A new grade for Titanium

一種新級別的鈦

     Many ASTM International material specifications were written decadesago. While these specifications have evolved, the specified minimum propertieshave rarely been revisited since they were first established. In the interim,the industry has invested millions of dollars upgradingcapabilities to produce a6 better and more consistent product. In some cases, these advances may justify revising themechanical, chemical, or other requirements of corresponding ASTM specifications.

許多ASTM國際材料規范都是十多年前起草的。然而，盡管這些規范不斷被修訂，但自首次發(fā)布后，標準規定的性能指標下限卻很少修訂。在該規范運行期間，本行業(yè)已經(jīng)投資數百萬(wàn)美元升級能力，制造出質(zhì)量更穩定、性能更好的產(chǎn)品。在這種情況下，這些投資是ASTM標準的物理性能、化學(xué)成分或其他技術(shù)要求合理修訂所必須進(jìn)行的工作。

（在某些情況下，這些進(jìn)步是可以證明ASTM 標準下物理性能，化學(xué)成分或者其他技術(shù)要求的修訂是正確的。）

 Anexample of such an activity is the recent addition of the "H grades"to the ASTM titanium specifications by ASTM Committee BI0 on Reactive andRefractory Metals and Alloys.

舉例來(lái)說(shuō)，近期，ASTM BI0（活性和難熔金屬及合金委員會(huì )）在ASTM純鈦規范中增加了一種"H "級別。                          

This paper discusses: Thebackground leading to this particular change, How thetraditional role of producers in property development was replaced by a usergroup that saw an economic advantage in the change, The importance ofthe ASTM committee consensus process, and A summary of the expected benefits.

本文討論了：

1、引進(jìn)這種"H "級別純鈦的背景

    2、注重經(jīng)濟利益的應用群體取代了制造商在提高產(chǎn)品性能方面發(fā)揮的重要作用

    3、在提高產(chǎn)品性能方面，傳統生產(chǎn)商是如何被注重經(jīng)濟效益的用戶(hù)群體所取代的？

    4、通過(guò)ASTM 委員會(huì )多數成員表決的重要性

    5、本"H "級別純鈦的預期效益概述

 

BACKGROUND

The40 to 50-year-old data used to develop current ASTM titanium properties may nolonger represent modern material. Changes in production practice have resultedin more consistent material chemistry with reduced levels of residual elementswhose combined effect is not fully  understood. Producershave to control titanium ingot chemistry so accurately that their ability toachieve consistent results and variation in properties is vastly improved fromwhen the ASTM titanium specification property values were first established.

   背景

40-50年來(lái)積累的數據慣用于顯示當前的ASTM純鈦性能的變化趨勢，而不是有目的地為發(fā)展現有該牌號而收集。為使產(chǎn)品性能的實(shí)際變化較小，質(zhì)量一致性更高，就要求減少材料中殘余化學(xué)元素含量，因為這些殘余元素共同作用的效果是難以預測的。因此必須嚴格控制純鈦鑄錠的化學(xué)成分，以使鑄錠成分結果保持一致性，同時(shí)保證了自ASTM鈦金屬規范性能指標首次發(fā)布后，性能指標逐步有了較大提高。

 

過(guò)去用來(lái)發(fā)展ASTM標準下鈦材性能的40-50年的數據積累可能不在代表現代材料。生產(chǎn)過(guò)程中的改進(jìn)使材料的化學(xué)成分更加一致，減少了殘余化學(xué)成分含量（這些殘余化學(xué)成分共同作用下的效果還沒(méi)被完全掌控。）生產(chǎn)商不得不精確控制鈦錠的化學(xué)成分，使鑄錠成分和結果更加一致，同時(shí)，性能相比于ASTM標準下首次公布的鈦金屬性能參數，也有了很大的提高。

 

 

A 1998 review ofapproximately 250 Grade 2 titanium test reports found that all reportedultimate tensile strength, or UTS, values exceeded 60 ksi (410 MPa), well abovethe 50ksi (345 MPa) specification minimum. The results were presented to titaniumproducers with a proposal that if this were true in a substantially largersample, the industry might produce a competitive advantage for titanium bysimply changing the minimum specified UTS to reflect what was routinely beingachieved in practice.^1,2 Sincethe American Society of Mechanical Engineers' Code Design Allowable Stressesfor titanium are controlled by the minimum UTS, a significant savings inequipment cost could be realized if higher allowable stresses based on a higherminimum specified UTS could be utilized. Because the ASME code is used as thebasis for a wide range of industrial equipment, the effect of such a changewould be significant.

1998版修訂時(shí)，統計了約250份Gr2純鈦實(shí)驗報告，結果所有抗拉強度都大于410 Mpa，當然都比標準規定的最小指標345 Mpa高。提出的指標是建立在假定大量的試樣是充分的和真實(shí)的基礎上的。企業(yè)制造的產(chǎn)品若僅僅只是抗拉強度比通常標準規定的最小指標高，也會(huì )大大提高其競爭優(yōu)勢。由于美國機械工程協(xié)會(huì )設計時(shí),純鈦的許用強度UTS按最小值計算，因此利用比標準規定的最小強度UTS高的材料在制造設備方面可達到極大節省。因為ASME標準被廣泛使用于工業(yè)設備，這種變化意義將相當重大。

 

ROLE OF THEMATERIALS TECHNOLOGY INSTITUTE

材料技術(shù)協(xié)會(huì )的作用

The MaterialsTechnology Institute, headquartered in St. Louis,Mo., is an organization ofover 50 member companies, many of which use, fabricate, or manufacture titaniumor titanium equipment. MTI representatives include decision making personnelfrom many of the world's largest companies in the chemical and petrochemicalindustry. Each year MTI sponsors research projects that have a significant  benefit to  the  members' materials engineering efforts.    MTI member company representatives quicklysaw that an increase in the minimum specified tensile strength would lead toreductions in the cost of equipment they procure every year. In addition, MTI'smembership and reputation brought prestige to the project that was important ingetting cooperation from producers on a worldwide basis as well as gettingrecognition of the importance of the project by ASTM International, ASMEInternational, and other standards developing organizations.

材料技術(shù)協(xié)會(huì )，總部設在St. Louis,Mo.,是一個(gè)擁有50余人的企業(yè)機構，該部下屬的多數企業(yè)是從事應用、制作或制造鈦或鈦設備。每年，由MTI的主辦者研究與會(huì )員的材料工程具有重大利益的決策計劃。MTI的代表包括決策者在內，均來(lái)自世界從事化學(xué)、化工行業(yè)的大型企業(yè)。MTI會(huì )員公司的決策者迅速感受到使用比標準規定強度最小值更高的鈦設備將會(huì )大大降低他們每年生產(chǎn)設備的成本。另外，MTI之所以在國際ASTM、ASME和其他標準發(fā)展組織具有如此高的的全體成員威望，也正是由于他們的全體成員和制造商相互合作的重要設計方案帶來(lái)了全世界的公認。

總部設立于密蘇里州圣路易斯的材料技術(shù)協(xié)會(huì )，是一家擁有50多企業(yè)會(huì )員的組織，該組織下屬的多數企業(yè)都是從事應用、加工，或是鈦或鈦設備的生產(chǎn)商。MTI（材料技術(shù)協(xié)會(huì )）的代表包括決策者本身在內，均來(lái)自化工領(lǐng)域享有國際盛名的大型企業(yè)的決策人員。每年材料技術(shù)協(xié)會(huì )發(fā)起的項目對于該組織企業(yè)會(huì )員來(lái)說(shuō)都有著(zhù)重大的意義。MTI（材料技術(shù)協(xié)會(huì )）的會(huì )員公司的決策者迅速發(fā)現使標準規定的抗拉強度最小值提高將大大降低每年購置設備的成本。此外，MTI（材料技術(shù)協(xié)會(huì )）的企業(yè)會(huì )員和聲譽(yù)也給與之正在合作的來(lái)自世界各地合作商也帶來(lái)了聲望的同時(shí)，也得到來(lái)自美國ASTM國際、ASME國際和其他標準開(kāi)發(fā)組織對該項目重要性的認可。

 

The largerstudy, begun in 2002 and jointly sponsored by the Materials TechnologyInstitute, the International Titanium Association, and MC Consulting,³included data from over 30 producers worldwide, and over 8,000 data points.These data showed that over 99.5 percent of the Grade 2 unalloyed titanium in adatabase of 5,280 tests had a UTS significantly higher than the minimum 50 ksi(345 MPa) in the existing specifications, while covering the full range ofyield strength, as shown in Figure 1. The study also showed that the unalloyedtitanium Grades 1, 3, and 4 wrought-mill products also have similarly higherUTS values than indicated by current ASTM and ASME specifications.

2002年，由材料技術(shù)協(xié)會(huì )、國際鈦協(xié)會(huì )和MC咨詢(xún)處共同負責開(kāi)始深入研究，包括收集超過(guò)世界30家制造廠(chǎng)的8,000多組數據來(lái)源。5,280組統計數據表明：超過(guò)99.5%的Gr.2純鈦的UTS（抗拉強度）明顯高于現行標準最小指標50 ksi (345 MPa)。研究還表明，Gr.1、Gr.3和Gr.4純鈦的模鍛產(chǎn)品的UTS（抗拉強度）值同樣也比現行ASTM和ASME高。

 

   PROJECT OBJECTIVES

Grade 2titanium is widely used in the industrial corrosion sector and has become a defacto standard grade for most applications. This singular focus has allowed therelatively small titanium industry to offer a wide range of mill products andsizes, often from stock. Retaining thatfocus was a key objective of the project.

項目目標

Gr.2在工業(yè)上常用作抗腐蝕部件，是實(shí)際應用最廣泛的一種純鈦。對小企業(yè)而言，從制坯開(kāi)始，唯一的關(guān)注點(diǎn)在于制造的產(chǎn)品尺寸和加工量的控制。這一關(guān)注點(diǎn)對企業(yè)來(lái)說(shuō)至關(guān)重要。

鈦Gr.2在工業(yè)上常用作抗腐蝕部件，是實(shí)際應用最廣泛的一種鈦牌號。從庫存角度而言，這一關(guān)注點(diǎn)使得規模較小的鈦企業(yè)能提供更廣泛的軋機產(chǎn)品和規格。保留這一重點(diǎn)是該項目的一個(gè)重要目標。

 

   Objectives are summarized as follows:

D Take advantage of higher minimum UTS in ASME Code and relatedconstruction.

D Maintain the standardization on Grade 2 for industrial and generalapplications.

D Maintain the availability of full range of titanium products resultingfrom effective standard  ization on Grade2 for most industrial and general applications.

D Minimize any tendency for producers to change the current ingotchemistry formulations (i.e., increasing the oxygen or iron content to be morecertain of making the higher tensile strength).

D Determine if changes in other unalloyed grades, i.e., Grades 1, 3 and 4were warranted.

對此計劃概括介紹如下：

1、比ASME標準中UTS指標最小值更高的意義和相關(guān)介紹

2、保持標準規定的工業(yè)級Gr.2的必要性和應用概況

3、要保證鈦產(chǎn)品被廣泛利用，需憑借標準的有效版本規定的適用于大多數工業(yè)及常規應用的Gr.2

4、是當前材料生產(chǎn)者減小鑄錠化學(xué)成分目標值變化的要求（例如，增加Fe或O含量，勢必會(huì )提高抗拉強度）

5、確定是否調整其他純鈦牌號，如Gr.1、Gr.3、Gr.4的依據。

  PROPOSAL TO CHANGE MINIMUM UTS IN ASTM TITANIUM SPECIFICATIONS

    The project resulted in a proposal to ASTMCommittee to change the minimum UTS of not only Grade 2, but also of the other threeunalloyed titanium grades. This met with surprising resistance. However, theprocess to resolve the issues is a clear demonstration that the ASTM consensusprocess can produce a better result. Some of the concerns brought up bystakeholders are listed below.

調整ASTM標準中鈦材UTS（抗拉強度）最小指標的計劃

根據ASTM委員會(huì )BI0的提議方案，欲調整最小UTS的牌號不僅是Gr.2，還包括其他三種純鈦（Gr.1、Gr.3、Gr.4）。該提議肯定使人吃驚，并遭到反對。然而，解決這些問(wèn)題是有確定程序的，該方案只有取得ASTM的大多數人同意才會(huì )通過(guò)。各代表一些討論意見(jiàn)和關(guān)注點(diǎn)見(jiàn)下：

根據ASTM委員會(huì )BI0的提議，不僅要調整GR.2的最小UTS值，而且還包括其他三種純鈦（Gr.1、Gr.3、Gr.4）。該提議遇到了驚人的阻力。然而，解決這些問(wèn)題的過(guò)程清楚的表明與ASTM提議一致將會(huì )有一個(gè)更好的結果。部分利益相關(guān)者的擔憂(yōu)見(jiàn)下：

 

There was concern thatadditional restrictions in the specification requirements would lead tounnecessary product rejections even though the control of chemistry required tomeet the    proposed strength appeared tobe easily within the normal capability of the ingot producers.

盡管生產(chǎn)廠(chǎng)在正常生產(chǎn)條件下，鑄錠的化學(xué)成分控制很容易滿(mǎn)足提出的強度要求，但規范的附錄中還應涉及產(chǎn)品被拒收的可能性。

有人擔憂(yōu)，盡管生產(chǎn)廠(chǎng)在正常生產(chǎn)條件下，鑄錠的化學(xué)成分控制很容易滿(mǎn)足規定的強度要求，規格要求中的額外限制也會(huì )導致不必要的產(chǎn)品拒收。

 Some producers thought thatoverall consumption of titanium would decrease due to re  duced thickness requirements.

一些生產(chǎn)廠(chǎng)家則認為，由于范圍變窄，鈦的總消費量可能會(huì )減小。

There was a belief that achange in minimum UTS would cause the producers to reformulate their materialsto  meet the higher properties, giving upsome ductility and fabricability important to users of Grade 2 even though thedata showed that material above a specific oxygen level always met the 58 ksi(400 MPa) requirement and only material that had a low oxygen level (comparableto Grade 1) that was applied as Grade 2 fell below 58 ksi (400 MPa).

無(wú)庸置疑的是，由于UTS（抗拉強度）最小指標值調整，生產(chǎn)廠(chǎng)將會(huì )以改變原牌號各元素配比的目標值來(lái)滿(mǎn)足更高的性能要求，這樣會(huì )犧牲產(chǎn)品的延展性和對使用者來(lái)說(shuō)至關(guān)重要Gr.2的成型性能。盡管已有數據表明，原材料的氧含量水平在規范的偏上限時(shí)，強度總會(huì )滿(mǎn)足58 ksi (400 MPa)的要求，只有當Gr.2原材料的氧含量較低（與Gr.1比較）時(shí),強度才達不到58 ksi (400 MPa)。

ASTM Committee F04 on Medicaland Surgical Materials and Devices, which develops standards involving titaniumfor medical devices, known as the "F specifications,'' was concerned aboutany changes in basic specified properties because the regulatory process theyface to recognize such a change is long and costly. While the F specificationsspecify the affected properties independently, this was still a factor in notwanting to change the minimum

   property levels in the existing B (CommitteeBI0) grades. (The F specification grade requirements generally follow thegrades in the B specifications.)

由ASTM醫用和外科植入物材料和器械委員會(huì ) F04，開(kāi)發(fā)包含醫療器械用鈦材發(fā)展的標準就是眾所周知的“F （規范）”，該規范的最基本的性能指標調整之所以擔心這個(gè)修訂過(guò)程是漫長(cháng)的，代價(jià)也是昂貴的。然而，F規范有自己規定的相互獨立的性能，不愿調整現有B版純鈦級別中（委員會(huì )B10）性能最小值指標僅僅是其中的一種因素。（F規范的級別要求通常還是遵循B規范規定的級別。）

    The committee concluded that there was nocommercial incentive to increasing the UTS of Grade 1 since it is primarilyused for explosion cladding or plate heat exchanger applications where maximumductility is required and for chlorine anode substrates where higher electricalconductivity is also desirable. Committee B10 recognized that this need couldbe better served by reducing the minimum specified yield strength of Grade 1 toa level close to the lowest in the data base, which has the same effect on theratio of minimum UTS:YS of increasing the UTS of Grade 2. This was accompaniedby adding a supplemental requirement limiting the maximum yield strength to 40ksi (275MPa) instead of 45 ksi (310 MPa).The committee suggested reviewing thissituation in five years to see if a general shift in production would justifymaking the 40 ksi (275 MPa) upper limit mandatory.

委員會(huì )認為，提高Gr.1牌號的UTS是沒(méi)有商業(yè)動(dòng)機的，從起初只用于爆炸復合板或熱交換管板開(kāi)始，Gr.1就常用于對延展性要求高的場(chǎng)所，也常用作氯陽(yáng)極層，這是由于它具有良好的電導率。委員會(huì )B10公認，將規范中Gr.1的屈服強度的指標下限降低到接近統計數據的最低值是最好的，這與提高Gr.2的UTS對保持最小UTS:YS的比值不變是同樣的作用。同時(shí)，增加了一附加要求，即用Gr.1最大屈服強度40ksi (275MPa)代替了原來(lái)的45ksi (310MPa)。委員會(huì )查閱回顧了近5年來(lái)產(chǎn)品總的變化，可以看出，強行將YS（屈服強度）上限改為40 ksi (275 MPa)是合理的。

The committeealso concluded that there was little interest in changing the minimum UTS of Grade3 because it is less widely used for pressure equipment than Grade 2, eventhough the data showed it could be done. Also,about 30 percent of the material(in the database) that could be dual certified as Grade 2 and 3 at existing Grade3 minimum tensile strength would not meet the proposed higher UTS.

委員會(huì )還認為，不調整Gr.3的UTS最小值指標，因為雖然數據表明，它能應用于壓力容器上，但它還是沒(méi)有Gr.2牌號的應用廣泛。同時(shí)，（數據庫中）大約30%的材料既能被當作Gr.2，也能被用作Gr.3，可滿(mǎn)足當前Gr.3的最小抗拉強度要求，但不能達到提議中提到的更高的Gr.3的指標。

 

    Finally, the committee concluded that there was no reason to changeGrade 4 because it is not listed in the ASME Code.

最后，委員會(huì )得出結論，決定不調整Gr.4的指標，因為該牌號未列入ASME的牌號中。

    As a result, no changes were by the committee for Grade 3 or 4.

最終結果：委員會(huì )同意Gr.3、Gr.4牌號的指標不作調整。

     THE H GRADES

H牌號

    To be responsive to the user interest represented by the MTI study, andto address the concerns expressed, ASTM Subcommittee B10.01 on Titaniumdeveloped a consensus to add the 58 ksi (400 MPa) material as a separate grade,butlinked it to the standard Grade 2 by assigning it a readily associated Grade 2Hdesignation.

  通過(guò)MTI研究對使用方最感興趣的問(wèn)題作出了答復，他們發(fā)表言論，ASTM委員會(huì )的附屬委員會(huì )B10.01關(guān)于鈦發(fā)展已形成了統一認識，他們希望增加一種新的、獨立的強度為58ksi (400 MPa)的級別，將該級別命名為2H（Gr.2H），但很容易使人聯(lián)想到Gr.2。

         Grade 2H can always be dualcertified asGrade 2, and in nearly all cases, Grade 2 will meet the requirements of Grade2H. Since the standard numeric grades have been retained, it is expected thatingot producers will have minimal incentive to change their melt formulations.Retaining the standard numeric grades also addresses the medical applicationconcerns where the qualification of changes in material is costly. Thenomenclature "Grade 2H" is readily associated with "Grade 2,'minimizing the need to separately establish the H grades as a market standard.     These changes were incorporated in the2006a revision of the wrought titanium material specifications. H Gradecounterparts 7H, 16H, and 26H for the corrosion enhanced Grades 7 (Ti-0.12Pd),16 (Ti 0.06Pd), and 26 (Ti 0.1Ru) were also added to the specifications.

Gr.2H同時(shí)可被用做Gr.2，因為幾乎在所有情況下，Gr.2也都能符合Gr.2H的要求。標準保持這樣的級別，有利于刺激鑄錠生產(chǎn)商不改變原有成分的目標值，保持這種級別的編號形式，也可避免由于醫用成分與之有差異，使原料價(jià)格提高，從而限制鈦材在醫用的市場(chǎng)發(fā)展。“Gr.2H”這種命名法很容易使人聯(lián)想到“Gr.2”，在標準中將“H” 級別單獨列為一個(gè)牌號至少是一種市場(chǎng)需要。在2006 a鍛造鈦材料規范的修訂版中，已增加了這些變化。標準中增加的H級別的牌號還有7H, 16H和26H，它們分別是以Gr.7(Ti-0.12Pd), Gr.16 (Ti 0.06Pd)和Gr.26(Ti 0.1Ru)為基的用于提高耐蝕性的鈦合金。

ESTIMATED IMPACT OF THE HIGHER STRENGTH LEVELS

高強度水平的影響評估

 

It is difficultto estimate exactly how much this change will save industrial users each year.The 16 percent increase to 58 ksi (400 MPa) from 50 ksi (345 MPa) minimum tensilestrength and the corresponding increase of design-allowable stress in ASME isexpected to reduce equipment cost by an average of 10-16 percent, assuminglabor and material have equivalent cost. The market for affected equipment was estimatedto be of the order of $100 million. Thus, if the 58 ksi (400MPa) grades werefully implemented into pressure equipment,the annual savings could be as high as$16 million, year after year.

每年究竟有多少使用者會(huì )改用新的級別（牌號）很難準確評估。最小抗拉強度從50 ksi (345 MPa)增加16%后為58 ksi (400MPa)， ASME設計時(shí)的許用強度將相應增加，假使價(jià)格是由原材料和性能決定的，至少也將使設備的價(jià)格平均降低10~16%。鈦設備在市場(chǎng)上的訂購量總價(jià)約占10億美元。因而，如果壓力容器全部使用58 ksi (400MPa)級別的鈦材，以后的每一年相當于可節約1.6億美元。

  Finally, the higher strength addresses the currentshortage in titanium by reducing the amount of material required for a specificvessel. However, use of the H Grades is expected to result in more applicationswhere titanium is competitive，and over time a net increase in usage will result.//

無(wú)庸置疑，通過(guò)減少特種容器的的鈦材的使用量，將會(huì )緩解目前鈦材的緊缺局面。無(wú)論怎樣，在哪里鈦材有競爭，哪里H級別的鈦材用量將增長(cháng)，H級別用量不斷增長(cháng)也是必然趨勢。

最后，目前可通過(guò)減少特鐘容器所需的材料數量來(lái)解決當前高強度鈦的短缺。然而，只要有競爭的地方，H級的使用預計就能被更廣泛的應用，隨著(zhù)時(shí)間的推移它的凈使用量也勢必增加。

References

參考文獻

1、McMaster, James A., "Is itTime to  Modernize the ASTMSpecifications for Unalloyed Titanium," presented at the "Titanium,Its Role, Its Growth and Its Applications in the  CPI" session, 49th CPI Exposition,  Javits Convention Center, New York,  New York, October 23~25, 2001

2、McMaster, James A.,"Rationalization of Unalloyed Titanium Material Specifications to CurrentProduction Capabilities Offers Opportunities for  the Titanium Industry," presentedat  Corrosion 2003, San Diego, Califonia,March 16 to 20, 2003

3、Final Project Report, Phase1,  ASTM Strength Revision Project  151-02, October 15, 2003, Materials  Technology Institute of the Chemicai ProcessIndustries, Inc., 1215  Fern RidgeParkway, Suite 116, St.

 Louis, Missouri 63141-4405

 

Benefits of new titanium specs

 

1、Opportunities exist for specification upgradesbased on modern material properties.

2、Producers as well as users canbenefit by tightening specifications to reflect improved productioncapabilities.

3、Change should be considered interms of both production risks and marketing benefits.

4、The H Grades will make titanium morecompetitive compared to other materials, and to some extent will help addressthe current shortage of titanium.

5、User groups can fulfill the role of developingor optimizing requirements for materials that has traditionally been filled bythe producer of the materials.

6、Revisiting existing old data with modernanalytical methods can produce useful/beneficial changes.

7、Tighter limits on properties in productspecifications may result in significantly higher design allowable stresses incodes and standards that use the statistical methods to determine theseallowable stresses.

8、Modernization of specifications to reflect theimprovements in product quality and consistency is one way ASTM committees cancontribute to making investments in improved material production worthwhile.

 

新規范的優(yōu)點(diǎn)

1、以現有材料性能為基礎，提高了本規范水平。

2、將高指標要求的產(chǎn)品納入標準后，生產(chǎn)者和使用者都會(huì )受益。

3、標準的變化考慮了產(chǎn)品風(fēng)險和市場(chǎng)效益。

4、與其他材料比較，H級別將使鈦材更具有競爭力，更深一層說(shuō)，會(huì )緩解目前的鈦材短缺的局面。

5、有助于使用者實(shí)現發(fā)展或優(yōu)化所需材料的作用，也有利于生產(chǎn)者按傳統方式供應材料。

6、用現有的分析方法回顧積累的數據會(huì )發(fā)現這是一種有益的變化。

7、在產(chǎn)品規范中規定的性能極限值增高對按該級別（牌號）設計許用壓力意義重大，因為設計者是按標準規定的極限用統計方法來(lái)決定許用壓力的。

8、現代規范表現出的產(chǎn)品質(zhì)量和質(zhì)量一致性提高是ASTM委員會(huì )為提高材料生產(chǎn)質(zhì)量所做投資的必然回報。