【正文】 從提高零件抵抗疲勞破壞的角度考慮，該表面最終工序應選擇能在該表面產(chǎn)生殘余壓應力的加工方法。 如果表面層金屬產(chǎn)生了金相組織的變化，表層金屬比容的變化必然要受到與之相連的基體金屬的阻礙，因而就有殘余應力產(chǎn)生。 （三）表面層殘余應力 1. 產(chǎn)生殘余應力的原因 a. 切削時在加工表面金屬層內(nèi)有塑性變形發(fā)生，使表面金屬的比容加大 。在磨削淬火鋼時，可能產(chǎn)生以下三種燒傷： 如果磨削區(qū)的溫度未超過淬火鋼的相變溫度，但已超過馬氏體的轉(zhuǎn)變溫度，工件表層金屬的回火馬氏體組織將轉(zhuǎn)變成硬度較低的回火組織 (索氏體或托氏體 )，這種燒傷稱為回火燒傷。進給量增大，切削力也增大，表層金屬的塑性變形加劇，冷硬作用加強。 2. 影響冷作硬化的主要因素 切削刃鈍圓 半徑增大，對表層金屬的擠壓作用增強，塑性變形加劇，導致冷硬增強。 被冷作硬化的金屬處于高能位的不穩(wěn)定狀態(tài)，只有一有可能，金屬的不穩(wěn)定狀態(tài)就要向比較穩(wěn)定的狀態(tài)轉(zhuǎn)化，這種現(xiàn)象稱為弱化。 三、影響加工表面層物理機械性能的因素 在切削加工中，工件由于受到切削力和切削熱的作用，使表面層金屬的物理機械性能產(chǎn)生變化，最主要的變化是表面層金屬顯微硬度的變化、金相組織的變化和殘余應力的產(chǎn)生。工件材料韌性愈好，金屬的塑性變形愈大，加工表面就愈粗糙。 二、影響表面粗糙度的因素 （一）切削加工影響表面粗糙度的因素 1. 刀具幾何形狀的復映 刀具相對于工件作進給運動時，在加工表面留下了切削層殘留面積，其形狀時刀具 幾何形狀的復映。 表面層的殘余拉應力會產(chǎn)生應力腐蝕開裂，降低零件的耐磨性，而殘余壓應力則能防止應力腐蝕開裂。 表面冷硬一般伴有殘余應力的產(chǎn)生，可以防止裂紋產(chǎn)生并阻止已有裂紋的擴展，對提高疲勞強度有利。 1. 表面粗糙度對疲勞強度的影響 在交變載荷作用下，表面粗糙度的凹谷部位容易引起 應力集中，產(chǎn)生疲勞裂紋。因此，接觸面的粗糙度有一個最佳值，其值與零件的工作情況有關，工作載荷加大時，初期 磨損量增大，表面粗糙度最佳值也加大。 零件磨損一般可分為三個階段，初期磨損階段、正常磨損階段和劇烈磨損階段。Two is an improvement to cool off the condition, make produce the amount of subterranean heat as far as possible little stream into the work piece. (C)The surface layer remaining should dint 1. Produce remaining of should the reason of the dint a. Slice to pare have the mold to transform the occurrence in process the surface metals layer, make the metal ratio of surface permit the the mold transform only creation in the surface layer metals, but the ratio of the surface layer metals permits the aggrandizement, the physical volume inflation, the mile layer that want to be subjected to connect with each other with it inevitably metals of arrestment, so produced in the surface metals layer Remaining dint, but produce the remaining to pull in in the layer metals should dint. b. Slice to pare to process medium, slice and pare the area and there will be to slice to pare the hot creation in great quantities. c. The different gold anizes the density of have the dissimilarity mutually, also having the different ratio to the surface layer metals produced the variety that gold mutually anize, the variety that the surface layer metals pares to permit want to be subjected to by all means with its the bar of the base body metals for connect with each other, as a result there is Remaining dint creation. 2. The end work preface of main work surface of spare parts processes the choice of method The end work preface of main work surface of spare parts processes the method to choose to the pass importance, because the end work preface is should work remaining of surface leave should the dint will affect the usage function of the machine parts directly. Choose the main end work preface of surface of work of spare parts processes the method, must consider the concrete work condition and possible breakage forms of the surface of main work of that spare partses. At hand over to change to carry the lotus function under, superficially partial tiny view crack of machine parts, meeting because of pull should the function of the dint make living at first the crack extension, causing spare parts split spare parts resists from the exaltation tired breakage of angle consider, the end work preface of that surface shoulds choose and can produce the remaining to press in that surface should the dint process the method. 外文翻譯（譯文） 機械加工表面質(zhì)量 摘要： 機械零件的破壞，一般總是從表面層開始的。s change temperature, a surface layer of work metals returns to the fire MA3 ZHI TI339。附錄 1 外文翻譯（英文原文） The Surface Quantity While Machine Processes Abstract:The breakage of the machine spare parts, generally always from the surface layer beginning function of the product, particularly its credibility and durable, be decided by the quantity of the spare parts surface layer to a large that studies the machine to process the surface quantity be for control the machine process medium various craft fa