机加工表面强化技术的前世今生 [第一辑百年历程]

It is well established that in ancient times alreadymechanical treatments have been applied in many manufacturing processesconcerning metallic materials. Hammering evidently was the first mechanicalmethod to bring particular goods to final shape and strength.

在远古时代，机械加工处理就已经应用在金属材料领域。锤击是最早采用的机加工方法，它会给产品带来最终形状和强度。

 

In the historical development, individual craftmanshipand experiences influenced the application of mechanical hardening effects,whereby secrecy played an important role for the preservation of competitive advantages.

 

在历史发展的过程中，个人技艺和经验影响着机加工强化效果，因此保密在竞争优势的保留中起到了至关重要的作用。

 

However, not before the middle of the nineteenth century- running parallel to the development of the railroad technique - the firstsingle-minded applications of mechanical surface strengthening methods became known in the engineering science.

 

然而，在十九世纪中叶之前-平行于铁路技术的发展-最早的专用机加工表面强化方法的应用，在工程学中开始扬名。

 

Already in 1848, 'roll burnishing' was used forrailway axles and journals. Around 1880, cold-rolled shafts with improvedstrength and finish were successfully applied. In these formative years ofmodern technology it became quite obvious that in service, much more components and structures failed by cyclic than by static loading.

 

到了1848年，“滚磨光”被用于铁路车轴和轴颈。在1880年前后，提高强度和光洁度的冷轧轴得到了成功应用。在这个现代技术的成长期，很明显，更多的部件和结构在服役过程中在承受交变载荷而不是在静载荷作用下失效。

 

Consequently, since the classical work of A. W?hler, strong efforts were made to measure the resistance of materials to fatigue under controlled conditions and to understand the processes responsible for the fatigue behaviour. In the course of time, it was realized that failure by fatigue depends on a large number of parameters, and very often develops from particular surface areas of engineering parts.

 

因此，鉴于W?hler的经典之作，应用强化技术测试在受控条件下材料对疲劳的阻力以及理解材料的疲劳行为。随着时间的推移，人们认识到材料的疲劳失效取决于非常多的参量，并且材料的疲劳常常从工程构件的表面开始。 

 

Therefore, it seemed possible to improve the fatigue strength of fatigued parts by the application of suitable surface treatments,of which the mechanical surface strengthening processes represented animportant group.

 

因此，似乎可以通过恰当的表面处理来提高构件的疲劳强度，在这些表面处理方法中机加工表面强化工艺成为一个非常重要的群体。

 

Nowadays, we are very familiar with several mechanical surface treatments which alone or combined with other hardening processes can leadto significant improvements of the fatigue strength of materials under constantas well as random-like amplitude loading conditions.

今天，我们对一些表面机加工强化处理的方法已经非常熟悉了，它们或独自或与其它的强化方法相结合，能够显著提升材料在恒定载荷或无规则载荷条件下的疲劳强度

 

Also, the corrosion fatigue resistance of materials and the fretting corrosion behaviour of contacting surfaces can positively be influenced by mechanical means. The scientific fundamentals of these facts were developed in this century at the end of the 1920's and at the beginning of the1930's.

 

此外，材料的腐蚀疲劳阻力以及接触表面的摩擦腐蚀行为也可以得到显著改善。这些强化方法的科学基础在本世纪20年代末和30年代初得到了快速发展。

 

In this paper, the scientific and technological efforts will be outlined, which were made during the development of mechanical surface strengthening procedures to improve the fatigue strength of materials.

 

在这篇文章中，主要概括在发展表面机加工强化工艺提高材料疲劳强度过程中人们所做出的科技努力。

 

Excluding particular straining methods, e.g. coining or inhomogeneous plastic deforming, which can also be restricted to well-defined surface and subsurface areas, three different ways exist in which the fatigue strength can mechanically be effected: Firstly, by machining, secondly, by rollingand thirdly, by shot peening.

 

若不计特殊应变的方法，例如精压或不均匀塑性变形，这也可以限制为明确定义的表面和表面下的区域，存在三种不同的方式可以采用机加工方法影响材料的疲劳强度：首先，通过机械加工，其次，通过轧制，第三，通过喷丸硬化。

 

These processes are applicable to brittle as well as toductile materials. Furthermore, they are not restricted to materials with particular chemical composition or to distinct material states. Moreover, theycan be applied to smooth and notched surfaces.

 

这些方法也适用于脆性以及韧性材料。此外，它们并不限于具有特殊化学成分的材料或不同状态的材料。而且，它们可以用于光滑和带有缺口的表面。

 

In the following, the historical marks in the development of these three surface strengthening methods will be discussed in more detailup to the end of the 1950's. All data presented were carefully gathered and arewell documented.

 

在下文中，这三种表面强化方法的发展历史标识将更详细地讨论直到20世纪50年代末。文中对所有的数据进行了仔细收集并且有据可查。

 

However, the authors are not quite sure whether or not they overlooked some important documents. In the final chapter of the paper, it will be commented on some newer contributions to mechanical surface strengthening.

 

然而，作者也不清楚他们是否忽略了一些重要文件。在这篇论文的最后一章，对一些表面机加工强化的新贡献将进行评论。

 

Thereby, from the large amount of excellent work achieved by many scientists in the last three decades, for reasons of space only a few examples can be selected, of course individually.

因此，来源于过去三十年中许多科学家的大量优秀作品，限于篇幅的原因仅选出了部分例子，当然很个别。

 

This has been done with full respect to the entirety of investigations which determine the scientific and technological progress reached in this important field.

在充分尊重全部调研结果的基础上，这项工作已经完成，它们决定着这一重要领域所取得的科技进步。

2. Surface Strengthening byMachining，通过机加工表面强化

 

Most engineering parts are machined by processes like grinding, milling, turning, planing, honing and polishing.

 

大部分工程构件都会经过机加工处理，如磨、铣、车、搪磨和抛光。

 

In the surface areas of the machined parts, all these treatments produce work hardening effects, residual stress states and acharacteristic surface topography.

 

在机加工零件的表面区域，所有这些处理都会产生加工硬化效果，残余应力状态和特征表面形貌。

 

Tab. 1 gives a review of the first scientific investigations, which clearly pointed out the importance of the surface statefor the fatigue behaviour and the particular features of machined surfaces.

 

表1给出了第一个科学调查的总揽，它已明确指出了表面状态对材料疲劳行为的重要性，尤其是加工表面的特性。

Already in 1928, R. Mail?nder showed that differently polished surfaces led to differences in the fatigue behaviour of steels.

 

到了1928年，Mail?nder指出表面抛光不同会导致钢材疲劳行为出现差异。

 

As can be seen from Fig. 1, the fatigue strengths of specimens polished strongly were higher than of those polished slightly. At that time, it was also recognized that the surface roughness appreciably affectsthe fatigue strength.

 

从图1中可以看出，精细抛光样品的疲劳强度要比那些粗略抛光样品的疲劳强度高。当时，人们也认识到表面粗糙度明显地影响疲劳强度。

One of the first results, which documented that the effect of surface roughness on the fatigue strength in rotating bending increases with increasing tensile strength, is shown in Fig. 2. E. Houdremontand R. Mail?nder obtained these results from fatigue tests performed on polished and rough-turned specimens.

 

首批结果中的一个，文件记载了表面粗糙度的影响，扭转弯曲疲劳强度随拉伸强度提高而增大，如图2所示。Houdremont和Mail?nder从抛光样品和粗糙样品测试中获了这样的结果。

In each case, the rough-turned specimens held the lower quantities of fatigue strength. However, since machining also workhardened the surface area and produced residual stresses, it was not possible to evaluate clearly the roughness effect.

 

在每一种情况下，粗糙样品保持较低的疲劳强度。然而，因为机加工也使表面区域加工硬化，并产生残余应力，就很难清楚地评估粗糙度的影响效果。

  

In 1932 G. A. Hankins and M. L. Becker observed a marked reduction in the fatigue strength of spring steels due to decarburation effects. When the decarburized surface layers of the forged specimens was taken off by machining, the fatigue strength increased.

 

1932年，Hankins 和 Becker 观察到了弹簧脱碳以后其疲劳强度显著下降这种现象。当锻造试样表面脱碳层通过机加工除掉以后，其疲劳强度显著提高。

 

As can be seen from Fig. 3, in the case of very high-strength steels, the fatigue strength of the as-forged specimens was only about 20 % of that of the machined ones. This is one of the earliest documents showing in which dramatic way surface machining can influence the fatigue behaviour of materials with imperfect surface layers.

 

我们可以从图3中看到，在超高强度钢的条件下，锻造试样的疲劳强度只有机加工试样的20%。这是记录通过表面机加工影响不良表面可以显著改善疲劳行为最早的文献。

 

Not before 1936, it was shown by Ruttmann that due toturning, grinding and polishing, surface residual stress states occur, which penetrate to a certain depth into the machined material.

 

1936年以后，Ruttmann指出由于车削、磨削、抛光、表面产生残余应力状态，这种状态会穿透一定深度的被加工材料。

 

After polishing, compressive residual stresses up to 600N/mm2 were determined in high-strength steels. The first thorough investigation of the quantitative consequences of the surface roughness on the fatigue strength was performed by E. Siebel and M. Gaier.

抛光以后，在高强钢中压缩残余应力可以达到600MPa。Siebel和Gaier第一次进行了表面粗糙度对材料疲劳强度定量影响的全面研究。

 

For several steels and non-ferrous alloys, the surface roughnesses after performing various machining methods were measured and characterizedby the maximum depth of surface grooves R. Different correlations were found between the fatigue strength and R for differently heat-treated steels.

对于几种钢和非铁合金，经过不同加工方法处理的表面粗糙度，通过表面凹槽最大深度R进行测量和表征。发现了疲劳强度和R在不同热处理钢中的不同相关性。

However, no change in the fatigue strength was observed, provided that R was smaller than a critical value R0. Fig. 4 shows a typical result of this work. The so-called surface fatigue factor is drawn versus the logarithm of Rt. The results arevalid for push-pull and rotating bending tests.