Statistical model of cleavage fracture in granular bainite in simulated weld heat affected zone

Effects of weld heat input on microstructures of coarse grain heat-affected zone (CGHAZ) were taken into account for bearing-Nb HF steel plate. For weld heat input from 12 to 20KJ/cm, grain boundary ferrite, degenerate pearlite and acicular ferrite are produced for steel plate with the Si/Mn ratio of 0.26. For higher input, bainite phase is found at the center of specimens. However, for the steel with the Si/Mn ratio of 6.2, granular bainite is dominant at weld heat input from 12 to 20KJ/cm. For further improving the weld heat input to 24KJ/cm, bainite nucleation at prior austenite grain boundaries is suppressed in the considered steel. Nb addition has obvious influences on microstructure.

Download Full-text

Investigation of the influence of the parameters of the laser welding technological process on the chemical composition, structural-phase state and physicochemical properties of the material of the weld, heat-affected zone, pipe body and product

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/939/1/012068 ◽

2020 ◽

Vol 939 ◽

pp. 012068

Author(s):

V V Savin ◽

L A Savina ◽

V A Chaika ◽

A S Martyushev ◽

S Z Lonchacov

Keyword(s):

Chemical Composition ◽

Laser Welding ◽

Physicochemical Properties ◽

Technological Process ◽

Heat Affected Zone ◽

Phase State ◽

Structural Phase ◽

Structural Phase State ◽

Weld Heat

Download Full-text

Continuous Cooling Transformation Diagram, Microstructures, and Properties of the Simulated Coarse-Grain Heat-Affected Zone in a Low-Carbon Bainite E550 Steel

Metals ◽

10.3390/met9090939 ◽

2019 ◽

Vol 9 (9) ◽

pp. 939 ◽

Cited By ~ 1

Author(s):

Yun Zong ◽

Chun-Ming Liu

Keyword(s):

Impact Toughness ◽

Cooling Rate ◽

Vickers Hardness ◽

Heat Affected Zone ◽

Granular Bainite ◽

Coarse Grain ◽

Low Carbon ◽

Transformation Diagram ◽

Lath Bainite ◽

Continuous Cooling Transformation Diagram

In order to provide important guidance for controlling and obtaining the optimal microstructures and mechanical properties of a welded joint, the continuous cooling transformation diagram of a new low-carbon Nb-microalloyed bainite E550 steel in a simulated coarse-grain heat-affected zone (CGHAZ) has been constructed by thermal dilatation method in this paper. The welding thermal simulation experiments were conducted on a Gleeble-3800 thermo-mechanical simulator. The corresponding microstructure was observed by a LEICA DM2700M. The Vickers hardness (HV) and the impact toughness at −40 °C were measured according to the ASTM E384 standard and the ASTM E2298 standard, respectively. The experimental results may indicate that the intermediate temperature phase transformation of the whole bainite can occur in a wide range of cooling rates of 2–20 °C/s. In the scope of cooling rates 2–20 °C/s, the microstructure of the heat-affected zone (HAZ) mainly consists of lath bainite and granular bainite. Moreover, the proportion of lath bainite increased and granular bainite decreased as the cooling rate increasing. There is a spot of lath martensite in the microstructure of HAZ when the cooling rate is above 20 °C/s. The Vickers hardness increases gradually with the increasing of the cooling rate, and the maximum hardness is 323 HV10. When the cooling time from 800 °C to 500 °C (t8/5) is 5–15 s, it presents excellent −40 °C impact toughness (273–286 J) of the CGHAZ beyond the base material (163 J).

Download Full-text

Properties of a thick-section narrow-gap gas tungsten arc weld of cast Haynes 282

Welding in the World ◽

10.1007/s40194-021-01077-4 ◽

2021 ◽

Author(s):

Michael Santella ◽

X. Frank Chen ◽

Philip Maziasz ◽

Jason Rausch ◽

Jonathan Salkin

Keyword(s):

Base Metal ◽

Heat Affected Zone ◽

Reference Data ◽

Filler Metal ◽

Stress Rupture ◽

Narrow Gap ◽

Weld Deposit ◽

Gas Tungsten Arc ◽

Gas Tungsten ◽

Weld Heat

AbstractA 50.8-mm-deep gas tungsten arc weld was made with matching filler metal in cast Haynes 282 alloy. The narrow-gap joint was filled with 104 weld beads. Visual and dye-penetrant inspection of cross-weld specimens indicated that the cast base metal contained numerous casting defects. No visible indications of physical defects were found in the weld deposit. The weld heat-affected zone was characterized by microcracking and localized recrystallization. The cause of the cracking could not be determined. Hardness testing showed that a softened region in the as-welded heat-affected zone was nearly eliminated by post-weld heat treatment. Tensile testing up to 816 °C showed that cross-weld specimen strengths ranged from 57 to 79% of the cast base metal tensile strength. The stress-rupture strengths of cross-weld specimens are within 20% of base metal reference data. Failures of both tensile and stress-rupture specimens occurred in the base metal.

Download Full-text