Influence of Cooling Rate on the Hot Cracking Formation of Nickel Rich Alloys.

Abstract

Hot cracking formation and its mechanism in invar alloys (Fe-36mass%Ni) during continuous casting was investigated. The invar alloy is very sensitive to hot cracking due to its low transition temperature of brittle to ductile fracture even though its solidification interval is narrow. At the cooling rate of 10°C/min the transition temperature of brittle to ductile fracture is about 113°C below the solidus temperature. An increased cooling rate in invar alloy increases transition temperature of brittle to ductile fracture. It is increased to about 43°C below the solidus temperature when the cooling rate is increased to 100°C/min. A mechanism of hot cracking formation in invar alloys has been proposed. Hot cracks in invar alloys with a fast cooling rate are formed between the primary dendrites due to the equiaxed solidification structure. However, at slow cooling rate, hot cracks are formed between the grain boundaries due to the columnar structure.

304 Paslanmaz çeliğin mikroyapı ve mekanik özellikleri üzerinde yüksek enerjili lazer kaynak parametrelerinin etkisi

“…The crack initiation and propagation are also easier in the coarse columnar zone. According to the shrinkagebrittleness theory, the contraction strains increase from coherent temperature to solid temperature during cooling [34]. In this critical temperature range, the remaining liquid phase cannot move freely due to the presence of the solid phase network.…”

Investigations on Decreased High Temperature Ductility of Different Continuously Cast Steel Grades

“…Variation of parameter sets [20,[24][25][26][27][28] in hot ductility testings thus provide important information on possible adjustments of the casting process to match the materials' properties. [2,10,11,58,60] www.advancedsciencenews.com Figure 2 shows the qualitative influence of various alloying elements. Ratios and products of alloying elements, that form a joint precipitated which affects the ductility are considered.…”

“…Schematic representation of RA curve for high temperature ductility, depending on: temperature, individual composition, formed precipitates, and phase transformations, representation based on data from literature. [2,10,11,58,60] www.advancedsciencenews.com sets [20,[24][25][26][27][28] in hot ductility testings thus provide important information on possible adjustments of the casting process to match the materials' properties.…”

“…Figure1. Schematic representation of RA curve for high temperature ductility, depending on: temperature, individual composition, formed precipitates, and phase transformations, representation based on data from literature [2,10,11,58,60]. …”

Mechanical Properties of Inconel 718 Nickel-Based Superalloy around Solidus Temperature

“…で加熱し，30 秒間等温保持を行った後，引張を開始している．引張速度は，固液共存温度域における引張試験に関する 従来の文献を参考に 30 mm/min とした28,29,31) ．試験片表面 の酸化を防ぐため，Ar ガス雰囲気にて加熱をしており，試 験片の表面はエメリー紙(# 800, # 1200)を用い長手方向に研…”