I am looking to purchase a Vickers (HV10) hardness tester for use in weld testing and welding procedure qualification. Unfortunately, I have little experience with this equipment, and I need to find out who makes good equipment, and perhaps just as importantly, who to stay away from. I'm not sure this is the right place to post such a question as this, but I am having difficulty finding information other than just links to various manufacturers' websites. Any information would be greatly appreciated, whether it is about specific equipment or links to other forums or sites that would contain this sort of thing.
You mention that you want to perform "weld testing". Does this mean that you want to perform hardness tests on production welds in the field. If this is the case, then vickers is not a very practical test. Rather, you should try to get one of the field testers that are based on the height that a steel ball bounces off the surface. A good brand name here is "Equitip". (I think that is the correct spelling.) These pieces of equipment are easy to use, relatively cheap and robust.
Once the reading is taken in the machine's own units, you can translate them via tables to any other units such as vickers, brinell etc. Obviously these readings are not "stricktly speaking" a vickers test, but in most circles the readings will be accepted when reported in Hv.
Obviously for qualifying procedures, you can section the weld and polish it. Then a vickers tester is good. - Try (who else) VICKERS.
Hope this helps
Regards
Niekie Jooste
By sdray
Date 04-22-2002 12:58
I suppose I should have been a little clearer. I do not intend to use a Vickers test on production welds; only on specimens cut from welds and polished and etched. I am aware that the Vickers test is not a good field test, but I do not intend to use it that way. I have been using a Rockwell hardness tester to perform hardness tests on macro specimens, but our customers want to see a Vickers test done. I could easily send this out to a third party lab, but past bad experiences with local labs, and even some not-so-local labs makes me want to do as much testing myself as possible. I can't afford to have it screwed up. We already do all of our own procedure qualification testing, including tensiles, bends, Rockwell hardness, and Charpy impacts, for this very reason.
For some reason I've not understood, Brinell hardness measurements, which were very popular in the U.S. until 8 - 10 years ago, have been gradually replaced by Vickers', which are now in wide use. Anyway, this is none of my business and I'm supposed to answer questions and not to make silly comments.
I believe it's unethical to recommend in this site a specific brand of equipment. Someone could think that we are using this site in favor of our commercial interests.
What I recommend you to do is to get hold of a respectful technical magazine such as Welding Journal, Mechanical Engineering or American Machinist. There are plenty of advertisements there regarding hardness testers. Which one to buy? Not necessarily the cheapest. Ask them a quotation and, MOST IMPORTANT, a list of references, i.e., users of the equipment similar to that you want to buy.
Check carefully ALL OF THE REFERENCES, prefererably by phone, so you can speak personally with them. Ask them whether they are satisfied with the equipment. DON'T THINK that just because the references have been included into the list they're happy with the equipment.
I've personally used this procedure a lot of times, and I'm sure it'll give you enough information to make a good decision.
Good luck
Giovanni S. Crisi
Sao Paulo - Brazil
We have seen several failures in sour gas service where the weld and HAZ passed the Brinell hardness requirements.
It appears that the size of the ball gives a good average hardness, but will not discover a small hard zone.
One case in particular was a dissimilar weld - carbon to stainless. A standard microhardness scan was done (a certain number of indentations at a prescribed interval). After the failure, our technician polished the failure, put it under the microscope and found a very, very thin hardness zone that extended from the root to cap, parralelling the fusion line. It could be found easily with Vickers 500 gm load, but Rc, BHN, and possibly even Hv10 would have missed it.
The Krautkramer MIC 10 is a portable hardness tester that will give you Vickers, Rockwall, and Brinell digital output readings. While it is very expensive, espically if you get the statistical and data recorder package, it is also great on small parts and thicknesses. Many of the units use a rebound method and if you do not have enough mass in the test part your readings will have an error. The Krautkramer MIC 10 is fairly easy to use but will not take abuse. It uses a diamond indentor coupled to a piezoelectric crystal. I wanted to obtain one for the company I work at but the price tag was too high. There are bench types of equipment that while not portable may suffice for your needs.
