Study of welding characteristics of 0.3C–CrMoV(ESR) ultrahigh strength steel

Suresh, M.; Sinha, P. P.; Sarma, D. S.; Ballal, N. B.; Rao, P. Krishna

doi:10.1007/s10853-006-1115-3

Cited by 17 publications

(7 citation statements)

References 4 publications

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“…In welding, it is therefore essential to have steel with a low carbon equivalent (CE) which is an important indicator of the hardenability of HAZ. Alloys containing carbon C0.4 wt.% show a tendency to form martensite on welding and therefore are considered difficult to weld [7]. It is therefore necessary to limit the carbon content below 0.4% for heavy structural steels; if it is greater than this, controlled cooling of the weld is necessary to avoid risks of embrittlement.…”

Section: Discussionmentioning

confidence: 99%

Failure Analysis of HAZ Cracking in Low C–CrMoV Steel Weldment

Naz

Tariq

Baloch

2009

J Fail. Anal. and Preven.

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This case study describes the failure analysis of steel nozzle in which cracking was observed after a circumferential welding process. The nozzle assembly was made from low C-CrMoV alloy steel that was subsequently single pass butt welded using gas tungsten arc welding. No cracks were found in visual inspection of the welds; however, X-ray radiography showed small discontinuous cracks on the surface in the area adjacent to weld bead, i.e. heat affected zone. The welding of nozzle parts made of same material was a routine process and this type of cracking did not occur in the past. Therefore, it became essential to determine the root cause of the failure. A detailed investigation including visual examination, nondestructive testing, optical microscopy, microhardness measurements and residual stress measurements were carried out to find out the primary cause of failure and to identify actions required to avoid its reoccurrence in future. Results of the investigation revealed that the principal cause of failure was the presence of coarse untempered martensite in the heat affected zone due to localized heating. The localized heating was caused by high welding heat input or low welding speed and resulted in the high transformation stresses. These transformation stresses combined with the thermal stresses and the constraint conditions to cause intergranular brittle fracture.

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Section: Discussionmentioning

confidence: 99%

Failure Analysis of HAZ Cracking in Low C–CrMoV Steel Weldment

Naz

Tariq

Baloch

2009

J Fail. Anal. and Preven.

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“…For arc welded UHSS with similar strength and thickness, the size of the soft zone in the HAZ is about 6 to 8 mm (Refs. 14,16,17). As given in Fig.…”

Section: Welding Researchmentioning

confidence: 99%

“…However, the use of undermatching consumables makes the weld metal become the weak zone of the joints (Refs. 13,14). On the basis of related review (Refs.…”

Section: Introductionmentioning

confidence: 99%

Fiber Laser Welding of 1700-MPa, Ultrahigh-Strength Steel

2018

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This paper investigated the appearance, microstructure, and mechanical properties of laser welded joints for 1700-MPa, ultrahigh-strength steel (UHSS) with 6 mm thickness. The results indicate welding speed was the dominant factor that affected appearance quality. A sound weld without underfill can be obtained when the speed was limited to approximately 2-3 m/min. Two softening mechanisms exist in the heat-affected zone (HAZ). In the intercritical heataffected zone (ICHAZ), ferrite appears and the hardness drops sharply. For the subcritical heat-affected zone (SCHAZ), the microstructure was tempered martensite with precipitation of carbides and the high temperature temper results in the minimum hardness. With a martensitic structure in the weld metal and a narrow softening zone in the HAZ, more than a 94% joint efficiency was achieved in tensile testing. Only about a 40-deg maximum bending angle was obtained during a bend test, as plastic deformation mainly concentrates in the softening zone due to nonuniform hardness distribution. The study also found that the existence of porosities in the joints had significant affects on the ductility, toughness, and fracture mechanism, but little affect on the joint strength. For the joints without porosities, the fractures from tensile and bend tests both initiated at the zone with the minimum hardness and propagated along the 45-deg direction. But when porosities existed in the joints, fractures occurred completely in the weld metal, which resulted in a smaller elongation and bending angle as well as impact energy. However, the tensile strength was similar to an average value.

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“…Suresh et al [16] investigated the welding characteristics of 0.3CrMoV(ESR) ultrahigh strength steel under both hardened and annealed condition. It is found that this steel can produce high quality welds with improved toughness and tensile properties.…”

Section: Introductionmentioning

confidence: 99%