of Austenitizing Temperature on Mechanical Properties of the Mixed Bainite - Martensite Microstructure in CrMoV Steel

2017

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The effect of austenitizing temperature on mechanical properties of the mixed bainite -martensite microstructure in CrMoV steel was studied in the present work. The result showed that at low austenitizing temperature (910°C -1000°C), the mixed microstructures containing 12-28% volume fraction of lower bainite showed higher yield and tensile strength than fully martensitic microstructure. The partitioning of the prior austenite grain by lower bainite was found to cause a refinement of the martensite packet size. In addition the strength of the lower bainite in the mixed microstructure is enhanced by plastic constraint induced by the surrounding stronger martensite. By increasing the austenitizing temperature from 1000°C to 1200°C (40min), the YS, UTS, %EL, %RA and CVN impact energy decreased for all samples. This is attributed mainly to the increase in austenite grain size and width of bainite sheaves.

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Mechanical behavior of CrMo steel with tempered martensite and ferrite–bainite–martensite microstructure

Cited by 45 publications

References 17 publications

Microstructural evolution and mechanical properties of low-carbon steel treated by a two-step quenching and partitioning process

Microstructural evolution and mechanical properties of low-carbon steel treated by a two-step quenching and partitioning process

Microstructures and Mechanical Properties of Austempering Cr–Mo (SCM 435) Alloy Steel

Effect of Austenitizing Temperature on Mechanical Properties of the Mixed Bainite - Martensite Microstructure in CrMoV Steel

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Mechanical behavior of CrMo steel with tempered martensite and ferrite–bainite–martensite microstructure

Cited by 45 publications

References 17 publications

Microstructural evolution and mechanical properties of low-carbon steel treated by a two-step quenching and partitioning process

Microstructural evolution and mechanical properties of low-carbon steel treated by a two-step quenching and partitioning process

Microstructures and Mechanical Properties of Austempering Cr&ndash;Mo (SCM 435) Alloy Steel

Effect of Austenitizing Temperature on Mechanical Properties of the Mixed Bainite - Martensite Microstructure in CrMoV Steel

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Microstructures and Mechanical Properties of Austempering Cr–Mo (SCM 435) Alloy Steel