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The Study on Microstructure and Properties of Modified Layer of 40Cr Laser Transformation Hardening Surface Modification

Author: QiuLing
Tutor: LiGang
School: Liaoning Technical University
Course: Materials Processing Engineering
Keywords: Laser transformation hardening Fundamental mode Multimode Microhardness
CLC: TG174.44
Type: Master's thesis
Year: 2008
Downloads: 33
Quote: 0
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Abstract


In this thesis work chosen 40Cr steel as matrix , the fundamental mode beam laser transformation hardening surface modification and different process parameters on the microstructure and properties of the modified layer , simultaneously with the selection of the multimode beam conditions hereinafter the same material surface modification of materials process compared to the analysis of the characteristics of the microstructure and mechanical properties of the modified layer . Experimental results show that : the fundamental mode beam laser transformation hardening modified layer is divided into phase transformation hardened zone and the transition zone ; organization acicular martensite lath martensite and retained austenite phase transformation hardened zone ; transitional zone of mixed martensite and unmelted iron ferrite ; XRD analysis shows that the modified layer martensite strengthening phase . Sample after axial fundamental mode beam surface modification , the the sectional maximum hardness point appears in the subsurface ; With the improvement of the scanning speed of the surface hardness of the highest value and then decreased ; When the scanning speed is 42 mm · s - 1 , the surface hardness reached maxima 1097.9HK ; with the increase in the spot diameter the modification zone microhardness value decreased ; modified layer depth of the two beam patterns are increased with increasing energy density , and multi- mode beam depth of the modified layer compared to the fundamental mode beam modification layer should be deep; cross-flow the multimode beam surface modification after the abrasion resistance of the sample is superior to the sample after the axial fundamental mode beam surface modification ; sample after the laser transformation hardening can improve corrosion resistance .

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metal corrosion protection,metal surface treatment > Corrosion control and protection > Metal surface protection technology > Metal complex layer of protection
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