Improved toughness properties in the heat-affected zone of welded joints made from fine-grained structural steels

1985 ◽  
Vol 56 (12) ◽  
pp. 645-650 ◽  
Author(s):  
Heinrich Baumgardt ◽  
Christian Straßburger
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Structural Steels ◽  
Fine Grained

Effect of Cooling Condition on Microstructure and Mechanical Properties in Large Line Energy Welded Joints of Ultra-Fine Grained Steel

2011 ◽  
Vol 189-193 ◽  
pp. 3345-3350 ◽  
Author(s):  
Hong Yun Zhao ◽  
Li Zhou ◽  
Bo Chen ◽  
Guo Dong Wang
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Cooling Condition ◽  
Water Cooling ◽  
Line Energy ◽  
Fine Grained ◽  
Heavy Plate ◽  
Microstructure And Mechanical Properties

The medium and heavy plate of 800 MPa grade ultra-fine grained steel was welded by CO2 gas shielded welding using large line energy. The effect of cooling condition on microstructure and mechanical properties of welded joints was investigated. The results showed that the cases about significant grain size increasing and strength decreasing do exist in the heat affected zone of large line energy welded joints of 800 MPa grade ultra-fine grained steel. Grain growth and softening in the heat affected zone could be suppressed effectively by water cooling in the course of welding. The mechanical properties of welded joints could be significantly increased by water cooling, and the process of CO2 gas shielded welding under water cooling is practical for joining ultra-fine grained steel using large line energy.

scholarly journals The influence of manual metal arc multiple repair welding of long operated waterwall on the structure and hardness of the heat affected zone of welded joints

2017 ◽  
Vol 62 (1) ◽  
pp. 327-333 ◽  
Author(s):  
J. Pikuła ◽  
M. Łomozik ◽  
T. Pfeifer
Keyword(s):  
Heat Affected Zone ◽  
Welded Joints ◽  
Arc Welding ◽  
Power Plants ◽  
Welded Joint ◽  
Weld Bead ◽  
Boiler Steel ◽  
Metallographic Examination ◽  
Metal Arc Welding ◽  
High Degree

Abstract Welded installations failures of power plants, which are often result from a high degree of wear, requires suitable repairs. In the case of cracks formed in the weld bead of waterwall, weld bead is removed and new welded joint is prepared. However, it is associated with consecutive thermal cycles, which affect properties of heat affected zone of welded joint. This study presents the influence of multiple manual metal arc welding associated with repair activities of long operated waterwall of boiler steel on properties of repair welded joints. The work contains the results of macro and microscopic metallographic examination as well as the results of hardness measurements.

Diagnostics of threshold characteristics of welded joints in structural steels

1992 ◽  
Vol 6 (10) ◽  
pp. 815-817
Author(s):  
G V Matokhin ◽  
O I Steklov ◽  
A V Gridasov ◽  
I V Baranets
Keyword(s):  
Welded Joints ◽  
Structural Steels

Minimization of Heat-Affected Zone Size in Welded Ultra-Fine Grained Steel under Cooling by Liquid Nitrogen during Laser Welding

2007 ◽  
Vol 539-543 ◽  
pp. 4063-4068 ◽  
Author(s):  
Hideki Hamatani ◽  
Yasunobu Miyazaki ◽  
Tadayuki Otani ◽  
Shigeru Ohkita
Keyword(s):  
Laser Welding ◽  
Liquid Nitrogen ◽  
Heat Affected Zone ◽  
Laser System ◽  
Heat Removal ◽  
Plate Temperature ◽  
Fine Grained ◽  
Laser Beam Irradiation ◽  
Average Grain Size ◽  
Plume Temperature

Ultra-fine grained steel (UFGS) with an average grain size of less than 1μm has been developed and is expected to demonstrate superior properties. However, its welded heat-affected zone, HAZ, substantially affecting the strength of a welded joint, will be easily softened after welding. Therefore, minimization of UFGS’s HAZ size during laser welding was carried out using the cooling conductor liquid nitrogen. It was found that a shielding gas with adequate flow rate for the liquid nitrogen depth was used to displace nitrogen on the area of laser beam irradiation to stabilize the weld bead. Also, because YAG laser system was mainly used because it has a lower laser induced plasma or plume temperature, which results in a decreased occurrence of pit and blowhole. HAZ size minimization strongly depends on the initial plate temperature. Reduced initial plate temperature shrinks the specific heated temperature range in which softening occurs. However, due possibly to decreasing thermal conductivity under room temperature, which prevents heat removal, the benefit of reducing the initial plate temperature is limited. The optimal initial temperature to minimize the HAZ size, in the present work, was found to be 123K.

Sign in / Sign up

Export Citation Format

Share Document