18CrNiMo7-6鋼齒輪軸開裂失效分析

18CrNiMo7-6鋼齒輪軸開裂失效分析Failure Analysis on Cracking of the 18CrNiMo7-6 Steel Gear Shaft

某18CrNiMo7-6鋼齒輪軸在機(jī)械加工結(jié)束后，在庫(kù)存期間發(fā)生了軸向開裂。利用宏觀分析、化學(xué)成分分析、滲碳層深度測(cè)定、掃描電鏡觀察、能譜分析等方法，對(duì)齒輪軸的開裂原因進(jìn)行了分析。結(jié)果表明：齒輪軸原材料冶煉過程不當(dāng)，混入了小顆粒狀氧化鋁類夾渣；在隨后的鍛打拉拔過程中小顆粒形成條帶狀，破壞了材料的連續(xù)性，形成應(yīng)力集中；在較大的殘余應(yīng)力作用下，齒輪軸發(fā)生了延遲性開裂。

The 18CrNiMo7-6 steel gear shaft cracked along the axial direction during storing after machining processing. The cracking reasons of the gear shaft were analyzed by methods of macroscopic analysis, chemical composition analysis, depth measurement of carburized layer, scanning electron microscopy observation, energy analysis and so on. The results show that:there were some particles of aluminium oxides mixed into the raw material of the gear shaft due to the improper smelting process; the particles were banded during forging and drawing process, which destroyed the continuity of the material and resulted in the stress concentration; under the action of large residual stress, delayed cracking occurred to the gear shaft.

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