Effect of Austenite Grain Size on the Morphology and Crystallography of Lath Martensite in Low Carbon Steels

Abstract

The crystallography, microstructure and mechanical property of as-quenched martensite of Fe-0.2C-Mn(-V) alloys of which the prior austenite grain sizes are 370-2 mm were studied. The prior austenite grain, whose size is larger than 28 mm, is divided by several packets. Those packets are subdivided by blocks containing sub-blocks, each of which corresponds to the Kurdjumov-Sachs variant. When the prior austenite grain size is about 2 mm, one packet tends to grow predominantly. Each packet is divided by blocks containing sub-blocks.

Subgrain lath martensite mechanics: A numerical–experimental analysis

“…The thickness of the laths is expected to be of the order of 100-200 nm. In general, the dimensions of crystallographic packets and blocks in lath martensite can vary considerably, depending on the prior austenite grain size (Morito et al, 2005) …”

Decrease in Hydrogen Embrittlement Susceptibility of 10B21 Screws by Bake Aging

“…Lath martensite only appears in low-carbon steel matrix, and grows in the orientation of the austenite grain [12]. After tempering for 30 min, the entire screw consisted of uniform tempered martensite with scattered recrystallized ferrite ( Figure 2b).…”

Optimizing Gear Performance by Alloy Modification of Carburizing Steels

“…It was shown on the example of 18CrNiMo7-6 that below an average martensite packet size of 20 µm, the impact toughness strongly increases [11]. Since the packet size strongly correlates with the prior austenite grain size [11,12], control and refinement of the latter one across the entire processing chain is an appropriate means of improving toughness. Figure 9.…”