熱處理是提高和保證機(jī)械產(chǎn)品質(zhì)量和可靠性，提高制造業(yè)競爭力的重要基礎(chǔ)之一。 其行業(yè)水平的高低對制造業(yè)的發(fā)展起著舉足輕重的作用。 目前，除少數(shù)廠家外，我國熱處理行業(yè)整體水平遠(yuǎn)不能適應(yīng)加入WTO后熱處理行業(yè)面臨的更加激烈的市場競爭環(huán)境。 其中，我國的熱處理檢測設(shè)備更為落后。 嚴(yán)重的限制和障礙阻礙了工藝技術(shù)的發(fā)展，造成產(chǎn)品質(zhì)量的不穩(wěn)定，更重要的是不能有效防止產(chǎn)品不必要的質(zhì)量事故。 下面我將舉例說明機(jī)械零件和工具熱處理后最常用的硬度測試。

  硬度是衡量金屬材料軟硬程度的指標(biāo)。 硬度值實際上并不是物理量的單位。 它是代表材料的彈性、塑性、變形、強(qiáng)化率、強(qiáng)度和韌性等一系列不同物理量組合的綜合性能。 指標(biāo)，一般可以認(rèn)為硬度是指金屬表面在小體積內(nèi)抵抗變形和開裂的能力。 使用便攜式里氏硬度計進(jìn)行硬度檢測的實用價值在于不需要破壞工件，可以批量檢測零件。 它已成為產(chǎn)品質(zhì)量檢驗、制定合理工藝和分析產(chǎn)品質(zhì)量的重要實驗方法之一。

  結(jié)構(gòu)件及模具檢測實際使用

  使用里氏硬度計測試硬度來分析驗證大型齒輪軸和齒圈的預(yù)處理工藝和滲碳淬火工藝

  1. 預(yù)處理過程后測試

  該工序操作后的質(zhì)量直接影響滲碳工序后小齒輪和內(nèi)齒圈滲碳層硬度分布的均勻性，以及輪齒的變形情況。 更重要的是核心（未穿透層）的強(qiáng)度。 用里氏硬度計測試小齒輪的齒部和柄部、外圓內(nèi)徑和內(nèi)齒圈端面時，如果發(fā)現(xiàn)同一區(qū)域的最高和最低硬度 測試相差很大，要復(fù)查儀器爐溫和爐子安裝方法。 在工藝?yán)鋮s方式正常的前提下，根據(jù)硬度值的差異和分布，可以推斷出工件組織存在偏析或帶狀組織。 金相圖中顯示的帶偏析是因為黑色珠光體帶的測試點(diǎn)硬度較高，而白色鐵素體帶的硬度較低。 這種結(jié)構(gòu)缺陷在隨后的滲碳淬火操作中不能消除，而是保留下來。 大型齒輪軸和內(nèi)齒輪一旦出現(xiàn)這樣的結(jié)構(gòu)缺陷，不僅會在安裝和使用過程中造成使用壽命短的問題，而且往往會引發(fā)重大設(shè)備事故。 當(dāng)我們通過硬度法測試可以推斷出鍛件存在這種帶偏析時，可以通過固溶處理工藝操作或其他工藝消除缺陷，立即消除帶偏析，從而防止設(shè)備事故的發(fā)生，減少損失 .

  2、滲碳后測試

  在小齒輪和齒圈的最終熱處理過程中，檢驗人員通常只測試樣品的HRC硬度，然后切割樣品進(jìn)行金相分析：馬氏體水平、碳化物水平、形態(tài)分布、殘余奧氏體量、 采用顯微硬度計測試從表層滲入層到深層深度以上的HV550硬度作為最終檢驗。 但從齒輪軸早期失效和齒嚴(yán)重磨損的事故分析中發(fā)現(xiàn)，實物硬度低于試樣硬度，尤其是深滲碳。 樣品不是從同一個塊上切下來的，也不是在同一個爐子中預(yù)處理的。 這樣，實物與滲入前的樣品的原始結(jié)構(gòu)不同，滲入后的結(jié)構(gòu)和硬度也有一定的差異。 更重要的是，在整個滲碳過程操作中，由于工件的放置位置和滲碳表面積的巨大差異（化學(xué)熱處理吸收相界面反應(yīng)和過程中的主要因素）有非常重要的影響。 浸滲介質(zhì)各組分的濃度和工件的表面狀態(tài)、表面形狀、表面積和表面能對化學(xué)熱處理工藝有極其重要的影響。） 里氏硬度計 與洛氏硬度計和顯微硬度計對試樣測得的硬度進(jìn)行比較，結(jié)合試樣滲層的金相組織分析，可以快速準(zhǔn)確地找出質(zhì)量問題的原因。 結(jié)合必要的工藝調(diào)整，可以在工件組裝前消除事故隱患。

  使用里氏硬度計測試硬度來分析驗證中大型復(fù)雜結(jié)構(gòu)的模具技術(shù)

這是一種由馬氏體不銹鋼制成的飼料模具，主要用于生產(chǎn)飼料。 模具上有10000-27000個孔，每小時10噸混合飼料粉末從模具孔區(qū)擠出成顆粒。 因此，環(huán)模質(zhì)量和使用壽命的關(guān)鍵控制點(diǎn)是環(huán)模上?？讌^(qū)的硬度和滲層。

  由于模具尺寸較大，模具孔分布在外圓，所以測試點(diǎn)為曲面，孔間距一般為3～4mm。 在此條件下，發(fā)揮了里氏硬度計的多種適用性和緊湊性。 方便的功能可以準(zhǔn)確測試?？椎膶嶋H硬度。 根據(jù)測得的硬度和試塊的金相分析，可以更合理地修改和制定工藝，充分發(fā)揮材料的潛力，提高使用壽命。 例如，環(huán)模每小時可生產(chǎn)10噸飼料，使用壽命延長10小時，可生產(chǎn)100噸飼料，將為企業(yè)帶來巨大的經(jīng)濟(jì)效益。

  里氏硬度計在工模具失效分析中的作用

  5CrMnMo制成的大型熱鍛模具在使用過程中經(jīng)常因型腔過早磨損和塌陷而失效。

  當(dāng)用里氏硬度計測試磨損區(qū)的硬度時，發(fā)現(xiàn)磨削的硬度值低于使用前測試的硬度（38-42HRC）在32-34HRC范圍內(nèi)。 這意味著在第二階段加熱紅熱毛坯（>10000C）的型腔時（型腔內(nèi)的毛坯加熱大致可分為四個階段），當(dāng)熱量約為80%～85%時，由于 腔壁厚散熱慢，有些點(diǎn)溫度高達(dá)6500C以上。 當(dāng)模具型腔的溫度通過傳導(dǎo)加熱后超過模具的回火溫度時，模具在工作過程中處于連續(xù)回火過程階段，結(jié)構(gòu)和性能的變化會不斷發(fā)生，導(dǎo)致減少 磨損區(qū)的硬度值與發(fā)熱的發(fā)生有關(guān)。 磨損，說明5CrMnMo熱作模具鋼不適用于大型模具。 在使用600-6500C溫度范圍內(nèi)的熱作模具鋼時，如3Cr2W8V和3Cr3Mo3VNb，具有熱穩(wěn)定性、熱強(qiáng)度和屈服強(qiáng)度的熱作模具鋼比5CrMnMo更適合。

  我國工業(yè)化進(jìn)程遠(yuǎn)未完成，亟待縮小與國際先進(jìn)制造業(yè)水平的差距。 作為一個企業(yè)，要從戰(zhàn)略的高度認(rèn)識熱處理行業(yè)，不僅是設(shè)備、技術(shù)，尤其是檢測設(shè)備。 吸收國內(nèi)外新技術(shù)，還取決于熱處理企業(yè)的實際生產(chǎn)和應(yīng)用。 這是一個非常明智的舉動，因為加入世貿(mào)組織后，按照世貿(mào)組織規(guī)則有一個五年的過渡期。 對于我國的制造業(yè)來說，這是一個非常關(guān)鍵的時期。 工業(yè)企業(yè)將基本處于與國外大型企業(yè)同等的競爭地位，在這個過渡時期，我們?nèi)匀豢梢猿浞譁?zhǔn)備提升競爭力，所以這是對企業(yè)非常迫切的要求。

英斯特力儀器是一家集研發(fā)、生產(chǎn)及銷售于一體的 影像測量儀，拉力試驗機(jī), 硬度計 ,探傷儀, 粗糙度儀, 測厚儀, 金相設(shè)備廠家, 致力于為客戶提供更好的檢測儀器。

Heat treatment is one of the important bases to improve and guarantee the quality and reliability of mechanical products and enhance the competitiveness of manufacturing industry. The level of its industry plays a decisive role in the development of manufacturing industry. At present, except for a few manufacturers, the overall level of China's heat treatment industry is far from adapting to the more intense market competition environment faced by the heat treatment industry after China's entry into WTO. Among them, the heat treatment testing equipment in China is more backward. Serious limitations and obstacles hinder the development of process technology, resulting in the instability of product quality, more importantly, can not effectively prevent unnecessary product quality accidents. Below I will illustrate the hardness tests most commonly used after heat treatment of mechanical parts and tools.

Hardness is a measure of how hard or soft a metal material is. Hardness values are not actually units of physical quantities. It represents the comprehensive properties of a series of different physical quantities such as elasticity, plasticity, deformation, strengthening rate, strength and toughness of materials. Hardness is generally considered to be the ability of a metal surface to resist deformation and cracking in a small volume. The practical value of using portable Richter hardness tester for hardness testing is that parts can be tested in batches without destroying the workpiece. It has become one of the important experimental methods for product quality inspection, formulation of reasonable process and analysis of product quality.

The actual use of structural parts and molds testing

The pretreatment and carburizing and quenching processes of large gear shaft and gear ring were analyzed and verified by testing hardness with Richter hardness tester

1. Test after the pretreatment process

The quality of the carburizing process directly affects the uniformity of hardness distribution of the carburizing layer of pinion and inner ring and the deformation of gear teeth. More important is the strength of the core (the unpenetrated layer). When testing pinion teeth and handle, outer circle inner diameter and inner ring end face with The Richter hardness tester, if it is found that the maximum and minimum hardness tests in the same area are very different, check the instrument temperature and furnace installation method. Under the premise of normal process cooling mode, it can be inferred that there is segregation or banded structure in the workpiece structure according to the difference and distribution of hardness values. The band segregation shown in the metallographic is due to the higher hardness of the test point of the black pearlite band and the lower hardness of the white ferritic band. This structural defect is not eliminated but retained during subsequent carburizing and quenching operations. Such structural defects of large gear shafts and internal gears will not only cause short service life in the process of installation and use, but also often lead to serious equipment accidents. When we can infer the existence of this kind of segregation by hardness test, the defects can be eliminated by solution treatment process operation or other processes, immediately eliminate the segregation, so as to prevent the occurrence of equipment accidents and reduce losses.

2. Test after carburizing

In the pinion and ring gear final heat treatment process, the inspectors are usually only test samples of HRC hardness, metallographic analysis and cutting samples: martensite, carbide level austenite content, form, and the microhardness meter test from infiltration of surface layer to deep depth above HV550 hardness as the final inspection. However, it is found from the analysis of early failure of gear shaft and severe tooth wear that the hardness of material object is lower than that of sample, especially deep carburizing. Samples are not cut from the same block, nor are they preprocessed in the same furnace. In this way, the original structure of the material object is different from that of the sample before infiltration, and the structure and hardness after infiltration also have certain differences. More importantly, in the entire carburizing process operation, due to the workpiece placement position and carburizing surface area of the huge difference (chemical heat treatment absorption phase interface reaction and the main factor in the process) has a very important influence. The concentration of each component of the infiltration medium and the surface state, surface shape, surface area and surface energy of the workpiece have very important effects on the chemical heat treatment process. By comparing the hardness of samples measured by Richter hardness tester with Rockwell hardness tester and microhardness tester, the reason of quality problems can be found out quickly and accurately by analyzing the metallographic structure of the permeable layer of samples. Combined with necessary process adjustment, accident potential can be eliminated before the workpiece assembly.

Use the Richter hardness tester to test hardness to analyze and verify the mold technology of medium and large complex structures

This is a feed mold made of martensitic stainless steel, mainly used for the production of feed. There are 10,000-27,000 holes in the mold, and 10 tons of mixed feed powder is extruded into granules from the hole area of the mold per hour. Therefore, the key control points for the quality and service life of the ring die are the hardness and infiltration layer in the hole area of the ring die.

Due to the large mold size, mold holes are distributed in the outer circle, so the test point is curved surface, hole spacing is generally 3 ~ 4mm. Under these conditions, various applicability and compactness of The Richter hardness tester are developed. Convenient function can accurately test the actual hardness of the die hole. According to the hardness measured and the metallographic analysis of the test block, the process can be modified and formulated more reasonably, so as to give full play to the potential of the material and improve the service life. For example, the ring mold can produce 10 tons of feed per hour, the service life of 10 hours, can produce 100 tons of feed, will bring huge economic benefits for the enterprise.

The function of Richter hardness tester in die failure analysis

Large hot forging dies made of 5CrMnMo often fail due to premature wear and collapse of the cavity during use.

When the hardness of the wear zone was tested with a Richter hardness tester, it was found that the hardness values of the grinding were lower than those of the pre-service test (38-42HRC) in the 32-34HRC range. This means heating red-hot blanks in the second stage (& GT; 10000C) of the cavity (the blank heating in the cavity can be roughly divided into four stages), when the heat is about 80% ~ 85%, due to the slow heat dissipation of the cavity wall thickness, some point temperature is as high as 6500C or more. When the temperature of the mold cavity exceeds the tempering temperature of the mold through conduction heating, the mold is in a continuous tempering process stage in the working process, and the changes of structure and performance will occur constantly, resulting in the hardness value of the wear zone is related to the occurrence of heating. Wear, indicating that 5CrMnMo hot work die steel is not suitable for large die. When using hot work die steels in the 600-6500C temperature range, such as 3Cr2W8V and 3Cr3Mo3VNb, hot work die steels with thermal stability, thermal strength and yield strength are more suitable than 5CrMnMo.

China's industrialization process is far from complete and it is urgent to narrow the gap with the international advanced manufacturing level. As an enterprise, we should understand the heat treatment industry from a strategic height, not only equipment, technology, especially testing equipment. The absorption of new technology at home and abroad depends on the actual production and application of heat treatment enterprises. This is a very wise move, because after joining the WTO, there is a five-year transition period according to WTO rules. This is a very critical period for our manufacturing industry. Industrial enterprises will basically be in the same competitive position as large foreign enterprises. In this transition period, we can still fully prepare to enhance competitiveness, so this is a very urgent requirement for enterprises.