confidence about durability of tempered hardboard

I’m a painter, not a conservator, so I don’t have access to scientific testing of these substrates (of which I don’t think there is much, anyhow).  Still, I’ll contribute a few thoughts on the subject.
1. will this engineerd wood material degrade with time, like cracking, delaminate and lately returning back to wood fibers? 
Fiberboards (of which hardboard is one type) are made from a slurry of wood fibers pressed together under tremendous heat and pressure, held together by the natural lignin in the wood, sometimes with the addition of glues or resins for additional strength (as in a tempered board).  
I don’t think of fiberboards as cracking or delaminating, which presupposes a layering or laminate (not a fibrous) composition.  Fiberboards have been known to chip or split, particularly at the corners, when exposed to hard knocks or blows, or excessive moisture.  I’ve never heard of a fiberboard returning back to wood fibers as the natural lignin and glues/resins that hold these boards together are quite strong. 
2. will the nature lignin degrade and migrate and increase acid leverl, that will damage painting layer?
All wood products contain acidic components, such as tannic acid – it’s just an inherent quality of any wood-based support (solid, plywood, fiberboards).  There are ways to protect against this; for example, by applying an under layer of gesso composed of alkaline materials (calcium carbonate/chalk or calcium sulphate/gypsum).  Many old master paintings on solid wood panels have survived well despite the acidic nature of wood, due to a sound building of the layers (i.e. not painting directly on wood but on top of gesso). 
3. if this engineered wood substatre become degrade, but art work is patining directly on top, does this mean the art work is gone?
This is a complicated question to answer – it depends on how degraded the substrate is, if there’s a gesso and/or linen layer under the painting that isolates it from the substrate, how much and how good are remedial conservation efforts, etc.  Obviously it’s not good to have a substrate degrade, but many a painting has been rescued from a degraded substrate given good circumstances and treatment.
4. so does a more durbale/archival option is always using linen glued on rigid panel, that will last much longer than tempered hardboard? 
I’m not sure what you mean by rigid panel: solid wood, plywood, aluminum panel?  Each of these options has strengths and weaknesses; for example, solid wood is more prone to splitting than plywood, but plywood is more prone to delaminating (although I tend to think plywood is overall more durable… unless the solid wood is an old growth [with wide rings] quarter sawn, hardwood that’s been well aged and stored in good conditions; than solid wood can be more durable).   Aluminum is very durable, but also can have decreased adherence between the various layers of a painting because it lacks porosity (i.e. a gesso layer may not adhere as well to metal as it does to a wood-based substrate).  
In other words, there are so many variables within the disparate materials of which a painting is composed that it’s hard to give simple, definitive answers.  It may seem I am being unnecessarily difficult; that I’m trying to complicate the topic, but in fact slight differences in materials and methods can make a tremendous difference in the durability of a painting (i.e. as in the “solid wood panel” example cited above; there are tremendously consequential differences between different types of solid wood panels).  
If I were to rank in order of durability the three wood-based options (solid wood, plywood, fiberboard) – none of which are likely “artist-grade”; pretty much all are intended for the building trades, excluding a few products by small-time, specialty craftsmen – I would, personally, cite plywood as the most durable, as long as it’s a high-quality plywood, of sufficient plys, coated with cloth (without cloth, the wood grain pattern of plywood veneer can telegraph through a painting over time and be disastrous).  
However I don’t consider fiberboard dramatically worse than plywood if the fiberboard is high-quality, tempered, 1/2″ thick, also coated with cloth (even tho’ fiberboard doesn’t have a grain pattern, cloth nonetheless helps stabilize a panel).  I think, given those ideal conditions, a case can be made for fiberboard as a reasonably durable support alongside plywood.  
Hope that helps, Koo Schadler
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​so when you say coated with a cloth, do you mean gluing a linen canvas on wood panel for a more durable option, as linen canvas has historical proven? 
Yes, linen has very strong fibers, so if I had to choose a fabric linen would be my first choice.  However you could also use a cotton-based fabric (for example, cotton duck is quite strong).  Or, if you are working with synthetic glues, you could choose a synthetic fabric; for example, “Dyneema” is considered the strongest fabric with a strength 15 times greater than steel.  I don’t have actual experience with synthetic materials because I paint on animal glue-based gesso, and animal glues don’t adhere well to synthetic materials; it’s just to say synthetic fabrics are another possibility, depending on your materials and methods.
may i ask what is the substrate you are painting on? do you use plywood glued w/ linen canvas? if so, does the glue is acrylic medium? and do you think the natural oil contained in linen fabric will prevent good adhesion of acrylic based primer?
The majority of my paintings are small (i.e. 8 x 10″ or less) and small panels have less demands placed on them (they move less, are less subject to getting knocked about, etc.).  I use HDF (high density fiberboard) or MDF (medium density fiberboard), 3/8″ thick panels.  Sometimes I coat them with linen, sometimes I do not (depends on panel size – a bit of overkill to coat a 3″ square painting with fabric – and studio time) .  For larger paintings I use 1/2″, baltic birch plywood coated with linen.  I’m meticulous in my panel preparations (for example, rough up the surfaces to encourage good adhesion; apply a layer of glue over all surfaces; use a high quality, strong [450 bloom strength] glue, ​etc.).   
Because I use animal glue-based gesso, I don’t use synthetic glues (to which animal glue doesn’t adhere well); however synthetic glues are very good, and I recommend them over animal glue if one is using a synthetic polymer-based gesso.  
While flax seed does produce a rich oil, the seeds are different from the plant fibers from which linen is made, so I wouldn’t worry about the oil content of linen, which is minimal if at all present (i.e. linen clothing do not give off oils onto the skin).  
i also curious when you rank the plywood to be best, does that based on its dimentional stability? how about if we have any confidence on its glue used, will that degrade much faster over time, as the glue longevity is never an intend for manufacturing, and now the glue formular had changed to meet CARB. 
One of the biggest problems with wood as a substrate is it’s water loving (hygroscopic) nature, which causes it to expand and contract.  Of the various wood-based substrates – all of which move – I think a high quality plywood, with many plys (minimum 5, up to 7 or more) offers the most stability.  
But you are right – the glues, while very strong, do age and degrade (one reason to look for a high quality plywood); however a fine art painting, ideally, is not subject to the extremes of temperature, weather and use that plywood in a home can be exposed to, so that is a help to the glues.  
There’s no getting around that most wood products are made for the building trades, not fine art – and that there are not a lot of resources for fine artist grade, wood-based substrates.  If you can find and pay for a good craftsman who searches out old growth, quarter sawn wood (for example, antique mahogany furniture – it may sound extreme, but I knew a painter, Ross Merril, head of conservation at the US National Gallery at one time, who did just that) and then properly prepare it….well, that would be great! But of course this is not a realistic option for most painters.  
There are some art companies (i.e. Ampersand) selling fiberboard panels they make themselves, specifically for artist use, which Ampersand claims are superior to lumberyard fiberboard – you could give that a try, but they are too thin for my preference.  Or, you could say no to lumberyard wood all together and switch to artist grade linen canvas stretched onto artist-grade frames – but the evidence is pretty strong that a rigid support is superior to a canvas painting, even when that rigi support is a lumberyard sheet of plywood!  So in the end there are no easy solutions to making a perfectly durable painting.  I would say if you can work on a 7-9 ply, baltic birch, 1/2″ or thicker (tho’ for my size paintings, over 1/2″ thick is likely overkill) plywood coated with fine linen – that’s pretty good.  Or a well prepared fiberboard.    Of aluminum, if you are working on a synthetic polymer  gesso.  Good as each of those can potentially be, they still all have flaws as well – there’s no perfect, reasonable solution (at least, not that I know of).

Koo  ​

for linen canvas, i heard it need to rinse in warm water few times before use, does that true? 
Wash any fabric in warm water with a bit of soap to get it clean (I do it this is a washing machine).  Do NOT dry electrically – let the fabric dry on the line, naturally – otherwise you risk shrinking and tightening the fibers.
also, if we glue fabric to wood panel, say tempered hard board, MDF, plywood, etc, we are assuming fabric canvas will last much longer than those wood panel? but if the glue is permenant and the panel degrade, doesnt the fabric can also get damaged along with? 
There is no absolute permanence to any of these materials.  So no, I’m not assuming the fabric will necessarily last longer.   I am assuming that if all the materials are good quality and your preparations/methods are good, and the artwork is kept in reasonable conditions (no temperature or humidity extremes), the painting as a whole will last a reasonable amount of time (potentially centuries).  Of course a single adverse circumstance (bad environmental conditions; bad treatment while the work is in transit; etc.) can change all this; this is the perilous fate of all artwork!
Or if there is data to show engineed wood panel can last as long as fabric?   I don’t have data on any of this, I’m a painter, not a conservator (tho’ even conservators may not have comprehensive data on the materials you’re interested in).   However between my personal experience and research, and my conservations with many conservators, I would say that wood panels and fabric can last a long time if the materials are good quality and your preparations are good and the artwork doesn’t experience traumatic circumstances.  This is the best you can hope for – nothing made of matter lasts forever.
and are you using acrylic medium to glue the canvas to wood? i found due to the wave pattern of fabric, the acrylic is too thin to bond well, and it dries too quickly if spread it all over the panel first, so that no enough time to adhere large canvas i found. maybe need use a lot of acrylic medium to fill into the wave of fabric and gluing from side to side?   As mentioned, I work with animal glues when I attach fabric since I apply an animal glue gesso.  
If you are having problems with glue on fabric drying out, try spritzing the canvas with water as you move over the surface applying glue, to keep things moist.  And yes, you will need to use a lot of glue to fully coat the fabric.  
You could also try putting a preliminary coating of glue over the entire fabric, smoothly and thin, and letting that dry.  Then when you’re ready to actually attach the fabric to a panel, apply a second coat, a lot of it, to fully coat the fabric – it won’t sink in as much due to the first, dried coating.  You may still need to lightly spritz the surface with water as you go, to keep the glue moist.  It may take practice, doing this a few times, to develop a method that allows you to get very good coverage – you want every inch of the fabric attached with a good amount of glue – nothing unattached.
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Hello Again,
I attach linen to plywood panels to prevent the plywood’s grain pattern from telegraphing through the gesso up into the paint layers.  I’ve seen this happen to paintings, both recent ones and paintings that are several decades old, and the grain pattern eventually causes cracks in the paint layers.  
I do not attach linen to plywood in order to paint atop the weave; in fact, I fill in the weave with many layers of gesso that I then sand smooth, to work on a perfectly consistent surface – as is the preference for most egg tempera painters, including myself. I don’t generally attach linen to fiberboard panels (which don’t have a grain pattern), but once in a while I do – for an expensive commission, for example – as it just imparts a bit more stability to the multi-layered construction that is a painting.  I appreciate that greater degree of stability.  I don’t think in terms of the fabric layer being more or less durable than a wood panel – wood is an imperfect substrate, but nonetheless a pretty good one (the only more durable option being an aluminum panel, although that too has flaws).  My paintings are well enough made that I expect them to last for at least a generation or two (or longer), presuming no surprising traumatic event.   I don’t imagine conservators working on my paintings; very few paintings have sufficient value to end up in a conservator’s hands.  I just try to make the best painting I know how, send it out into the world, and then leave its future to the fates.​